IE62796B1 - Medicinal emulsions - Google Patents

Description

FSSXD GF BWHCg The present invention concerns pharmaceutical compositions of hydrophobic drugs being in the form of an oil-in-water emulsion. The pharmaceutical compositions provided by the present invention show an outstanding long term stability and, in addition, in various forms of administration they also have sustained release characteristics. These pharmaceutical compositions when comprising a heat resistant drug are also remarkably stable to sterilisation by autoclaving.

BACTSSBXW OF SOE ZNVENTSCiB SSSD PRIOR ART Relevant prior art to the subject of the present invention may be found in the following publications: 1) U.S. Patent No. 3,172,816. 2) EP-A2-214561. 3) EP-A3-215313. 4) Benita, S., Friedman, D. and Weinstock, M. (1986), International Journal of Pharmaceutics, 30: 47-55 ) Singh, M. and Ravin, J. (1986), J. Parenteral Sci. Technol. 37: 34-41. 6) Von Dardel, 0., Mebius, C. and Mossberg, T. (1976), Acta Anaesth. Scand. 20:221-224.

* The utilization of pharmaceutical compositions in the form of emulsions of drugs having low aqueous solubility is well known in the art. However, as a rule such compositions are of low stability due to fast phase separation between the oil and the water phases, which is further enhanced by the hydrophobic drugs for which the emulsions serve as carriers.

I Many hydrophobic drugs are important for various medical treatments, but since they are relatively unstable and insoluble in wafer their most useful form of administration Is by way of an oil-in-water emulsion-type composition, in which the drug is dissolved in the oil phase. This is in fact the only practical way by which such hydrophobic drugs can be administered intravenously.

In accordance with the prior art stability of compositions of this type was unsatisfactory since as stated above, the hydrophobic drugs destabilize such compositions. Another drawback of prior art emulsion type compositions is that they tend to lose their stability when they are sterilized in an autoclave which Is the most efficient and least costly way of sterilising such compositions. During autoclaving the oily droplets of the emulsion coalesce and consequently creaming and/or phase separation occurs. This therefore necessitated hitherto the use of other forms of sterilization such as filtration as described, for example, in EP-A2-214501 and EP-A3-215313.

US-A-4115513 discloses emulsions containing bile acids and fatty acid glycerides having 12-22 carbon atoms.

If is the object of the present invention to provide compositions of the oil-in-water type emulsions containing hydrophobic drugs, which are stable over prolonged storage and furthermore where the drug is heat resistant, ar© capable of being sterilized by autoclaving without a change in their properties or loss of their stability. If is a further object of the present invention to provide such compositions for parenteral, oral, ocular and topical administration of said drug. - 3 In accordance with the Invention it has surprisingly been found that oil-in-water type emulsions of a hydrophobic drug which comprise an oily carrier being a medium chain triglyceride (MIT) oil optionally in combination with vegetable oil, phospholipids, non-ionic surfactants and an ionic surfactant being a bile-duct surface active agent, cholic acid, or deoxycholic acid or a surface active derivative or salt thereof are surprisingly more stable than prior art lipophilic drug-containing emulsions both in prolonged storage and in autoclaving.

The improved stability of the compositions in accordance with the invention was found to be caused by a syngergism which exists between the various ingredients, i.e. between said oily carrier, phospholipids, non ionic surfactant and said ionic surfactant.

In the following specification and claims all indication of percent (¾) are by weight (w/v - weight of ingredient/volume of entire composition). All concentrations given below should be understood as standing each by itself and not cumulative.

The invention provides a pharmaceutical composition being an oil-in-water type emulsion comprising an effective amount of a hydrophobic drug, characterised in that it comprises about 3-50% of an oily carrier consisting of MGT oil optionally in combination with vegetable oil, about 0.05-20% of a phospholipid, about 0.03-10% of a nonionic surfactant, and about 0.05-10% of an ionic surfactant selected from the group consisting of ionic bile-duct surface active agent, cholic acid, and deoxycholic acid, and their surface active derivatives and their salts.

An oil-in-water type emulsion generally comprises tiny oily droplets comprising the oily carrier (to be referred to hereinafter as the oily phase”) which are suspended in an agueous solution (to be referred to hereinafter as the aqueous phase). The oily droplets are surrounded by a stabilising inter facial film (to be referred to hereinafter for the sake of convenience as the '’intermediate phase) formed by the phospholipids, the nonionic surfactant and the said ionic surfactants.

MCT oil has many advantages over vegetable oil, amongst which are the following: lower susceptibility to oxidation; having a specific density of 0.94-0.95 which is higher than that of vegetable oil and which is close fo that of water thus facilitating the obtaining of a stable emulsion; being less hydrophobic than vegetable oil and therefore enables achieving higher concentrations of the drug dissolved therein; having a lower viscosity which again enables obtaining a higher concentration of the oily phase in the composition without substantially increasing 15 its viscosity.

On the other hand, vegetable oil has the advantage over MCT oil in its lower price. Thus, although the use of MCT oil by itself as the oily carrier is generally preferred in accordance with the invention, it may at times be 2q practical to substitute some of it with vegetable oil.

