WO2001058426A1 - Sustained release composition comprising insuline like growth factor - Google Patents

Sustained release composition comprising insuline like growth factor Download PDF

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Publication number
WO2001058426A1
WO2001058426A1 PCT/CH2000/000074 CH0000074W WO0158426A1 WO 2001058426 A1 WO2001058426 A1 WO 2001058426A1 CH 0000074 W CH0000074 W CH 0000074W WO 0158426 A1 WO0158426 A1 WO 0158426A1
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igf
release
pharmaceutical composition
microspheres
composition according
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PCT/CH2000/000074
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French (fr)
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Lorenz Meinel
Bruno Grander
Oscar E. Illi
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White Spot Ag
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Priority to AU22757/00A priority Critical patent/AU2275700A/en
Priority to PCT/CH2000/000074 priority patent/WO2001058426A1/en
Publication of WO2001058426A1 publication Critical patent/WO2001058426A1/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/14—Particulate form, e.g. powders, Processes for size reducing of pure drugs or the resulting products, Pure drug nanoparticles
    • A61K9/16—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction
    • A61K9/1605—Excipients; Inactive ingredients
    • A61K9/1629—Organic macromolecular compounds
    • A61K9/1641—Organic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polyethylene glycol, poloxamers
    • A61K9/1647—Polyesters, e.g. poly(lactide-co-glycolide)
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K38/00—Medicinal preparations containing peptides
    • A61K38/16—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • A61K38/17—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
    • A61K38/22—Hormones
    • A61K38/30—Insulin-like growth factors, i.e. somatomedins, e.g. IGF-1, IGF-2
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/14—Particulate form, e.g. powders, Processes for size reducing of pure drugs or the resulting products, Pure drug nanoparticles
    • A61K9/16—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction
    • A61K9/1605—Excipients; Inactive ingredients
    • A61K9/1629—Organic macromolecular compounds
    • A61K9/1658—Proteins, e.g. albumin, gelatin
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/06—Organic compounds, e.g. natural or synthetic hydrocarbons, polyolefins, mineral oil, petrolatum or ozokerite
    • A61K47/08—Organic compounds, e.g. natural or synthetic hydrocarbons, polyolefins, mineral oil, petrolatum or ozokerite containing oxygen, e.g. ethers, acetals, ketones, quinones, aldehydes, peroxides
    • A61K47/10—Alcohols; Phenols; Salts thereof, e.g. glycerol; Polyethylene glycols [PEG]; Poloxamers; PEG/POE alkyl ethers
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/30—Macromolecular organic or inorganic compounds, e.g. inorganic polyphosphates
    • A61K47/42—Proteins; Polypeptides; Degradation products thereof; Derivatives thereof, e.g. albumin, gelatin or zein

