WO1995006463A1

WO1995006463A1 - Pharmaceutical compositions containing anionic surfactants

Info

Publication number: WO1995006463A1
Application number: PCT/IB1994/000251
Authority: WO
Inventors: William J. Curatolo; Michael J. Gumkowski; Julian B. Lo; Ward M. Smith
Original assignee: Pfizer Inc.
Priority date: 1993-09-01
Filing date: 1994-08-15
Publication date: 1995-03-09
Also published as: FI943998A0; FI943998A; AU7273494A

Abstract

Pharmaceutical compositions comprise an enzymatically labile pharmaceutically active agent or a prodrug which is permeable through the intestinal wall, and at least one anionic surfactant which is capable of protecting said active agent or prodrug against deactivation by enzymes. A method for the inhibition of the degradation of an enzymatically labile pharmaceutically active agent or prodrug by gastrointestinal enzymes comprises combining said agent or prodrug with an anionic surfactant.

Description

-I-

PHARMACEUTICAL COMPOSITIONS CONTAINING ANIONIC SURFACTANTS

This invention relates to pharmaceutical compositions containing anionic surfactants, to methods for the inhibition of the degradation of certain pharmaceutically active agents by combining them with anionic surfactants, and to methods of co- administering said active agents and said anionic surfactants. The co-administration of a non-permeable pharmaceutically active agent with a surfactant is mentioned in Swenson and Curatolo, Advanced Drug Delivery Reviews, 8, 39-92 (1992). The surfactant is described as enhancing the permeability of a non- permeable drug through the intestinal wall.

United States Patent No. 4,579,730 suggests that the anionic bile salt sodium cholate, which is a surfactant, functions as a protease inhibitor in the small intestines so promoting absorption of insulin. The general use of anionic surfactants as protease inhibitors in the gastrointestinal tract is not suggested.

The use of non-surfactant protease inhibitors as protectants against gastrointestinal proteases has been described in Lee, J. Controlled Release, 13(1990)213-223, Ziv et al, Biochem. Pharmacol., 36(1987)1035-1039, and U.S. Patent 4,579,730. Hayakawa et al, Life Sciences 45,167-174(1989), reports that the bile salt sodium glycocholate and the nonionic surfactant polyoxyethylene-9-lauryl ether either inhibit or stimulate degradation of insulin by nasal homogenates, depending on the concentration of the surfactants. European Patent Publication No. 332,222 indicates that the protease activity of vaginal washings is decreased in the presence of the anionic surfactant sodium dodecyl sulfate and also discloses a method of vaginal coadministration of an ionic or nonionic surfactant with a biologically active polypeptide to inhibit vaginal protease at the site of administration.

In accordance with the invention, pharmaceutical compositions for oral administration are provided comprising an enzymatically labile pharmaceutically active agent or a prodrug which is permeable through the intestinal wall and at least one anionic surfactant which is capable of protecting said active agent against deactivation by enzymes.

In one embodiment of the invention, the active agent is a peptide having a molecular weight of less than about 1 ,500. In other embodiments of the invention, the anionic surfactant is sodium lauryl sulfate, dioctyl sodium sulfosuccinate, a bile acid, a bile salt, a fatty acid or a salt of a fatty acid. In another embodiment of the invention, an oil is included in the composition. Examples of suitable oils are monoglycerides, e.g., mono-octanoin or monodecanoin, diglycerides, e.g., glyceryl-1 ,2-dioctanoate, and triglycerides, e.g., vegetable oil or caprylic/capric triglyceride. The invention also provides a pharmaceutical composition for oral administration comprising (1 ) an enzymatically labile pharmaceutically active agent or a prodrug which exerts its therapeutic activity locally in the stomach or intestine, and (2) at least one anionic surfactant which is capable of protecting said active agent against deactivation by enzymes. The invention further provides a method for inhibition of the enzymatic degradation of an enzymatically labile pharmaceutically active agent or a prodrug which is permeable through the intestinal wall by combining said active agent or prodrug with an anionic surfactant which is capable of protecting said active agent or prodrug against deactivation by enzymes. The invention also provides a method for the oral administration of an enzymatically labile pharmaceutically active agent or prodrug which is permeable through the intestinal wall to a host which comprises co-administering to said host said active agent or prodrug and at least one anionic surfactant capable of protecting said active agent or prodrug against deactivation by enzymes. The enzymatically labile pharmaceutically active agents of the invention contain enzymatically labile bonds, such as ester, amide and/or peptide bonds, and are inactivated by digestive enzymes in the gastrointestinal tract. Examples of such digestive enzymes are pepsin, trypsin, chymotrypsin, elastin, aminopeptidase, carboxypeptidase, lipase and intestinal glycosidases and esterases. The prodrugs according to the invention are compounds which become pharmaceutically active after oral intake. In other words, the prodrugs according to the invention are pharmaceutically active agents containing a prodrug group, such as an ester or amide group, which splits off in vivo after oral intake. The pharmaceutically active agent formed in vivo may or may not contain an enzymatically labile bond. The prodrugs are in any event themselves enzymatically labile by connection of the prodrug group to the pharmaceutically active compound through an enzymatically labile bond such as an ester or amide bond. Polar poorly permeable drugs may be rendered more permeable by conversion to more non-polar drugs, for instance by esterification of a carboxyl group. Prodrugs of this type can be labile to gastrointestinal enzymes.