Compositions in accordance with the present invention are suitable for topical, parenteral, ocular and, oral administration of lipophilic drugs. Preferably the compositions are supplied in unit dosage form. Where a composition of the present invention is to be used for parenteral administration, it must be sterile, which sterilisation is preferably performed by autoclaving. The Ingredients in compositions to be used for parenteral administration will have to be of Injection grade and medically approved for such administration.

An Injectable composition should not be too viscous. As a rule, the viscosity of an emulsion increases, wifh an increase of the relative proportion of the non aqueous phase namely the oily and the intermediate phases, which comprise the oily carrier, phospholipids, non-ionic surfactant, said Ionic surfactant and the hydrophobic drug.

It is accordingly preferred, in. accordance with the present Invention, that the relative proportion of the non aqueous phase in injectable compositions, should not exceed about %. Xt is even more preferred, in accordance with the present invention, that ths relative proportion of the non » aqueous phase In injectable compositions he below about 25%. » On the other hand, topical compositions should preferably be viscous and to this end the relative proportion of the non-aqueous phase should preferably be above about 30%.

The preferred ranges of Ingredients of injectable pharmaceutical compositions according to the invention are; oily carrier - about 10-20%; phospholipid ~ about 0.5-2%, Q.75%-2% being particularly preferred; non-ionic surfactant - about 3-10% or about 0.5-3%; said ionic surfactants about 0.05-5% or about 0.3-10%, 0.5-2% being particularly preferred; drug - about 0.02-2%. In one embodiment, the relative amount of said ionic surfactants is about 4-6.6% when the amount of non-ionic surfactants is about 3-10%.

Again, these preferred ranges are to be understood as standing each by itself and ar® not cumulative.

The preferred pH of the aqueous phase of the composition of the invention is about 5.0-8.5, while 6.0-8.0 being more preferred, especially for parenteral administration.

Examples of MCT oil to be used in the compositions of the present invention are TCM (trade name Societe des Oleagineaux, France), Miglyol 812 (trade name 30 Dynamit Nobel, Sweden).

Examples of vegetable oil which may be used in the compositions of the present Invention are soybean oil, cotton seed, oil, olive oil, and sesame oil.

Examples of phospholipids which may be used in 35 compositions according to the invention are lecithins; EPIKURON or OVOTHINT60 (trade name - both manufactured by Lucas Meyer, Germany; which are mixtures of mainly phosphatidylcholine and phosphatidylethanolamine from a natural source, such as purified egg yolk phospholipids (for the OVOTHIN series) and such as soybean oil phospholipids (for the epikurqn series); a purified phospholipid mixture; Phospholipids Ξ-80 (trade name ~ manufactured by Lipoid KG.

Ludwigshafen, FRG).

An example of a non-Ionic surfactant which may be used in compositions according to the invention is a poloxamer (PLURONIC F-68 BASF, Ludwigshafen, FRG), which is a copolymer of polyoxyethylene and polyoxypropy lene.

Examples of said ionic surf actant to be used in compositions according to the invention are cholic acid and deoxycholic acid and surface active derivatives and salts thereof, which may be obtained commercially (Sigma, St. Louis, MO., U.S.A.). Preferred are cholic acid and dexoycholic acid and their sodium salts, deoxycholic acid and its sodium salt being particularly preferred.

The ionic surfactants used in accordance with the invention are anions of relatively weak acids and may thus associate with protons to become electrically neutral when the pH Is reduced. Since these substances are surface active in their anionic state, the pH during preparations should be such in which the acid Is dissociated into the anions and protons, I.©, the pH should have a higher value than the pKa (pKa - the pH In which half of th© acid is dissociated). Xt was found however that after the composition had already been prepared, there was no reduction in stability even upon lowering of the pH.

Th® pharmaceutical compositions of the present invention preferably also comprise a preservative such as methyl-, ©thyl-, propyl- and butylparaben which are medically accepted for parenteral administration. However, very often in accordance with the invention preservatives will not be required since the compositions may be sterilised by autoclaving without essentially reducing their stability. If desired, the pharmaceutical compositions of - 7 the present invention may also comprise an osmotic pressure regulator such as mannitol or glycerin, glycerin being preferred for parenteral administration and mannitol for oral administration. The compositions of the present invention may also comprise an antioxidant such as a-tocopherol.

The compositions of the present invention are suitable for the administration of hydrophobic drugs, i.e. drugs having a low water solubility- Examples of such drugs are: Hydrophobic or lipophilic antibiotic drugs sueh as amphotericin 3; hydrophobic and lipophilic narcotic drugs such as alkaloid bases, e.g. morphine-base; hydrophobic benzodiazepines such as diazepam, fluphenazine deconoate and lorazepam; non-steroidal anti-inflammatory lipophilic drugs such as piroxicam and indomethacin; lipophilic steroids such as progesterone and testosterone propionate; lipophilic azoles such as miconazole and clotrimazole; lipophilic polypeptides such as cyclosporine; lipophilic sterols such as deoxycortone and calciferol; lipophilic cephalosporin.es; dimercaptol., Where the drug in such compositions is Amphotericin 3, its concentration is preferably about 0-015 - 0.15%, about 0.075% being particularily preferred- Were the drug in said composition is morphine--base, its concentration is preferably about 0-2-2%. Where the drug in said composition Is either diazepam or Indomethacin, its concentration is preferably about 0.1-1%, about 0.4-0.5% being especially preferred. Where the drug in said composition is ciclosporlne, its concentration is preferably about 2-5%. Where the drug in said composition is miconazole, its concentration is preferably about 1-3%.