Definitions

  • This invention relates to pharmaceutical compositions designe ⁇ for sustained release of an effective amount of a stabilize ⁇ polypeptide and a process for preparing tne composition.
  • IGF-I msulm-like growth factor 1
  • hIGF-I Human Insulm-like growth factor I
  • IGF-I In the context of joint biology, IGF-I seems to play an important local role in bone proliferation and bone healing after injury. Cell proliferation and matrix synthesis by chondrocytes and osteoblasts is promoted by IGF-I. Both cell types are largely responsible for the formation of the fracture callus. Interestingly, administration of IGF-I increases bone turnover in patients with low mineral density. Furthermore, tnere is evidence that IGF-I accelerates the normal healing of bone defects, even those which normally show heavily impaired healing. A typical role of IGF-I is to mediate the effect of growth hormone (GH) on skeletal growth. Although IGF-I is not a potent mitogen m bones, there are nigh affinity receptors for IGF-I on osteoblasts, and IGF-I can stimulate precsteoblast replication and provoke resting cells to proceed througn their cell cycles
  • the EP-A-0 ' 980 ' 273 discloses an implant made of a polmenc biodegradable base material for use in reconstructive osteosynthes s containing growth factors like IGF-I.
  • the active ingredient has been worked into the implant in a way to aid bone growth in the area of the fracture. It is suggested to encapsulate the growth factors in a biodegradable polylactide material by means of "in water drying" of W/O/W emulsions.
  • a huge number of biodegradable polymers have been described for controlled parenteral and mucosal drug delivery (e.g. J. Heller, Polymers for controlled parenteral delivery of peptides and proteins, Adv. Drug Delivery Rev. 10, 163-204, 1993) .
  • microcapsules or microspheres The three most common methods for the production of microcapsules or microspheres are a) solvent evaporation/extraction, b) coacervation (or organic phase separation) and c) spray drying. Common to the three major methods is the dispersion of the aqueous protein soultion in an organic polymer solution, non- miscible with the organic phase. For ⁇ ifferent proteins and also for antigens numerous solvents and emulsification methods have been described. However, the release dynamics of pharmaceutically active proteins enclosed m microcapsu es or microspneres are often unpredictable and uncontrollable (T.G. Park et al., Journal of Controlled Release, 211-222, 1995).
  • microencapsulation of protein drugs is generally critical for protein stability.
  • DCM dichlormethane
  • cetones cetones
  • alcohols to aqueous/ organic interfaces and to shear and cavitational forces necessary to form the W/O/W- emulsions may be rather detrimental to protein structure ana activity.
  • These stress conditions may sometime lead to protein aggregation, as it has been described for growth hormone, or for insulin. It stands to reason that these effects are more abundant when the interface growths.
  • IGF insuline like growth factor
  • a method of forming a pnarmaceutical composition comprises mixing an aqueous stock solution containing IGF-I, a buffer solution, a polymer nydrolysis modifying agent and a protein stabilizing agent; emulgating said mixture in an organic solvent containing saic encapsulating polymer oy ultrasonication; a ⁇ ding said W/O- dispersion to an aqueous PVA-solution to form a W/O/W- dispersion by mecnanical stirring; extracting the organic solvent; ana collecting, wasning and drying of the microcapsules and/or microspheres from this solution.
  • a pharmaceutical composition in accordance with another aspect of the invention, comprises a naturally occurring msuline like growth factor (IGF), a synthetically prepared material of the same type or synthetically prepared analogues of naturally occurring IGF microencapsulated in tne presence of a protein staoilizing agent.
  • IGF msuline like growth factor
  • a parenterally admimstrable therapeutic composition can be formed by encapsulating the protein with a lactide/glycolide molar ratio of the copolymer, its molecular weight, the capsule diameter, the capsule surface and the polymer stabilizing agent, being such that the composition exhibits sustained release of an effective amount of the bioactive polypeptide within 3 to 4 weeks showing a first peak after 12 hours to two days, or after about 6 to 10 days or after about 12 to 15 or after about 15 to 21 days (i.e. monophasic release pattern) .
  • a parenterally admimstrable therapeutic composition can oe formed by microencapsulatmg the protein with a lactide/glycolide molar ratio of the copolymer, its molecular weight, the capsule diameter, the capsule surface and the polymer stabilizing agent, being such that the composition exhibits sustained release of an effective amount of the bioactive polypepti ⁇ e over a pe ⁇ o ⁇ of at least 3 to 4 weeks showing an initial burst and a second peak after aoout 6 to 10 days (i.e. bipnasic release pattern) .
  • a parenterally a ⁇ ministrable therapeutic composition can be formed by microencapsulatmg the protein witn a lact ⁇ e/g_yco ⁇ ide molar ratio of tne copolymer, ts molecular weight, tne capsule diameter, tne capsule surface ana tne polymer staoiiizmg agent, ⁇ eing sucn tnat tne composition exhibits sustained release of an effective amount of tne bioactive polypeptide over a period of at least 3 to 4 weeics showing an initial burst and a second peak after about 6 to 10 days ana a third peak after about 15 to 17 days (i.e. t ⁇ pnasic release pattern) .
  • a parenterally admimstrable therapeutic composition can be formed by mixing at least two different types of the above mentione ⁇ microcapsules .
  • a parenterally admimstrable therapeutic composition can be formed by mixing at least two different types of the above mentione ⁇ microcapsules .
  • three different types of "simple" monophasic microcapsules exhibiting peaks after 12 hours to two days, 6 to 10 days and 15 to 21 days a very complex release pattern can be achieved.
  • a parenterally admimstrable therapeutic composition can be formed with up to 85% entrapment efficiency. Meaning that less than 15 % of the protein present in the initial stock solution is not encapsulated m a bioactive releasable form.
  • IGF-I controlle ⁇ release composition useful in promoting restoration of bone defects by controlling ana maintaining IGF-I release in si tu over up to 10 weeks, preferably 3 to 4 weeks is a further objective of tnis invention .
  • It s another objective of the present invention to provi ⁇ e a pharmaceutical composition ⁇ esigned for sustained release of an effective amount of a proteinaceous drug over an exten ⁇ ed pe ⁇ o ⁇ of time prepare ⁇ m microcapsule or microspnere fcr wnere tne ⁇ rug is released pronounce ⁇ tri- or multiphasic release patterns.
  • Fig.l IGF-I degradation upon ultrasonic homogemzation of an aqueous IGF-I solution in dichlormethane phase (W/O) ;
  • Fig.2 influence of various excipients on IGF-I stability upon ultraso cation (25Watt, 15 seconds).
  • the amounts of additives are given under Materials ana Methods.
  • Fig.3 entrapment efficiency of intact IGF-I m PLGA 50:50 microspheres . Co-encapsulation of various additives ha ⁇ a strong stabilizing effect. The percentages of additives reppresent amount of soli ⁇ exc pient material with respect to polymer mass . The initial W/O- ⁇ ispersion was ootamed by ultrasomcation at 25W for 15 s;
  • F g.4 in vi tro release profiles of IGF-I from PLGA 50:50 microspheres.
  • the curves represent microspneres preparations containing various cc- encapsulate ⁇ additives: Percentages of additives represent amount of soli ⁇ experiment material with respect to polymer mass; and
  • Fig.5 the in vi tro release profiles of IGF-I from figure 4 in a single graph.
  • End-group uncapped Poly (lactide-co-glycolide) 50:50 (PLGA 50:50) with a M consult of approx. 14 kDa was purchased from Boeh ⁇ nger Ingelheim ( Ingelheim-Germany, Resomer ® RG502H) .
  • Bovine serum albumin (BSA) was from Fluka, CH-Buchs, and human serum albumin (HSA) from the Swiss Red Cross, CH-Bern.
  • Manmtol, ⁇ -cyclodextrm and trehalose were from Sigma-Aldrich, CH-Buchs, and msulm-like growth factor was kindly supplied by Chiron, Emeryville CA.
  • Dichlormethane (DCM) and acetomtrile were purchased from Scharlau, CH-Tagertwil . Unless specified otherwise, all other substances used were of pharmaceutical or analytical gra ⁇ e and purchased from Fluka, CH-Buchs. For radioimmunoassay (RIA) testing, an anti-IGF-I antibody previously produced in rabbits was used. The anti-rabbit ⁇ - globulm (goat) from Novabiochem (CH-Laeufelfmgen) .
  • IGF-I loaded microspheres A W/O/W solvent extraction-evaporation metno ⁇ was used to prepare IGF-I loaded microspheres.
  • 0.15 ml of internal aqueous phase consisting of 13.5 ⁇ g of IGF-I in 10 mM so ⁇ ium succmate plus 140 mM sodium chlo ⁇ e of pH 6.0 were emulsified m 2 ml of a solution of 50 mg of PLGA 50:50 n DCM.
  • the internal W- pnase contained additional excip ents: 2.5 mg BSA, 2 mg solid material of Physiogel ® (80 mg/ml of succmulated gelatin, Braun Medical (B.Braun Medical AG, CH-6020 Emmenbrucke) , 2.5 mg BSA -r 2 mg of solid material of Physiogel ® , and 2.5 mg BSA + 12.5 mg PEG 400) Emuisification was achieved by ultrasomcation (50 W, 15 s).
  • the obtained W/O-dispersion was poured into 30 ml of a 5 % (w/v) external aqueous solution of poly (vinyl alcohol) (PVA) to form a W/O/W-dispersion by mechanical stirring at 500 rpm for 1 mm.
  • PVA poly (vinyl alcohol)
  • This W/O/W-dispersion was subsequently poured into 400 ml of de-iomzed water and stirred for 25 mm with a magnetic stirrer to extract the organic solvent. Afterwards, the particles were collected on a regenerated cellulose (RC) membrane filter of 1 ⁇ m pore size and washed 4 times with 100 ml of de-ionized water.
  • RC regenerated cellulose
  • the particles were finally dried under reduced pressure (approx. 100 mbar) at room temperature for 7 h.
  • aqueous IGF-I solution 75 ⁇ g/ml IGF-I m 10 mM succmate buffer, pH 6) was emulsified in 1 ml DCM.
  • the excipients 25% PEG, 3% BSA, 3% trehalose, 3% Manmtol, 5% ⁇ - cyclodextrm, 25% Physiogel ® or combinations thereof (see Fig.l) were added to the aqueous phase.