Examples of enzymatically labile pharmaceutically active agents (the active agents) are calcitonin, prolactin, adrenocorticotropin, thyrotropin, growth hormone, gonadotropic hormone, parathyroid hormone, oxytocin, vasopressin, gastrin, tetragastrin, pentagastrin, glucagon, insulin, secretin, substance P, gonadotropin, leutinizing hormone releasing hormone, leuprolide, enkephalin, follicle stimulating hormone, cholecystokinin.thymopentin, endothelin, neurotensin, interferon, interieukins, insulinotropin, and therapeutic antibodies; and analogues of the above agents, which possess D-amino acids, blocked amino or carboxyl end groups e.g., nafarelin acetate and YdAGFdL (an enkephalin analogue), and non-natural amino acids such as S-methyl cysteine and statine. Also included are purified extracts of natural origin and their chemical modifications, as well as products obtained by tissue culture and products obtained by cultivating microorganisms or cells rendered productive by genetic engineering techniques. Also included are synthetic peptides and derivatized synthetic peptides such asterlakiren (isopropyl-N-[N-(4-morpholine-carbonyl)-L-phenylalanine-S- methyl-cysteine]-2(R)-hydroxy-3(S)-amino-4-cyclohexyIbutanoate) disclosed in U.S. Patent 4,814,342, Example 4 thereof, which is incorporated herein by reference.

The anionic surfactant of the invention is used in an amount which is effective in protecting the active agent against deactivation by enzymes.

Examples of suitable anionic surfactants are alkylsulfates such as sodium laurylsulfate (SLS); acyl sulfates such as dioctyl sodium sulfosuccinate (DOSS); salts of bile acids such as cholic acid, deoxycholic acid, glycocholic acid, taurocholic acid, glycodeoxycholic acid, taurodeoxycholic acid, ursocholic acid, ursodeoxycholic acid, chenodeoxycholicacid.glycocheno-deoxycholicacid. andtaurochenodeoxycholicacid; and fatty acids such as oleic acid.

In general, an active agent or prodrug is considered permeable through the intestinal wall if it can permeate the intestinal wall without the aid of a permeability enhancer. The intestinal permeability of the enzymatically labile active agent or prodrug is determined by perfusion of a solution of the active agent or prodrug through a segment of the intestine of an anesthetized rat. This test must be carried out in the absence of digestive enzymes to reduce enzymatic degradation of the tested active agent or prodrug. The intestinal segment therefore must be properly washed before the test or the test must be in the presence of inhibitors of digestive enzymes, such as Bowman-Birk trypsin/chymotrypsin inhibitor.

For the purposes of the invention, the enzymatically labile active agent or prodrug is considered permeable through the intestinal wall when it has a P_w greater than about 3.5 X 10^"β cm/sec. The P_w of a compound may be determined from the following equation:

wherein K_A is the absorption rate constant of the compound, A is the surface area of the intestinal segment, and V is the volume of the intestinal segment. When the intestinal segment is cylindrical and the intestinal radius is about 0.2 cm, as in the rat, A V is about 10 cm^'1.

The absorption rate constant K_A for a compound is calculated in the rat intestinal permeability test from the following equation:

wherein C_; is the concentration of the compound at the start of the test, C₀ is the concentration of the compound in the perfusate after passage through a 22 cm intestinal segment, Q is the flow rate and V is the volume of the intestinal segment, as mentioned above.