Generally, the oily droplets in the oil-in-water emulsion for medical use should preferably be small, i.e. below about 1 pm, preferably below 0.5 pm end desirably below 0.2 pm, since the smaller the droplets, the more stable in storage is the emulsion. The droplet size is furthermore of particular importance if the emulsion is to be used for parenteral administration, and especially for intravenous injections, since large droplets will not readily pass through small blood capillaries. The compositions of tha invention are particularly suitable for obtaining such small oily droplet.

The compositions of the present Invention may be prepared by a number of ways. By one preparation mode, an agueous solution and an oily solution are separately prepared, the aqueous solution comprising the non-ionic surfactant, the said ionic surfactant end the phospholipids and optionally also en osmotic pressure regulator and a preservative, and the oily solution comprising the said oily carrier, the hydrophobic drug and optionally also an antioxidant. By e slight modification of this mode, th® aqueous solution is prepared from two a priori prepared solutions, a first, alcoholic, solution containing the said ionic surfactants and th® phospholipid and a second solution containing in water the non-ionic surfactant and if desired also the other optional ingredients mentioned above. The said aqueous solution Is then prepared by mixing the first ©nd the second solution, then removing the alcohol, for example by evaporation, to yield the said aqueous solution. This modified mode is suitable for the preparation of composition of the invention in which the drug Is for example diazepam or miconazole and the like.

The aqueous solution and the oily solution are then mixed with one another. However, the so-obtained mixture does not yet consist of sufficiently small droplets, the sis© of which (obtained after mixing with a magnetic stirrer) Is about 10 pm. The droplet size of the Inventive composition may then be decreased by the use of emulsification equipment such as Ultra Turrax (Jankl and Kunkel, Staufen, FRG), which yields droplets having an average diameter of about 1.1 pm, or of © high shear mixer, e.g. Polytron (Kinematics, Lucerne, Switzerland) which yields droplets having1 an average diameter of ©bout 0.65 pm.

Especially small droplets are obtained in the inventive compositions when utilising a two-stage pressure homogeniser in which the crude dispersion is forced under high pressure through the annular space between a spring loaded valve and the valve seat, the second stage being in tandem with the first so that the emulsion is subjected to two very rapid, dispersion processes. An example of such an apparatus is the Gaulin Homogeniser (APv Gaul in, Silver sum, The Netherlands). Use of such an apparatus In accordance with the invention yields compositions in which the droplets have an average diameter of about 0.27 pm with a relatively small deviation.

Even smaller droplets may be obtained in accordance with the invention when the emulsification precess combines the use of both a Polytron-type high shear mixer followed by homogenisation. The droplet sise which is obtained In such a combination Is about 0.1-0.15pm. Achieving of such a droplet sise is highly important because of tha profound, affect this has on the increase in the composition’s stability and such is a result of both the ingredients used for the preparations of the composition, i.e. MCT oil and optionally vegetable oil, phospholipid, non-ionic surfactant and said ionic surfactant as well as the method, of preparation as described, above.

The present invention provides also a novel mode (to be referred to hereinafter as the inventive mode) for the preparation of the above compositions. The inventive mode is particularly suitable for the preparation of compositions in accordance with the Invention in which the drug is both hydrophobic and has a poor oil solubility, i.e. drugs which are present in the compositions predominantly in the intermediate phase. However, it should be noted that the inventive mode, as will be explained below, is suitable also for the preparation of compositions of the invention in which the hydrophobic drug Is lipophilic, namely oil soluble end thus present In the compositions predominantly in the oily phase.

In accordance with the inventive mode the compositions are prepared by mixing together a liposome mixture and an oily mixture, each one prepared separately beforehand. The liposome mixture comprises all the ingredients which In the final composition do not form part of the oily phase, namely the phospholipids, the non-ionic surfactant, the said ionic surfactant, and, if desired, also the optional osmotic pressure regulator and the preservative. Where the drug has a poor oil solubility, such ©s Amphotericin 3, it is also included in the liposome mixture. The preparation of the liposome mixture from these ingredients may be carried out by means known per se.

The oily mixture comprises the said oily carrier and, if desired, also the optional anti-oxidant. Where the drug is lipophilic, it Is also Included In the oily mixture.

After the liposome mixture Is mixed together with the oily mixture, .an emulsion is formed having relatively large droplets, e.g. about 10 pm, which Is further processed in a similar manner as described above in connection with the first preparation mode, until an emulsion having fine homogeneous droplets is obtained.