  • the W/O-emulsification was done in a PTFE tube using ultrasomcation (50 W, 15 s) . Afterwards, the phases were separated by centrifugation, ana the concentration of IGF-I in the upper phase was determined oy HPLC.
  • IGF-I release from 20-40 mg microspheres was conducted in 4 ml PBS of pH 7.4 in rotating borosilicate vials at 37°C and assayed by ra ⁇ ioimmunoassay .
  • certain amounts of the medium was replaced by fresn buffer and analyzed by RIA, after separation of the particles and the supernatant by centrifugation at 3500 rpm for 10 mm.
  • the pH was monitored and held constant at a pH of 7.4. Release experiments were performed in triplicate.
  • High-performance liquid chromatography was used to assay IGF-I.
  • the system consisted of a A6000 computer interface (Merck,), a 6200A pump, L4250 UV and F 1050 fluorimet ⁇ c detectors, a A4000 automjector, and a sample cooler (all from Merck, CH-Zuerich) . Separation was performed on a Zorbax ® 300SB CN-column (150*4.6 mm) at ambient temperature (30°C), using an isocratic system at a flow rate of 0.8mL/mm. The eluent was composed of 26% acetomtrile, 74% HPLC grade water, and 0.2 ml of t ⁇ fluoacetic acid per liter. After eacn run, the column was washed with 80% acetomtrile and 20% HPLC grade water. IGF-I was detected at 214 nm and quantified by measuring the peak area .
  • the radioim unoassay for IGF-I was carried out as ⁇ escribe ⁇ previously. Pure IGF-I served as standar ⁇ .
  • microparticles were re ⁇ ispersed in 2-3 ml distilled water containing 0.1% T een' 20 for severa_ minutes m an ultrasonic oath Branson) .
  • the size was determined by ⁇ aser diffractometry using a Malverr Mastersizer X (Germany) .
  • FCA Fat cell assay
  • IGF-I insulin antiserum
  • IGF-I upon ultrasomcation (US) is shown in Figure 1.
  • IGF-1 cone. 75 ⁇ g/ml
  • m 1 ml DCM/acetone (3:1, v/v) were sonicated to form the primary W/O emulsion.
  • Ultrasomcation with 50 W for 15 s caused severe protein degradation, with only 36% of IGF-I remaining intact.
  • ultrasomcation with 25 W for 15 s 48% of IGF-I remained intact.
  • Milder US-conditions of 25 W for 5 s or 10 W for 10 s or the use of a vortex mixer were insufficient for emulsification .
  • IGF-I degraded substantially under the homogemzation conditions necessary to form the primary W/O emulsion.
  • excipients such as sugars, polyalcohois, cyclodextrmes or other proteins
  • IGF-I was microencapsulated by the solvent evaporation technique at drug loading levels in the range of 0.2 to 0.7 % (w/w) . Batch sizes of 30 to 150 mg polymer yielded 72 to 86 % of dried microspheres. Particle size was 61 ⁇ 11 ⁇ m. Accurate determination of the protein content in microspheres was rather critical, as already pointed out by others. IGF-I was extracted from the microspheres by dissolving them in DCM. The in DCM insoluble IGF-I was then separated using centrifugation . Separation by filter membranes gave unreliable results due to strong adsorption of IGF-I to the filter materials. The encapsulation efficiency, defined as the ratio of actual over theoretical IGF-I content, was between 23 and 81%, depending on the co-encapsulation of various excipients (Fig. 3) .
  • IGF-I insulin growth factor-I
  • stabilizers If IGF-I was not protected by co-encapsulated additives or stabilizers, it degrades as indicated by HPLC. Without stabilizers, the apparent encapsulation efficiency amounted to only 23% (column 1). By contrast, approx. 80% entrapment efficiency was measured in the microspheres containing either 5% of BSA or 4% of Physiogel ® (Column 2 and 3 respectively) ; percentages of additives represent amount of solid excipient material with respect to polymer mass.
  • Figure 4 shows the m vi tro release profile of IGF-I from PLGA microspheres pro ⁇ uced with different excipients.
  • the initial burst of tne formulation witn BSA ana Physiogel ® is roughly 40% while all other formulations show smaller bursts.
  • All formulations show a more or less attenuated typical t ⁇ pnasic release pattern.
  • the formulation with Physiogel ® alone enters the third phase at day two to three the formulation witn BSA and Physiogel ® and 2% NaCI in the outer phase enters it at day 5.
  • the other formulations are more retarded especially the formulations with BSA and Physiogel ® and 5% NaCI and the one with BSA alone.
  • IGF- I released during the third phase was approx. 30-50%. Only the combination of BSA and Physiogel ® m the microspheres led to a poor release of IGF-I in this phase of approx. 10 %.
  • the sheerness of the third phase was very similar for formulations made with BSA and Physiogel ® and 5% NaCI in the outer phase and the one just made with BSA and exhibited a continuous release lasting over 5 days.
  • IGF-I is sonicated with relatively force conditions it shows heavy degradation of approximately 60 to 70 %.
  • a sufficient first W/O emulsion is a prerequisite for microencapsulation and therefore, an optimization of the US conditions always means a compromise between quality of the first emulsion on the one and protein degradation on the other hand. Therefore, with respect to the emulsion 25 W for 15 sec. was the tolerable limit of energy brought m the formulation which yielded in a degradation of approximately 50 %. Consequently, we searched for excipients, which were able to downsize protein degradation.
  • Fig. 2 shows the influence of these substances with respect to protein stabilization under the former optimized US condition.
  • erythropoetm e.g. erythropoetm
  • IGF-I another one
  • Bovme serum album snould be replaced by human serum albumin (HSA) to avoid lmmunological complications when used in human.
  • HSA human serum albumin
  • Gelatin is commonly used as plasma expander in humans (e.g. PhysiogelM and should consequently be of particular interest witn respect to safe formulation.
  • the entrapment efficiency does not correlate entirely with the stabilizing effects of the various excipients. While the mixtures BSA/Physiogel ® and BSA/PEG protected most efficiently the IGF-I under ultrasomcation, only moderate entrapment efficiencies were measured when they were co-encapsulated. We assume that these mixtures interfered physically with the IGF-I entrapment, thereby reducing the engulfment of the peptide.
  • the release profiles in Fig. 4 show a trionasic release pattern for the formulations carrie ⁇ througn, as observed often for proteins released from PLA/PLGA microspheres.
  • the three pnases were assigned to diffusion of peptide located near the microsphere surface (first phase, often called burst release), to ionic interactions between peptides and the PLA/PLGA chains that increase their negative charge density upon polymer nydrolysis (second phase with little release), and to a final, increased release due to polymer erosion and ⁇ issolution of low molecular weight PLGA fragments (third pnase) .
  • Physiogel ® acts in a known manner as a polymer hydrolysis modifying agent.
  • a high initial burst can be detected especially for the formulation made with BSA and Physiogel ® .
  • One aim of our work was to decrease the initial burst release by using variations of different excipients or by manipulating tne osmotic pressure of the outer phase during formulation. Nonetheless, while a certain amount of burst release might be favorable for bone repair, it seems very important that IGF-I action will be limited to 3 to 4 weeks. After this period of time, fracture healing will be advanced; reports from the literature also indicated that high systemic doses of IGF-I (200 ⁇ g/kg rat) over 17 days increased longitudinal and premstall growth, but suppressed trabecular bone formation in rats).
  • Tne first release peax or initial burst of bioavailaole IGF-I is a ⁇ vantagous in reducing the local inflammatory reaction.
  • a third peak after about 15 to 17 days is advantageous for fracture healing. In adult patients this third peak might be delayed up to until around day 30.
  • IGF-I release profiles suggest that 20- 30% of protein remained unreleased or undetected by RIA or fat cell assay.
  • Previous studies on protein release from PLGA microspheres have revealed that proteins may adsorb to remnant polymer fragments in the incubation. Further experiments are needed to elucidate the availability and fate of the undetermined amount of IGF-I. Further support for the biological activity of the released IGF-I was provided by the fat cell assay. This assay measures the glucose uptake of fat cells due to stimulation by IGF-I.
  • the amounts of released IGF-I measured by fat cell assay or RIA were generally comparable, exept for IGF-I released from the formulations made with NaCI in the outer W- phase with the W/O/W system. In these cases, the amounts measured by RIA were twice as those determined by fat cell assay. This might be ascribed to a disturbance of the glucose uptake by the fat cells due to an increased sodium concentration caused by entrapped and released NaCI from microsphere preparation. On the other hand, we can not exclude that the released IGF-I from these particles was less active than the IGF-I released from microspheres produced without NaCI.
  • the bi-, tri- or multiphasic release pattern of the composition is not based on a bi-, t ⁇ - or multiphasic release pattern of one single type of microcapsules or microspheres out on a mixture of at least two different types of monophasic microcapsules and/or microspheres.
  • Those microcapsules and/or microspneres exnio t sustained release of an effective amount of tne bioactive polypeptide over a period of at least 1 to 2 days.
  • the novel composition may contain the at least two different types of microparticles with known types of release kinetics in equal or unequal amounts. By including a higher portion of a particle of a certain type the the corresponding release peak can be increased. By varying the pro rata content of particles of different types, the height of the peaks, i.e. the amount of released protein, can be influenced, without influencing the timing of the release.
  • novel formulations represent a significant step towards the therapeutic use of IGF-I in controlled release formulations.