Terlakiren is an example of an enzymatically labile drug which has good intestinal permeability, and does not require a permeability enhancer to achieve significant oral absorption. Terlakiren has a K_A of 0.02 min \ a P.^ of 3.3 x 10^'5 cm/sec, and an aqueous solubility of 0.08 mg/ml.

Friedman and Amidon, Pharmaceutical Research, 8,93-96 (1990), assesses the permeability of the pentapeptides Leu-enkephalin and Leu-D(Ala)₂-enkephalin using the rat intestinal perfusion model. Analysis of the data in the reference using the above equations (1) and (2) results in a P_w value of 1.3 X 10^"3 cm/sec for both enkephalins. These compounds are thus permeable under the definition of permeability of the invention. These compounds are also enzymatically labile. An example of an enzymatically labile compound which is impermeable under the above definition of permeability according to the invention is insulin having a P,_pP of 4.97 X 10^"7 cm/sec. Examples of active agents which exert their therapeutic activity locally in the stomach or small intestine are anti-ulcer medications such as sucraffate, cholesterol lowering agents such as cholestyramine, hormones such as gastrin and cholecystokinin, antibiotics and other therapeutic agents. In general, the coadministration of anionic surfactants with an enzymatically labile pharmaceutically active agent or prodrug will protect the agent or prodrug from enzymatic hydrolysis when the surfactant and the agent or prodrug are coadministered orally, rectally, nasally, or vaginally.

The anionic surfactants according to the invention which are capable of protecting the active agent against deactivation by enzymes may be identified by the in vivo test described in Example 1 or an in vitro enzyme inhibition assay as described in Example 2.

An oil may be coadministered with the active agent and the protective anionic surfactant. In the context of the invention, an oil is a liquid which is immiscible with water. The oil may aid in solubilization of the active agent where the active agent is non-polar. In some cases, the oil may also be a protective nonionic surfactant, for instance Capmul-MCM (monooctanoin). Other suitable oils include triglycerides, diglycerides, and monoglycerides.

Suitable combinations of anionic surfactant and oil include SLS or DOSS with Miglyol-812 or Capmul-MCM. Mixtures of more than two anionic surfactants and oils are possible. For example, SLS and DOSS may be combined with Miglyol-812.

Suitable oils for use in this invention are:

I Example Chemical Description |

I Miglyol 812 Octanoic/Decanoic triglyceride j Soybean oil Vegetable oil

Sesame oil Vegetable oil

Olive oil Vegetable oil

Oleic acid Fatty acid lmwitor-308 Mono-octanoin

Imwitor 742; Capmul-MCM Mono/di-glyceride of octanoic and decanoic acids

Lipiodol lodinated vegetable oil

Capmul-GMO Glycerol mono-oleate

In a typical embodiment of the invention, a soft gelatin capsule contains 50 mg of the active agent, 640 mg oil (Capmul-MCM), and 160 mg surfactant (SLS or DOSS). In another typical embodiment, a hard gelatin capsule contains 50 mg of the active agent and 200 mg surfactant (SLS or DOSS). The quantity of surfactant or surfactant plus oil in a dosage form of this invention can vary widely. However, a single unit dosage form will contain from about 1 mg to about 500 mg of the active agent or prodrug, and from about 25 mg to about 1000 mg surfactant or surfactant plus oil.

The following Examples illustrate the invention.

EXAMPLE 1

Two capsule doses of a formulation of 50 mg terlakiren suspended in 15 mg DOSS mixed with 305 mg Miglyol 812, a triglyceride, were administered to four dogs. Each dog so received 100 mg of terlakiren and 30 mg of DOSS.

Table I gives the content of the formulation, and that of a control powder-filled capsule formulation (Powder), in mg.

Table II presents the mean AUC and the mean fold-improvement of the formulation over the Powder, and shows that the administration of 100 mg terlakiren with 30 mg of DOSS improved the bioavailability of terlakiren. The AUC is the area under the curve formed on plotting the drug concentration in plasma against the time elapsed after administration of the drug. Table

ExciDient Formulation Powder

Teriakiren 50 100

Miglyol 812 305

DOSS 15

Lactose - 80

Croscarmellose Sodium - 12

Sodium lauryl sulfate - 2

Magnesium stearate - 6 capsule size #0 #2 gelation shell hard hard

Table II.