Compositions of the present Invention which contain heat resistant drugs remarkably withstand, sterilization in an autoclave. Such sterilization is easier to perform and more practical on industrial scales, than sterilization by filtration as described in EP-A2-214501 and EP-A3-245313. However, where the drugs are heat sensitive, such as anphotericin 3, standard aseptic conditions should be employed.

PESQRIPTXSSS OF SO^S SFECXFIS In the following· Examples, the preparation of some specific compositions according to the present invention is described, it being understood that these Examples ©re for illustrative purposes only. pgsangTSiaN of 'ass kwss In the following description, reference will et times be made to the annexed drawings in which: Fig. 1 is a schematic representation of the precess for extracting pure phospholipids from crude egg yolk phospholipids; Fig. 2 is a schematic representation of an emulsion preparation process; Fig. 3 shows droplet sise distribution in a composition not containing any drug (a) and in a composition containing the drug amphotericin B (b); Fig. 4 shows the droplet size distribution after three months storage at 4eC of compositions containing the drug amphotericin 3 (a) and compositions containing no lipophilic drug (b).

Fig. 5 shows the survival with time of Candida albicans infected mice after injection of Fungizone (trade name), an amphotericin 3 emulsion in accordance with the Invention and of saline.

EWEgMiSffT&L· .«SaSCW Measurement of emulsion properties in tests reported in some of the following Examples was performed as follows: A. Analysis of Particle Size The droplet sise distribution of the amphotericin 3 emulsions was determined by two complementary methods, namely by the photon correlation spectroscopy (PCS) using a computerised laser light scattering apparatus, considered the most appropriate for studying droplet size below 1 pm (Malvern system, Malvern, England), and the computerized laser inspection system which can measure droplet sizes above Chopra (Galai Cis-1, Migdal Haemek, Israel). In the Malvern system, each emulsion sample was diluted to th® appropriate concentration with a filtered isotonic solution (2.25% glycerin in water) before measurement at 25°C. Duplicate samples were taken and each sample was analysed 10 times. In the Galai system, the samples were also diluted with 2.25% glycerin and two counts were made on each sample.

The dilution was needed to increase viscosity thereby reducing the velocity movement of the droplets towards the surface.

The advantage of tha Galai Cis-1 system over the widely used Coulter Counter system is demonstrated by the fact that there Is no need for an electrolyte solution that can affect the stability of the emulsions. Both methods were needed since neither of them was able to measure accurately droplet sizes of the entire range of 100 to 3000nm. in most cases, the droplet size of the tested emulsions ranged from X00 to 400nm. However, when emulsions were subjected to accelerated stability tests, higher mean droplet size could have been in theory expected, and therefore.it was necessary fo measure diameters in the range of 0.6 to 2.0 pm. Thus, the droplet size distribution of emulsions which underwent stress conditions was analyzed using both the Galai Cis-1 and the Malvern systems. 3. Measurements of Zeta Potential The seta potential was measured using the moving boundary electrophoresis technique, which has been shown to yield accurate electrophoretic mobility data. Measurement of electrophoretic mobility and conversion of electrophoretic mobility data to seta potential, were performed similarly to that previously described (Benita et al., 1984, J.Pharm. Sci. 73: 1751-1755.). The electrolyte consisted of an aqueous solution containing 1% glycerol and 0.75% PLURDNIC® F-68 which helped to stabilize the moving boundary (preventing the free diffusion of the droplets due to osmotic pressure which occurs in normal aqueous media) without altering the electrophoretic mobility.

Each emulsion sample was diluted with 9 parts of water to 1 part of sample, prior to examination. In order to confirm the measurements reliability various commercial Intralipid (trade name manufactured by Kabi-VItrum) fat emulsions (which are emulsions used for nutrition, and comprise 10-20% soy oil, phospholipids and glycerin) were measured by this technique and were found to be identical, 1Q within th® limits of experimental error, to corresponding sets potential values published in the literature. Further confirmation of the reliability of this method came from the reproducibilityi of results.

C. pH Measurement The pH of the emulsion samples was measured using a pH me'csr (radiometer pH M63, Copenhagen, Denmark). e Example 1: Preparation of an emulsion containing diazepam A) - Oily, alcoholic and aqueous solutions were separately prepared as follows (all amounts below are given 2θ In % w/v in relation to the final total emulsion volume): I. Oily Solution: The oily solution consisted of the following ingredients: 1) 10% TCM (Societe Industrielle de Oleagineaux, St. Laurent, Slangy, France), and 10% purified soybean oil (Bertin, Courbevoie, France), which was refrigerated, for about a week to remove waxy substances. 2) 0.05% c~tocopherol (Sigma Chemicals, St. Louis, MO, U.S.A.). 3) 0.5% diazepam (Teva Pharmaceuticals Inc., Kfar Saba, Israel).

II. Alcoholic Solution Tha alcoholic solution consisted of the following ingredients: 1) 0.5% deoxycholic acid - D.C.A. (Sigma, St.