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Abstract

A novel pharmaceutical composition designed for sustained release of an effective amount of a drug over an extended period of time prepared in microcapsule or microsphere form is suggested. The composition comprises: at least one polypeptide which is a naturally occurring insuline like growth factor (IGF), a synthetically prepared material of the same type or synthetically prepared analogues of naturally occurring IGF;at least one stabilizing agent; at least one polymer hydrolysis modifying agent; and a biocompatible, biodegradable encapsulating polymer which is a poly(lactide-co-glycolide) copolymer. The lactide/glycolide molar ratio of the copolymer, its molecular weight, and the capsule diameter and the polymer hydrolysis modifying agent, are such that the composition exhibits sustained release of an effective amount of the polypeptide over a period of at least 3 to 4 weeks.

Description

SUSTAINED RELEASE COMPOSITION COMPRISING INSULINE LIKE GROWTH FACTOR
This invention relates to pharmaceutical compositions designeα for sustained release of an effective amount of a stabilizeα polypeptide and a process for preparing tne composition.
Efforts have oeen αevoted to identify favorable measures enhancing the formation of durable bone after fracture. This has led to the stuαy of factors capable to stimulate bone repair. The list of growth factors that nave a putative effect on the development and proliferation of different cell types has grown considerably. A large body of data from in vitro and in vivo studies has substantiated the importance of msulm- like growth factor 1 (IGF-I) in promoting fracture healing. Human Insulm-like growth factor I (hIGF-I) is a peptide hormone mediating the growth promoting effect of human growth hormone. Two effect mechanisms for hIGF-1 release exist: 1) production in the liver for endocrine action and ii) local production for paracπne action. In the context of joint biology, IGF-I seems to play an important local role in bone proliferation and bone healing after injury. Cell proliferation and matrix synthesis by chondrocytes and osteoblasts is promoted by IGF-I. Both cell types are largely responsible for the formation of the fracture callus. Interestingly, administration of IGF-I increases bone turnover in patients with low mineral density. Furthermore, tnere is evidence that IGF-I accelerates the normal healing of bone defects, even those which normally show heavily impaired healing. A typical role of IGF-I is to mediate the effect of growth hormone (GH) on skeletal growth. Although IGF-I is not a potent mitogen m bones, there are nigh affinity receptors for IGF-I on osteoblasts, and IGF-I can stimulate precsteoblast replication and provoke resting cells to proceed througn their cell cycles
3 . The temporal pattern of IGF-I gene expression (rat, mandibular osteotomy healing; revealed that tne protein is αpregulated 7 days after injury. The upreguiation of IGF I ana, additionally IGF II αuπng mandibu±ar bone heading unαerscores the importance of these growth factors in Done repair. Therefore, despite its relatively weak mitogenic properties, IGF-I may have significant anabolic activity on the skeleton and on poor or retarded bone repair. This s supported cy a vast set of data demonstrating the importance of IGF-I for Done growtn and fracture healing. Unfortunately, these studies snow such αiverse results that no general conclusion regarding the effect or IGF-I on fracture healing can presently be drawn.
The EP-A-0 ' 980 ' 273 discloses an implant made of a polmenc biodegradable base material for use in reconstructive osteosynthes s containing growth factors like IGF-I. The active ingredient has been worked into the implant in a way to aid bone growth in the area of the fracture. It is suggested to encapsulate the growth factors in a biodegradable polylactide material by means of "in water drying" of W/O/W emulsions. A huge number of biodegradable polymers have been described for controlled parenteral and mucosal drug delivery (e.g. J. Heller, Polymers for controlled parenteral delivery of peptides and proteins, Adv. Drug Delivery Rev. 10, 163-204, 1993) . The three most common methods for the production of microcapsules or microspheres are a) solvent evaporation/extraction, b) coacervation (or organic phase separation) and c) spray drying. Common to the three major methods is the dispersion of the aqueous protein soultion in an organic polymer solution, non- miscible with the organic phase. For αifferent proteins and also for antigens numerous solvents and emulsification methods have been described. However, the release dynamics of pharmaceutically active proteins enclosed m microcapsu es or microspneres are often unpredictable and uncontrollable (T.G. Park et al., Journal of Controlled Release, 211-222, 1995). Unfortunately most studies have dealt with protein release kinetics without examining the stability of the encapsulateα Drotem (T.G. Park et al. 1995 . The encapsulation of the growth factors as suggesteα in the EP- A-0'980'273 nas Deen snown to be much more efficient tnan any other previously known form of loading an implant with a growtn factor. However initial microspnere preparations according to known methoαs resulted n severe protein degradation with only a low percentage of the IGF-I remaining intact after encapsulation and/or release.
Due to a number of unfavorable conditions microencapsulation of protein drugs is generally critical for protein stability. Typically, exposure of proteins to organic solvents such as dichlormethane (DCM), cetones, or alcohols, to aqueous/ organic interfaces and to shear and cavitational forces necessary to form the W/O/W- emulsions may be rather detrimental to protein structure ana activity. These stress conditions may sometime lead to protein aggregation, as it has been described for growth hormone, or for insulin. It stands to reason that these effects are more abundant when the interface growths. It is therefore an objective of this invention to provide a process for preparing a pharmaceutical composition designed for sustained release of an effective amount of a drug over an extended period of time prepared in microcapsule or microsphere form wherein the composition comprises at least one polypeptide which is a naturally occurring insuline like growth factor (IGF), a synthetically prepared material of the same type or synthetically prepared analogues of naturally occurring IGF with a high effectiveness of encapsulation, while negative effects are averted. By providing a process which combines suitable process parameters and the use of advantageous auxiliary substances a high degree of polypeptide stabilty during the encapsulation process can be reacheα, wniie negative effects are averted.
A method of forming a pnarmaceutical composition, in accordance with one aspect of the invention, comprises mixing an aqueous stock solution containing IGF-I, a buffer solution, a polymer nydrolysis modifying agent and a protein stabilizing agent; emulgating said mixture in an organic solvent containing saic encapsulating polymer oy ultrasonication; aαding said W/O- dispersion to an aqueous PVA-solution to form a W/O/W- dispersion by mecnanical stirring; extracting the organic solvent; ana collecting, wasning and drying of the microcapsules and/or microspheres from this solution.
A pharmaceutical composition, in accordance with another aspect of the invention, comprises a naturally occurring msuline like growth factor (IGF), a synthetically prepared material of the same type or synthetically prepared analogues of naturally occurring IGF microencapsulated in tne presence of a protein staoilizing agent.
It has been found that a parenterally admimstrable therapeutic composition can be formed by encapsulating the protein with a lactide/glycolide molar ratio of the copolymer, its molecular weight, the capsule diameter, the capsule surface and the polymer stabilizing agent, being such that the composition exhibits sustained release of an effective amount of the bioactive polypeptide within 3 to 4 weeks showing a first peak after 12 hours to two days, or after about 6 to 10 days or after about 12 to 15 or after about 15 to 21 days (i.e. monophasic release pattern) .