Louis, MO, U.S.A.). 2) 1.0% purified fractionated egg yolk phospholipids, prepared from crude egg yolk phospholipids (Sigma Chemicals, St. Louis, MO, O.S.A), In accordance with a modification of an earlier technigue reported by Schuberth and Wrethind (Acta. Chir. Scand. Suppl. 278: 1-21, 1961), as represented schematically In Fig. 1 of the annexed drawings. The purification generally consisted of four extraction cycles with petroleum ether 80 100 as extraction solvent. These purified phospholipids consisted mainly of phosphatidylcholine and phosphatidylethanolamine, together with small quantities of phosphatidylserine, phosphatidylinositol and phosphatidlc acids (verified by standard TLC procedure).

III. Aqueous Solution: The aqueous solution consisted of the following ingredients: 1) 2% poloxamer (PLURONIC® F-68, BASF, Ludwigshaf en, FRG) 2) 2.25% glycerin (Merck, Darmstadt, FRG). 3) 0.2% methyl paraben (methyl p-hydroxybenzoic ester; Sigma Chemicals, St. Louis, MO., U.S.A.) and 0.075% of butyl paraben (butyl p-hydroxybenzoic ester; Sigma). 4) Double distilled water (DDW) added up to 100%.

Ingredient (3) was not always present and was only added when no autoclaving was to be applied.

The alcohol solution was admixed. with the aqueous solutions and the alcohol was rawed by evaporation. The so obtained solution is the one which is hereinafter referred to as the aqueous solution.

Emulsion Preparation: The whole process for the preparation of the emulsion was conducted under nitrogen atmosphere and under aseptic conditions. This process is schematically represented in Fig. 2 of the annexed drawings.

Both solutions were appropriately filtered using 0.22 μη Millipore (trade name) membrane filter. After fitration, the aqueous and the oily solutions were heated separately to 70°C and dispersed by a magnetic stirrer. Further heating was applied while mixing until the temperature reached 85°C.

At this temperature, the two solutions were mixed and emulsified during 5 min. using a high shear mixer, [Polytron (trade name) Kinematica, Lucerne, Switzerland]. The resulting coarse emulsion was cooled rapidly below 20*C. A fine monodispersed emulsion (i.e. having a small range ox droplet sizes) was then achieved following 20 homogenization cycles, using a Wo-stage homogenising valve assembly (Gaulin homogenizer, APV Gaulin, Hilversum, The Netherlands), at a temperature of 40-70°C under pressure of about 8500 psi.

Following the homogenisation, the pH was adjusted to 8.0 using a 10% sodium hydroxide solution and the emulsion was filtered using a 1 pm filter, to discard the coarse droplets which were generated during the emulsification and homogenisation processes and also other debris.

Samples of the so filtered fine clean emulsion were stored in 10 ml brown ampoules and no phase separation was observed over periods of more than, fourteen months.

Example 2: Preparation of an. emulsion containing diazepam In a similar manner to that described In Example 1, diazepam containing emulsions were prepared, replacing, however, th® purified fractionated egg yolk phospholipids (ingredient 3 of the oily solution) with OVOTHIN 160 (Lucas Meyer, Hamburg, Germany).

Similarly as in Example 1, no phase separation was seen even after storage of more than twelve months.

Example 3: Stability of th® emulsions The stability of the emulsions of Examples 1 and 2 was determined by measuring various parameters of the emulsion at various time Intervals following their preparation. The emulsions were stored at 4eC. Essentially no change in pH, zeta potential, mean droplet size, droplet size distribution and drug content was observed for more than fourteen months after preparing the emulsions. The stability tests are still under evaluation.

Some batches of the above emulsions were pubjectec.,. following theix’ preparation, to a thermal shock by subjecting them fo autoclaving - l.latm., 121 °C, 15 min. Such a thermal shock is considered in the art as an effective accelerated test for assessing emulsion stability. However, surprisingly, even for such emulsions, no loss In stability was observed as determined by measuring the same above parameters. Similarly as above these emulsions retained their initial properties for more than four months after sterilization was performed.

Example 4 : Stability of emulsions prepared with either deoxycholic acid or sodium deaxycholate The emulsion of Example 2 was successively modified to give four different formulations as shown in the following Table I: TABLE 1 Ingredients Formulations Amount (%) 1 2 3 4 Soybean Oil - 10.0 - 10.0 MCT oil 20.0 10.0 20.0 10.0 c-tocopherol 0.02 + 4- 4 + OVOTHIN 160 1.0 4 4* 4- 4 Diazepam 0.5 + + 4- + PLURONIC^ F-68 2.0 4 4- 4- 4 SDC.* - 1.0 1.0 DCA.** 0.5 0.5 - - Glycerol .25 4 4- 4- 4 Water to 100 4 4- 4- 4 * SDC. - Sodium deoxycholate ** DCA. - Deoxycholic acid The zeta potential and the droplet size of the various formulations Is shown In the following Table IX: TABLE II Droplet size (nm) Formulation mean S.D.* Seta Potential. (-mv) 1 112 27.9 48 2 117 29.8 45 3 125 31.2 35 4 137 36.8 32 * S.D. - standard deviation It can be seen that the compositions comprising MCT oil as the sole oily carrier had improved properties as compared to those prepared with equal concentrations of both MCT and vegetable oil. Additionally, the results show that emulsions comprising DCA had smaller, more uniform droplets and greater seta potential than compositions comprising SDC. Hence the preference in utilizing DCA over SDC.