It has oeen found that a parenterally admimstrable therapeutic composition can oe formed by microencapsulatmg the protein with a lactide/glycolide molar ratio of the copolymer, its molecular weight, the capsule diameter, the capsule surface and the polymer stabilizing agent, being such that the composition exhibits sustained release of an effective amount of the bioactive polypeptiαe over a peπoα of at least 3 to 4 weeks showing an initial burst and a second peak after aoout 6 to 10 days (i.e. bipnasic release pattern) .
It has been found that a parenterally aαministrable therapeutic composition can be formed by microencapsulatmg the protein witn a lactιαe/g_ycoιide molar ratio of tne copolymer, ts molecular weight, tne capsule diameter, tne capsule surface ana tne polymer staoiiizmg agent, σeing sucn tnat tne composition exhibits sustained release of an effective amount of tne bioactive polypeptide over a period of at least 3 to 4 weeics showing an initial burst and a second peak after about 6 to 10 days ana a third peak after about 15 to 17 days (i.e. tπpnasic release pattern) .
Further it has been found that a parenterally admimstrable therapeutic composition can be formed by mixing at least two different types of the above mentioneα microcapsules . By selecting and mixing for example three different types of "simple" monophasic microcapsules exhibiting peaks after 12 hours to two days, 6 to 10 days and 15 to 21 days a very complex release pattern can be achieved.
Furthermore, by microencapsulatmg the protein under favourable conditions a parenterally admimstrable therapeutic composition can be formed with up to 85% entrapment efficiency. Meaning that less than 15 % of the protein present in the initial stock solution is not encapsulated m a bioactive releasable form.
To answer the question how anabolic effects of IGF-I can promote the clinical enhancement of fracture neal g, it is a further objective of this invention to αevelop a sustained release composition for IGF, having a half-live m vivo of only 20-30 minutes .
The development of an IGF-I controlleα release composition useful in promoting restoration of bone defects by controlling ana maintaining IGF-I release in si tu over up to 10 weeks, preferably 3 to 4 weeks is a further objective of tnis invention .
It s another objective of the present invention to proviαe a pharmaceutical composition αesigned for sustained release of an effective amount of a proteinaceous drug over an extenαed peπoα of time prepareα m microcapsule or microspnere fcr wnere tne αrug is released pronounceα tri- or multiphasic release patterns.
Even though the invention is described witn a certain αegree of particularity, it is evident that many alternatives, modifications, and variations will oe apparent to tnose skilled in tne art in light of the foregoing disclosure. Accordingly, it is intended tnat all such alternatives, moαifications , and variations which fall within the spirit and the scope of the invention oe emoraced oy the defined claims.
The following figures form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be Detter understood by reference to one or more of these figures in combination with the detailed description of specific embodiments of the present invention presented herein. It shows
Fig.l: IGF-I degradation upon ultrasonic homogemzation of an aqueous IGF-I solution in dichlormethane phase (W/O) ;
Fig.2: influence of various excipients on IGF-I stability upon ultraso cation (25Watt, 15 seconds). The amounts of additives are given under Materials ana Methods. The error bars indicate standarα deviation with n=3;
Fig.3: entrapment efficiency of intact IGF-I m PLGA 50:50 microspheres . Co-encapsulation of various additives haα a strong stabilizing effect. The percentages of additives reppresent amount of soliα exc pient material with respect to polymer mass . The initial W/O- αispersion was ootamed by ultrasomcation at 25W for 15 s;
F g.4: in vi tro release profiles of IGF-I from PLGA 50:50 microspheres. The curves represent microspneres preparations containing various cc- encapsulateα additives: Percentages of additives represent amount of soliα experiment material with respect to polymer mass; and
Fig.5: the in vi tro release profiles of IGF-I from figure 4 in a single graph.
The invention will be further appreciated in light of the following example.
Example
Materials and Methods Materials
End-group uncapped Poly (lactide-co-glycolide) 50:50 (PLGA 50:50) with a M„ of approx. 14 kDa was purchased from Boehπnger Ingelheim ( Ingelheim-Germany, Resomer® RG502H) . Bovine serum albumin (BSA) was from Fluka, CH-Buchs, and human serum albumin (HSA) from the Swiss Red Cross, CH-Bern. Manmtol, β-cyclodextrm and trehalose were from Sigma-Aldrich, CH-Buchs, and msulm-like growth factor was kindly supplied by Chiron, Emeryville CA. Dichlormethane (DCM) and acetomtrile were purchased from Scharlau, CH-Tagertwil . Unless specified otherwise, all other substances used were of pharmaceutical or analytical graαe and purchased from Fluka, CH-Buchs. For radioimmunoassay (RIA) testing, an anti-IGF-I antibody previously produced in rabbits was used. The anti-rabbit γ- globulm (goat) from Novabiochem (CH-Laeufelfmgen) .
Microsphere preparation
A W/O/W solvent extraction-evaporation metnoα was used to prepare IGF-I loaded microspheres. Typically, 0.15 ml of internal aqueous phase consisting of 13.5 μg of IGF-I in 10 mM soαium succmate plus 140 mM sodium chloπαe of pH 6.0 were emulsified m 2 ml of a solution of 50 mg of PLGA 50:50 n DCM. For specific preparations, the internal W- pnase contained additional excip ents: 2.5 mg BSA, 2 mg solid material of Physiogel® (80 mg/ml of succmulated gelatin, Braun Medical (B.Braun Medical AG, CH-6020 Emmenbrucke) , 2.5 mg BSA -r 2 mg of solid material of Physiogel®, and 2.5 mg BSA + 12.5 mg PEG 400) Emuisification was achieved by ultrasomcation (50 W, 15 s). The obtained W/O-dispersion was poured into 30 ml of a 5 % (w/v) external aqueous solution of poly (vinyl alcohol) (PVA) to form a W/O/W-dispersion by mechanical stirring at 500 rpm for 1 mm. This W/O/W-dispersion was subsequently poured into 400 ml of de-iomzed water and stirred for 25 mm with a magnetic stirrer to extract the organic solvent. Afterwards, the particles were collected on a regenerated cellulose (RC) membrane filter of 1 μm pore size and washed 4 times with 100 ml of de-ionized water.
The particles were finally dried under reduced pressure (approx. 100 mbar) at room temperature for 7 h.
Stabilizing agents and stability study of IGF-I
To study the protective effect of various excipients on IGF-I stability, 0.3 ml aqueous IGF-I solution (75μg/ml IGF-I m 10 mM succmate buffer, pH 6) was emulsified in 1 ml DCM. The excipients 25% PEG, 3% BSA, 3% trehalose, 3% Manmtol, 5% β- cyclodextrm, 25% Physiogel® or combinations thereof (see Fig.l) were added to the aqueous phase. The W/O-emulsification was done in a PTFE tube using ultrasomcation (50 W, 15 s) . Afterwards, the phases were separated by centrifugation, ana the concentration of IGF-I in the upper phase was determined oy HPLC.
IGF-I content in the microspheres
In experiments, approx. 50 mg of microparticles were weigneα and dissolved in 0.3 ml of DCM in an Eppendorf cup (1.5 ml) . Then, 0.7 ml of acetone were addeα, ana the vials vortexed ana centrifugea at 14000 rpm for 5 mm (Eppendorf centrifuge 5415C) . The supernatant was removeα, ana 0.9 ml of a 3:1 acetone/ methylene chloride mixture was addeα. This wasmng procedure was repeated 3 times. Finally, the residue was dissolved in 0.1M acetic acid.
In vitro release studies
IGF-I release from 20-40 mg microspheres was conducted in 4 ml PBS of pH 7.4 in rotating borosilicate vials at 37°C and assayed by raαioimmunoassay . At regular intervals certain amounts of the medium was replaced by fresn buffer and analyzed by RIA, after separation of the particles and the supernatant by centrifugation at 3500 rpm for 10 mm. Furthermore, the pH was monitored and held constant at a pH of 7.4. Release experiments were performed in triplicate.
HPLC method
High-performance liquid chromatography (HPLC) was used to assay IGF-I. The system consisted of a A6000 computer interface (Merck,), a 6200A pump, L4250 UV and F 1050 fluorimetπc detectors, a A4000 automjector, and a sample cooler (all from Merck, CH-Zuerich) . Separation was performed on a Zorbax® 300SB CN-column (150*4.6 mm) at ambient temperature (30°C), using an isocratic system at a flow rate of 0.8mL/mm. The eluent was composed of 26% acetomtrile, 74% HPLC grade water, and 0.2 ml of tπfluoacetic acid per liter. After eacn run, the column was washed with 80% acetomtrile and 20% HPLC grade water. IGF-I was detected at 214 nm and quantified by measuring the peak area .
Radio immunoassay (RIA)
The radioim unoassay for IGF-I was carried out as αescribeα previously. Pure IGF-I served as standarα.
Measurement of microsphere size
Approximately 10 mg of microparticles were reαispersed in 2-3 ml distilled water containing 0.1% T een' 20 for severa_ minutes m an ultrasonic oath Branson) . The size was determined by ^aser diffractometry using a Malverr Mastersizer X (Germany) .
Fat cell assay (FCA)
IGF-I was determined a fat cell assay in tne presence of insulin antiserum (Zapf et al. 19801. Briefly, fat cells were obtained from epididymal fat paαs of 120-130 g male Zbz Cara rats by collagenase digestion. Uptake of 3H-Glucose was measured in a β-counter. Whale insulin (same ammo acid sequence as porcine insulin) was used as standard.
Results
The stability of IGF-I upon ultrasomcation (US) is shown in Figure 1. 0.3 ml of IGF-1 (cone. 75 μg/ml) solution m 1 ml DCM/acetone (3:1, v/v) were sonicated to form the primary W/O emulsion. Ultrasomcation with 50 W for 15 s caused severe protein degradation, with only 36% of IGF-I remaining intact. After ultrasomcation with 25 W for 15 s, 48% of IGF-I remained intact. Milder US-conditions of 25 W for 5 s or 10 W for 10 s or the use of a vortex mixer were insufficient for emulsification . Thus, IGF-I degraded substantially under the homogemzation conditions necessary to form the primary W/O emulsion. We therefore studied the protection effect of various excipients such as sugars, polyalcohois, cyclodextrmes or other proteins on IGF-I. As predictions of protein stability in the presence of excipients are impossible, the effect of putative stabilizers on the specific protein under investigation must be assessed experimentally.
While polyalcohois, sugars and cyclodextrm did not protect IGF-I in comparison to the experiment without additive (column 1), 3% BSA protected 83% of this protein (Fιg.2^. Physiogel (8 mg succ ulateα gelatin in 100 μL/ 0.3 ml IGF solution; protected 90% of IGF-I under ultrasomcation. PEG 400 protected IGF-I fully unαer the conditions used. Comoinations of 3s- albumin with e tner Pnysiogel or PEG 40C (botn at 100 μL/ 0.3 ml) protect IGF-I fully during the W/O-emulsification under ultrasomcation.
Table 1:
% released % released Days IGF-I (RIA) IGF-I (FCA)
BSA 5 29 24
" ΪSA~+~Physiogel 0.3 "37 40
6.7 60 64
BSA + Physiogel + 2% NaCI 0.2 27 14
BSA + Physiogel + 5% NaCI 0.2 28 16
To assess the influence of the polymeric material, IGF-I was microencapsulated by the solvent evaporation technique at drug loading levels in the range of 0.2 to 0.7 % (w/w) . Batch sizes of 30 to 150 mg polymer yielded 72 to 86 % of dried microspheres. Particle size was 61 ±11 μm. Accurate determination of the protein content in microspheres was rather critical, as already pointed out by others. IGF-I was extracted from the microspheres by dissolving them in DCM. The in DCM insoluble IGF-I was then separated using centrifugation . Separation by filter membranes gave unreliable results due to strong adsorption of IGF-I to the filter materials. The encapsulation efficiency, defined as the ratio of actual over theoretical IGF-I content, was between 23 and 81%, depending on the co-encapsulation of various excipients (Fig. 3) .
If IGF-I was not protected by co-encapsulated additives or stabilizers, it degrades as indicated by HPLC. Without stabilizers, the apparent encapsulation efficiency amounted to only 23% (column 1). By contrast, approx. 80% entrapment efficiency was measured in the microspheres containing either 5% of BSA or 4% of Physiogel® (Column 2 and 3 respectively) ; percentages of additives represent amount of solid excipient material with respect to polymer mass. When mixtures of 5% 3SA and 4% Phvsioσel® (column 4) or of 5% BSA and 25% PEG (column 5) were co-encapsuiateα, intermediate entrapment efficiencies of 52 and 30 % were determined.
Figure 4 shows the m vi tro release profile of IGF-I from PLGA microspheres proαuced with different excipients. Hence, the initial burst of tne formulation witn BSA ana Physiogel® is roughly 40% while all other formulations show smaller bursts. Especially the low one of the formulation produced with 5% NaCI in tne outer pnase is noticeable. All formulations show a more or less attenuated typical tπpnasic release pattern. While the formulation with Physiogel® alone enters the third phase at day two to three the formulation witn BSA and Physiogel® and 2% NaCI in the outer phase enters it at day 5. The other formulations are more retarded especially the formulations with BSA and Physiogel® and 5% NaCI and the one with BSA alone. IGF- I released during the third phase was approx. 30-50%. Only the combination of BSA and Physiogel® m the microspheres led to a poor release of IGF-I in this phase of approx. 10 %. The sheerness of the third phase was very similar for formulations made with BSA and Physiogel® and 5% NaCI in the outer phase and the one just made with BSA and exhibited a continuous release lasting over 5 days. In contrast to this the third phase for the formulation with BSA and Physiogel® and 2% NaCI in the outer pnase or Physiogel® alone only lasts for two to three days. The total IGF-I released from the matrix lies between 55 and 75%. HPLC and RIA analyses suggested that IGF-I released from the microspheres was intact. The full biological activity of IGF-I released from the microspheres was indeed confirmed in a fat cell assay (Tab. 1) . When NaCI s added during the preparation, the released IGF-I indicated by RIA is approx. twice as mucn as determined by FCA. In all other cases there is an excellent agreement between measurements by RIA and by the fat cell assay of the amounts of IGF-I released during the in vi tro study. Discussion:
The design of the here αescrioeα delivery system for IGF-I was guided by safety considerations in view of an eventual use in humans and by reasonably fast degradation of tne system after implantation. Thus, low molecular weight PLGA 50:50, which has a good safety record and degrades within approximately 1 month, ano additives that are generally regarded as safe in parental administration have been selected. Microencapsulation of IGF-I in PLGA 50:50 was performed by the so called W/O/W- solvent extraction method, because this method is best suited for preparing small amounts of microspheres, as planned in this work .
If IGF-I is sonicated with relatively force conditions it shows heavy degradation of approximately 60 to 70 %. However, a sufficient first W/O emulsion is a prerequisite for microencapsulation and therefore, an optimization of the US conditions always means a compromise between quality of the first emulsion on the one and protein degradation on the other hand. Therefore, with respect to the emulsion 25 W for 15 sec. was the tolerable limit of energy brought m the formulation which yielded in a degradation of approximately 50 %. Consequently, we searched for excipients, which were able to downsize protein degradation.