Example 5 ; Synergism between phospholipids, non-ionic surfactant and deoxycholic acid in diazepam containing emulsions The emulsion of Example 2 (without ©tocopherol) was successively modified to give emulsions of different formulations as shown In Table III below; TABLE III Ingredient Concentration FI F1I Fill FIV Ftf FVI FVII in % (w/v) Soybean, oil 10.0 + 4- 4- 4- 4- CT Oil 10.0 ·»· ·*· -j- 4- 4· 4- 4- Diazepam 0.5 + + 4- 4- 4- 4- 4- OVOTHIN 160 1.0 4- 4 - 4- - - PLURONIC® F-68 2.0 4- - 4· - + - Deoxycholic acid 0.5 + 7- 4· - - 4- Glycerin 2.25 + + 4- 4· 4· 4. + Distilled water to 100.0 4- 4· 4 4. -r 4 4» All formulations were prepared on the same day with the same reagents and using the same preparative procedure, as described in Example 1„ Following preparation the emulsions were sterilised by autoclaving (121° C, 1.1 atm, 15 min.).

The emulsions were first checked visually to determine the degree of creaming and those compositions that remained stable after 1 week were checked further to determine the droplet size and zeta potential.

The following results were obtained: Formulation FI; This emulsion, which was the one of Example 1, was the most stable one and it remained stable for over fourteen months, and no creaming and phase separation were observed.

Zeta potential of this emulsion was measured to be -45mv and the mean droplet diameter was measured to be about 117 nm.

Formulation FIX: Th® emulsion was unstable and 3-4 weeks after its preparation phase separation was observed. The phase separation was evident by the appearance of oil drops on the upper surface of the emulsion.

Formulation Fill: Phase separation was observed within one day after preparation of the emulsion.

Formulation FIV: Creaming was observed within a day of preparation of the emulsion. There was a smaller proportion of drops having a larger diameter, which caused creaming, which developed in the course of rime to a total phase separation.

Formulation FV: The emulsion was unstable and total phase separation was observed within 2 days.

Formulation FVIs Creaming was observed In the emulsion within a day of its preparation. The degree of creaming increased in the following days resulting finally in a complete phase separation.

Formulation VII The emulsion was very unstable and phase separation, was already observed In the course of its preparation.

SaHKAKg; The emulsion of Formulation FI is the only one containing all the ingredients. The many-fold Increase In stability over any of the emulsions of Formulations FIX to FVII is attributed to the synergistic action which the oils, phospholipids, non ionic surfacants and deoxycholic acid have on long term stability of the compos!ton.

Example 6 : The effect of a thermal shock on a diazepam containing emulsions The emulsions of Example 4 were subjected to a 20 thermal shock by sterilizing In an autoclave (15 min, 121°, 1.180 atm). The mean droplet size (M.D.S.) and the standard deviation (S.D.) were determined before and after autoclaving and tha results are given in the following Table IV: TABLE IV Formulation No. Before autoclaving After autoclaving M.D.S. S.D. M.D.S. S.D. 1 112 27.9 112 29.6 5 2 117 29.8 126 31.2 3 125 31.2 150 39.4 4 137 35.8 135 37.6 The above results show clearly that sterilization had very little effect on droplet size of the emulsions and this remarkable result is in contrast to the instability of hitherto known emulsions of the oil-in water type.

Example 7 : Stability to autoclaving ox a miconazole base containing emulsions In a similar manner to that described in Example 1 15 an emulsion comprising the following ingredients was prepared (% w/v): Miconazole base - 1.0; MCT oil - 20.0; OVOTHIN 160 1.0; c-Tocopherol ~ 0.02; PLOBCNIC F-68 - 2.0; DCA 0.5; Glycerol 2.25; and ftater to 100.

The droplet size and standard deviation, was measured before and after sterilization in an autoclave as in Example 6 and the results are shown in the following Table V: TABLE V Before autoclaving M.D.S. S.D. After autoclaving M.D.S. S.D. 135 45.9 141 30.0 Here again, the surprising stability of the emulsion to autoclaving is demonstrated.

Example 8: Preparation of an emulsion containing amphotericin B Amphotericin 3 was dissolved in methanol (0.8 10 mg/ml) by bath sonication (15 min). Phospholipids Ξ-80 (containing mainly 80% phosphatidylcholine and 8% phosphatidyl ethanolamine according to manufacturer specifications) were dissolved in chloroform. Both solutions were mixed and filtered through a combined filtering system comprising a fiber glass prefilter (GF.92, Schleicher and Schuell, FRG) and 0.45pm regenerated cellulose membrane filter (RC 5, Schleicher and Schuell, FRG), for removing pyrogens and aggregates. The resulting clear lipid solution was deposited as a thin film on the walls of a round-bottom flask by rotary evaporation under reduced pressure at 40eC. The aqueous phase comprising the poloxamer, sodium ceoxycholars and glycerin was filtered through a 0.22 pm Millipore (trade name, manufactured by Millipore, Bedford, Mass., U.S.A.) filter, poured into the flask and the dispersion was sonicated, until a homogeneous liposomal mixture was achieved.

MCT oil, filtered through 0.22 pm Millipore filter and containing c-tocopherol was heated to 70°C and then admixed Into the liposomal mixture heated to 45’C and dispersed therein by a magnetic stirrer. Emulsification was carried out while maintaining the same temperature using a high shear mixer, Polytron (Kinematics, Luzern, Switzerland). The resulting coarse emulsion was cooled rapidly. A fine mono-dispersed emulsion was achieved using a two stage homogenizer (APV Gaulin, Hilversum, The Netherlands).

Finally, the pH of the emulsion was adjusted to 8.0 with unbuffered 10% sodium hydroxide solution and the final emulsion was filtered through a 0.45 pm Millipore filter to discard coarse droplets and debris generated during the emulsification and, homogenization processes.

All the processing operations were carried out under aseptic conditions. The sterility of the emulsions was assessed using the Bactec 46 apparatus (Johnson Laboratories, Towson, MD)„ This instrument is used fo test inoculated Bactec culture vials for the presence of radioactive Carbon dioxide (W/ In the vials. Should a high level of “XO? be present in vials used for culturing aerobic or anaerobic organisms, it Indicates that there were viable microorganisms In the original inoculum. The negative results obtained using this technique showed that the emulsions were sterile.

The relative amounts of the various ingredients in the final emulsions were as follows: 0.075% amphotericin B, 20% MCT oil, 0.5% phospholipid E 80, 2.0% poloxamer, 1.0% sodium deoxycholate 2.25% glycerine, 0.02% ©-Tocopherol and bi-distilled wafer 200%.

For the purpose of various comparative tests to be reported below, also a plain emulsion, namely one which did not contain any lipophilic drug was prepared under Identical experimental conditions.

Example 9; Evaluation of the properties of an amphotericin B containing emulsion The emulsion of Example 8 was evaluated and found to have a mean droplet sise of about 100 nm as shown in Fig. 3. Furthermore, as may be seen in this Figure, no notable difference was found in tha droplet sise between the amphotericin and tha plain emulsion.

This is further shown in the following Table VI; TABLE VI EMULSIONS DROPLET SIZE ZETA POTENTIAL pH -------- (juv) MEAN S.D.(*) POLYD.(**) PLAIN 103 29.8 0.122 -35.3 8.0 WITH 97.5 23.8 0.130 -32.4 8.0 AMPHOTERICIN (*) S.D. - Standard deviation (**) Poly D - polydispersity, a factor reflecting the homogeneity of the population As may be seen from Table VI, the droplet sise of th® two emulsions were very homogeneous. Furthermore, there was also no notable difference in the seta potential between the two emulsions.

The amphotericin, emulsion of Example 8 was stored for a period of three months at 4 °C. After such a storage period, the seta potential, the pH as well as the particle sise distribution of both types of emulsion remained practically unchanged. Furthermore, the amount of amphotericin, · -determined by HPLC as known par se, did not change for up to three months storage at 4eC, indicating that the stability of amphotericin was not affected by its incorporation in the emulsion.

The amphotericin, emulsion was subjected to an accelerated shaking stability test, at a shaking rate of 100 strokes per minute at 25°C for forty eight hours. No droplets having diameter above 1pm were detected by the Galai Cis-l system while a slight and insignificant Increase in the droplet size of the emulsion was noted with the Malvern PCS method. These results indicate that the amphotericin emulsion remained stable in spite of the mechanical stress.

The droplet size distribution of amphotericin emulsion and plain emulsion after three months’ storage at 4’C is shown in Fig. 4. It may be seen that there is no difference between th® sis® distribution of the two emulsions and by comparing these results with those of Fig. 3, it may be seen that there is no substantial difference in the droplet sise distribution after storage.

Example 10: Animal studies with amphotericin formulations Thirty Balb/c mice (weighing about 20g) were injected through the tail vein with 5 x 10^ of Candida albicans, strain 562, in 0.1 ml of saline. This dose was shown to cause the death of all tha . infected mice within fiv® to ten days.

Forty eight hours after the infection was initiated each mouse received a post Infection treatment. The mice were divided into three groups of ten mice, each group receiving a different treatment. The treatment consisted of an injection of 0.1 ml into the tail vein of one of the following formulations: a) Fungizone which is a commercial amphotericin 3 formulation, (trade name manufactured by e.R. Squibb & Sons, Ltd!) at an amount of 0.4 mg/kg of amphotericin; proper dilution in order to achieve the aforementioned amount was achieved in accordance with manufacturers’ specification; - 26 fo) An emulsion of Example 8, at an amount of 0.4 mg/kg; dilution of the batch formulation in order to achieve the aforementioned amount was performed with a plain emulsion (see Example 8); c) Saline.

Th® number of surviving animals In each group was recorded daily, and the survival results are shown in Fig. 5.