Fig. 2 shows the influence of these substances with respect to protein stabilization under the former optimized US condition. Unfortunately the protecting influence can not be assessed theoretically. It is interesting, that a sometimes-good stabilizing effect with one protein (e.g. erythropoetm) does not exhibit an effect on another one (e.g. IGF-I) . IGF-I is fully protected by BSA, Gelatin, its combinations, PEG and the combination of the latter with BSA. In view of human use, Bovme serum album snould be replaced by human serum albumin (HSA) to avoid lmmunological complications when used in human. Gelatin is commonly used as plasma expander in humans (e.g. PhysiogelM and should consequently be of particular interest witn respect to safe formulation. Especially the necessary nign concentrations of PEG 400 (25%) were critical witn respect to clinical safety. E.g. topical interactions witn biological memoranes of tnis emulgator can not be excluded. Therefore, we focussed on the usage of BSA ano gelatin.
After the optimization of the protection of IGF-I to US induced encumbrance the next step was the investigation of the behavior during microencapsulation, release and entrapment efficiency. Considering that incomplete peptide entrapment results from both physical losses of material during microencapsulation ana from degradation/aggregation of the peptiαe, co-encapsulated excipients will correspondingly affect ooth these quantities. Very encavagingly , the co-encapsulated excipients all improved the IGF-I entrapment, which must be ascribed to their stabilizing, effect during microencapsulation. This is in perfect agreement with the previous stability experiments under ultrasomcation. Conversely, the entrapment efficiency does not correlate entirely with the stabilizing effects of the various excipients. While the mixtures BSA/Physiogel® and BSA/PEG protected most efficiently the IGF-I under ultrasomcation, only moderate entrapment efficiencies were measured when they were co-encapsulated. We assume that these mixtures interfered physically with the IGF-I entrapment, thereby reducing the engulfment of the peptide.
The release profiles in Fig. 4 show a trionasic release pattern for the formulations carrieα througn, as observed often for proteins released from PLA/PLGA microspheres. The three pnases were assigned to diffusion of peptide located near the microsphere surface (first phase, often called burst release), to ionic interactions between peptides and the PLA/PLGA chains that increase their negative charge density upon polymer nydrolysis (second phase with little release), and to a final, increased release due to polymer erosion and αissolution of low molecular weight PLGA fragments (third pnase) . In the slightly acidic microenvironment inside the microspneres IGF-I witn a pi of 8.2 is positively cnarged and interacts througn polar forces with the negativel cnarged polymer or its degraαation products . Physiogel® acts in a known manner as a polymer hydrolysis modifying agent.
A high initial burst can be detected especially for the formulation made with BSA and Physiogel®. One aim of our work was to decrease the initial burst release by using variations of different excipients or by manipulating tne osmotic pressure of the outer phase during formulation. Nonetheless, while a certain amount of burst release might be favorable for bone repair, it seems very important that IGF-I action will be limited to 3 to 4 weeks. After this period of time, fracture healing will be advanced; reports from the literature also indicated that high systemic doses of IGF-I (200 μg/kg rat) over 17 days increased longitudinal and premstall growth, but suppressed trabecular bone formation in rats). Furthermore, a recent paper reports that local infusion of 50 ng/day of IGF-I over 14 days m adult rats increased the trabecular bone thickness (femur) by 58%, and bone formation rate by 81%. Indeed, IGF-I gene expression was found maximal 7 days after an osteotomy. A secondary IGF-I release pulse between days 6 and 10, as suggested by the present data, might be beneficial with respect to enhanced fracture healing. The secondary IGF-I release from PLGA 50:50 microspheres was marginal for the formulation with co-encapsulated BSA + Physiogel®. In contrast, all other formulations revealed a much more pronounced secondary pulse, amounting to 30% (BSA + Physiogel®, with 2% NaCI in the outer w-phase) to 40% (Physiogel® alone) of the total dose. Interestingly, the time course of release depended strongly on the co-encapsulateα excipients. The most prolonged IGF-I release for 13 days was obtained with the microspheres containing co-encapsulated BSA only or BSA + Physiogel® and prepared with 5% NaCI m the outer W-phase These formulations may serve as a reservoir enabling continuous IGF-I release over two weeks .
Although optimal IGF-I release kinetics for enhanced bone healing is still a matter of speculation, endocrmologists favor a nigh initial dose for the first 12 hours to 2 days followed by a second sustained dose between days 6 and 10. Tne first release peax or initial burst of bioavailaole IGF-I is aαvantagous in reducing the local inflammatory reaction. A third peak after about 15 to 17 days is advantageous for fracture healing. In adult patients this third peak might be delayed up to until around day 30.
Some of the in vi tro release profiles measured according to this example satisfy this duration regimen. However selection of a specific formulation or of a microsphere mixture was done done on the basis of performance in bone in animals. IGF-I release profiles suggest that 20- 30% of protein remained unreleased or undetected by RIA or fat cell assay. Previous studies on protein release from PLGA microspheres have revealed that proteins may adsorb to remnant polymer fragments in the incubation. Further experiments are needed to elucidate the availability and fate of the undetermined amount of IGF-I. Further support for the biological activity of the released IGF-I was provided by the fat cell assay. This assay measures the glucose uptake of fat cells due to stimulation by IGF-I. The amounts of released IGF-I measured by fat cell assay or RIA were generally comparable, exept for IGF-I released from the formulations made with NaCI in the outer W- phase with the W/O/W system. In these cases, the amounts measured by RIA were twice as those determined by fat cell assay. This might be ascribed to a disturbance of the glucose uptake by the fat cells due to an increased sodium concentration caused by entrapped and released NaCI from microsphere preparation. On the other hand, we can not exclude that the released IGF-I from these particles was less active than the IGF-I released from microspheres produced without NaCI.
As already indicated above in an composition according to another aspect of this invention the bi-, tri- or multiphasic release pattern of the composition is not based on a bi-, tπ- or multiphasic release pattern of one single type of microcapsules or microspheres out on a mixture of at least two different types of monophasic microcapsules and/or microspheres. Those microcapsules and/or microspneres exnio t sustained release of an effective amount of tne bioactive polypeptide over a period of at least 1 to 2 days. The lactide/glycolide molar ratio of the copolymer, its molecular weight, the capsule diameter, the capsule surface and tne polymer stabilizing agent, being such that the release peak occurs as an initial burst or is delayed for any period of 3 to 30 days. By increasing the degree of cristallimty of the copolymer in the microcapsules or microspneres the release oeaκ can oe delayed, i.e. pushed to the right in a graphic view. By selecting an end-group uncapped low molecular weight poly (D, L-lactide-co-glycolide) 50:50 for the procuction of a first type of capsules or spheres and an end-group uncapped low molecular weight poly (D, L-lactide-co-glycolide) 75:25 for a second type of capsules or spheres and subsequently mixing both types of capsules or spheres one may for example acheive this effec .
The novel composition may contain the at least two different types of microparticles with known types of release kinetics in equal or unequal amounts. By including a higher portion of a particle of a certain type the the corresponding release peak can be increased. By varying the pro rata content of particles of different types, the height of the peaks, i.e. the amount of released protein, can be influenced, without influencing the timing of the release.
The novel formulations represent a significant step towards the therapeutic use of IGF-I in controlled release formulations.

Claims

claims
1. A pharmaceutical composition designed for sustained release of an effective amount of a drug over an extended period of time prepared in microcapsule or microsphere form wnerem the composition comprises: at least one polypeptide which is a naturally occurring insuline like growth factor (IGF), a synthetically prepared material of the same type or synthetically prepared analogues of naturally occurring IGF; at least one stabilizing agent; at least one polymer hydrolysis modifying agent; and a biocompatible, biodegradable encapsulating polymer which is a poly (lactide-co-glycolide) copolymer; the lactide/glycolide molar ratio of the copolymer, its molecular weight, and the capsule diameter and the polymer hydrolysis modifying agent, being such that the composition exhibits sustained release of an effective amount of the polypeptide over a period of at least 3 to 4 weeks.
2. A pharmaceutical composition according to claim 1 wherein the at least one stabilizing agent is an albumin selected from naturally occurring albumin, recombmant albumin, synthetically prepared material of the same type or synthetically prepared analogues of naturally occurring albumins .
3. A pharmaceutical composition according to claim 2 wherein the albumin or albumins are selected from the group of human albumins, preferably naturally occurring numan serum albumin (HSA) , bov e or other mammal or other verteorate serum albumins.
4. A pharmaceutical composition according to claim 2 or 3 wnerem the stablizing agent comprises 1 to 15% albumin or 10 to 35 - poly (ethylenglycol) (PEG1 or 5 to 70% pnysioge .
5. A pharmaceutical composition according to claim 2 or 3 wherein the stablizmg agent comprises 3% albumin or 25% poly (ethylenglycol) (PEG) or 25% Physiogel
6. A pharmaceutical composition according to claim 1 characterized in that the poly (lactide-co-glycolide) copolymer is an end-group uncapped low molecular weight poly (D, L-lactide-co-glycolide) 50:50.
7. A pharmaceutical composition according to one of the claims 1 to 6 characterized that the microcapsules or microspheres exhibit sustained release of an effective amount of the bioactive polypeptide showing a biphasic or triphasic release pattern.
8. A pharmaceutical composition according to claim 7 characterized that the microcapsules or microspheres exhibit sustained release of an effective amount of the bioactive polypeptide over a period of at least 3 to 4 weeks showing an initial burst and a second peak after about 6 to 10 days and a third peak after about 12 to 15 or 17 days .
9. A pharmaceutical composition according to one of the claims 1 to 6 comprising at least two types of microcapsules and/or microspheres each type exhibiting monophasic, biphasic or triphasic release of an effective amount of the bioactive polypeptide, whereby the mixture of the at least two types of microcapsules and/or microspheres results in a release pattern showing at least one distinct release peak for each type of microcapsules and/or microspheres resulting m an at least biphasic release pattern of the released protein for the composition.
10. A process for preparing a composition of any one of the preceding claims comprising: mixing an aqueous stocκ solution containing IGF-I, a buffer solution, and a protein stabilizing agent; emulgatmg said mixture in an organic solvent containing said encapsulating polymer by ultrasomcation; whereby the adding said W/O-dispersion to an aqueous PVA-solution to form a W/O/W-dispersion by mechanical stirring; extracting the organic solvent; and collecting, washing and drying of the microcapsules and/or microspheres from this solution.
11. A process according to claim 10 characterized m that the buffer solution is 10 mM sodium succinat/ 140 mM NaCI pH 6.0 for the inner phase.
12. A process according to claim 11 characterized in that a protein stablilizing agent according to claims 2 to 5 is utilized.
13. A process according to claim 10 characterized in that the ultrasomcation is
14. The use of a pnarmaceutical composition according to one of the claims 1 to 9 for the manufacture of a medicament for local application orthopedic treatment of bone healing.
PCT/CH2000/000074 2000-02-09 2000-02-09 Sustained release composition comprising insuline like growth factor WO2001058426A1 (en)

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PCT/CH2000/000074 WO2001058426A1 (en) 2000-02-09 2000-02-09 Sustained release composition comprising insuline like growth factor

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Cited By (1)

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Publication number Priority date Publication date Assignee Title
WO2009005718A1 (en) * 2007-06-28 2009-01-08 Surmodics, Inc. Polypeptide microparticles having sustained release characteristics, methods and uses

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WO1999024061A1 (en) * 1997-11-07 1999-05-20 Chiron Corporation Method for producing igf-1 sustained-release formulations
WO2000000180A1 (en) * 1998-06-29 2000-01-06 White Spot Ag Utilization of growth factors for the production of medicaments

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EP0442671A2 (en) * 1990-02-13 1991-08-21 Takeda Chemical Industries, Ltd. Prolonged release microcapsules
WO1999024061A1 (en) * 1997-11-07 1999-05-20 Chiron Corporation Method for producing igf-1 sustained-release formulations
WO2000000180A1 (en) * 1998-06-29 2000-01-06 White Spot Ag Utilization of growth factors for the production of medicaments

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Title
DATABASE CHEMABS [online] CHEMICAL ABSTRACTS SERVICE, COLUMBUS, OHIO, US; YUKSEL E, ET AL.: "De novo adipose tissue engineering via polylactoglycolic acid/polyethylene glycol microsphere delivery of insulin and insulin-like growth factor-1", XP002150455, retrieved from STN Database accession no. 132:176052 CA *
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009005718A1 (en) * 2007-06-28 2009-01-08 Surmodics, Inc. Polypeptide microparticles having sustained release characteristics, methods and uses

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