It can be seen that all the untreated infected control animals died seven days after Candida albicans inoculation. All the infected mice which were treated with Fungizone died from infection 11-19 days after the Injection while a much prolonged survival rate was observed in the animals injected with the amphotericin emulsions in accordance with the invention, and 50 days after inoculation, 55% of the mice were alive and appeared in a good condition.

These results demonstrate the improved msdiccl properties of emulsions In accordance with the present invention.

Claims (28)

1. A pharmaceutical composition comprising an effective amount of a hydrophobic drug and a pharmaceutically acceptable carrier being an oil-in-water type emulsion comprising (i) about 3-50% (w/v) or an oily carrier consisting of medium chain triglyceride (MCT) oil, optionally in combination with vegetable oil; (ii) 0.05-20% (w-v) phospholipids; (iii) about 0.03-10% (w/v) of a non-ionic surfactant; and (iv) about 0.05-10% (w/v) of an ionic surfactant selected from bile-duct surrace active agent, cholic acid and deoxycholic acid and their surface active derivatives and salts.

2. . A composition according - to Claim 1 in a form suitable for parenteral administration.

3. A composition according to Claim 1 in a form suitable for topical administration.

4. . A composition according to Claim 1 in a form suitable for oral administration.

5. . A composition according to Claim 1 in a form suitable for ocular administration.

6. - A composition according to Claim 2 , in which the relative proportion of the non aqueous phase which comprises said oily carrier, phospholiplids, non-ionic surfactant and said ionic surfactant does not exceed 30%.

7. A composition according to Claim 6, in which the relative proportion of said non-aqueous phase does not exceed 25%.

8. A composition according to any on© of the preceding claims, wherein the relative proportions of the oily carrier is about 10-20%.

9. A composition according to any one of the preceding claims, wherein the relative proportions of the phospholipid is about 0.5-2%.

10. A composition according to Claim 9, wherein the relative proportion of the phospholipid is about 0.75%.

11. - A composition according to any one of the preceding claims wherein the relative proportions of the non-ionic surfactant is about 0.5-3%.

12. . A composition according to any one of the preceding claims wherein the relative proportions of the said non-ionic surfactant is about 3%-10%. tf

13. Acomposition according to Claim 1 2 , wherein the relative proportion of the said ionic surfactant is about 45.6%.

14. A composition according to any one of the preceding claims, wherein the vegetable oil is selected from soybean oil, cotton seed oil, olive oil and sesame oil.

15. A composition according to any one of the precedino claims, wherein the non ionic surfactant is a poloxamer.

16. A composition according to any one of the preceding claims, wherein the said ionic surfactant is selected from cholic acid, deoxycholic acid and their sodium salts.

17. A composition according to any one of the preceding claims wherein said drugs is selected from hydrophobic or lipophilic antibiotics or narcotic drugs, hydrophobic benzodiazepines, non-steroidal anti-inflammatory lipophilic drugs, lipophilic steroids, lipophilic azoles, lipophilic polypeptides, lipophilic sterols, lipophilic cephalosporines and dimarcaptol. )

18. 1 8 . A composition according to Claim 17, wherein said drug is selected from amphotericin B, morphine-base, diazepam, fluphenazine deconate, lorazepam, piroxicam, indomethacin, progesterone, testosterone propionate, miconazole, clotrimazole, cyclosporine, deoxycortone, calciferol, cephalosporine and dimercaptol. . \

19. » A composition according to Claim 1 8 , wherein said ί» drug is morphine.

20. A composition according to any one of the preceding claims wherein the mean oily droplet diameter is below 0.2pm.

21. A composition according to Claim 20,wherein the mean oily diameter droplet is about 0.1-0,15pm.

22. A process for the preparation of a composition of the oil-in-water type emulsion comprising an effective amount of a hydrophobic drug, about 3-50% (w/v) of an oily carrier consisting of MCT oil, optionally in combination with vegetable oil, about 0.05%-20% (w/v) of phospholipid, about 0.0310% (w/v) of a non-ionic surfactant, and about 0.05-10% (w/v) of an ionic surfactant selected. from bile-duct surface active agent, cholic acid and deoxy cholic acid, and their surface active derivatives and salts, which process comprises: (a) preparing a liposome mixture comprising the phospholipids, the non-ionic surfactant, the said ionic surfactant, and where the drug has a poor oil solubility, also said drug; (b) preparing an oily mixture comprising said oily carrier, and where the drug is lipophilic, also said drug; (c) mixing said liposome mixture with said oily mixture, whereby said emulsion is obtained. r

23. a process according to Claim 22, wherein the so obtained emulsion is subjected to further stages in which smaller droplets in the emulsion are obtained and/or the homogeneity of the droplets' size is increased. 5

24. A precess according to Claim ,22 or 23, wherein said drug has a poor oil solubility.

25. . A process according to Claim 24, wherein said drug is amphotericin B.

26. A pharmaceutical composition according to Claim 1, 10 substantially as hereinbefore described and exemplified.

27. A process for the preparation of a compositon of the oil-in-water type emulsion, substantially as hereinbefore described and exemplified.

28. A composition of the oil-in-water type emulsion, 15 whenever prepared by a process claimed in a preceding claim.