mean AUC Mean Fold-

No. of dogs meg hr ml ¹ Improvement

Formulation 4 0.226 5.4 Powder 4 0.052 1.0

EXAMPLE 2 A standard procedure was employed to assess the in vitro potency of anionic surfactants vs chymotrypsin degradation of terlakiren. Terlakiren was dissolved in acetonitrile and added to a solution or dispersion of anionic surfactants (at concentrations of 0.04%, 0.2%, or 1%, gm/100 ml) in an isotonic citrate-phosphate buffer having a pH of 6.5. The drug (0.065 mM) concentration was assayed. Chymotrypsin was then added to start the reaction. The solution was placed into 37°C water bath and sampled at 5, 10, 15, 20, 25, 30, 35, 40, and 45 minutes. The reaction was quenched using a mobile phase having a pH of 2.5. The samples were then assayed by reverse phase high performance liquid chromatography (HPLC) of teriakiren using a Zorbax C8 column. The mobile phase was a 0.05 M monobasic potassium phosphate buffer: acetonitrile (50:50) mixture that was brought to pH 2.5 using phosphoric acid. The results in Table III demonstrate that the anionic surfactants reduce the chymotrypsin-catalyzed degradation of teriakiren.

Table III.

% Teriakiren

Chymotrypsin Remaining

Inhibitor/Control tøM) t = 30 min

Control 0.25 28

0.04% DOSS 0.25 78

0.2% DOSS 0.25 89

Control 2.5 0

0.04% DOSS 2.5 26

0.2% DOSS 2.5 69

Control 0.25 33

0.2% SLS 0.25 100

1.0% SLS 0.25 100

Control 2.5 0

0.04% SLS 2.5 93

0.2% SLS 2.5 97

EXAMPLE 3

The in vitro trypsin inhibition by surfactants was assessed with benzoyl-arginine- para-nitroanilide (BAPNA) as the enzymatically labile active agent or prodrug. Test solutions of trypsin at 1.25/ g/ml (103 benzoyi arginine ethyl ester units/ml), 0.5 mg/ml BAPNA, and 0.5 mg/ml SLS and DOSS surfactant were prepared in a buffer of 0.048 M TRIS and 0.019 M calcium chloride having a pH of 8 and containing 3.75 //g/ml bovine serum albumin. These test solutions were incubated at 37°C.

Samples were taken after 5 minutes and then at 5 minute intervals to 40 minutes, quenched with an equal volume of 30% by volume acetic acid, and filtered before analysis. The decay product of BAPNA hydrolysis, 4-nitroaniline, was analyzed with a Perkin-Elmer Lamba 3B UV-Vis spectrophotometer. The absorbance (A) of the quenched samples was measured at 410 nm. The ΔA/Δmin. in Table IV is determined from the initial slope of the curve obtained from plotting absorbance versus time.

The percentage inhibition of BAPNA degradation was calculated based on a comparison with a control which did not contain a surfactant, as follows:

% inhibition = 100% x [1 - (S/S₀)] wherein S, is the rate of change of absorbance with time in the presence of a surfactant, and S_c is the rate of change of absorbance with time in the absence of surfactant.

The results in Table IV demonstrate that the tested surfactants reduced the trypsin-catalyzed degradation of BAPNA.

Table IV.

Rate x lO³ Initial Rate Ratio

Composition ΔA/Δmin. (Surfactant/Control) % Inhibition

Control 7.76

SLS 0.2% 0.003 0.0004 100

SLS 1% 0.002 0.0003 100

Control 7.76

DOSS 0.2% 0.247 0.032 97

DOSS 1% 0.045 0.006 99

EXAMPLE 4

A formulation of terlakiren dissolved in an aqueous solution of SLS was administered to 12 dogs. Each dog received 100 mg of terlakiren and 180 mg of SLS.

Table V gives the content of the formulation and that of a control powder-filled capsule formulation (Powder) in mg.

Table VI presents the mean AUC for each formulation and the mean fold- improvement over the powder-filled capsule, showing that administration of terlakiren in a formulation that contained 180 mg of SLS improved the bioavailability of terlakiren. Table V.

Component Solution Powder

Terlakiren 100 100

Lactose - 80

Croscarmellose Sodium - 12

Sodium lauryl sulfate 180 2

Magnesium stearate - 6 capsule shell - #2 water* 150" a. The total amount of water administered with each dose was 150 ml. b. In ml

Table VI.

mean AUC Mean Fold- no. of dogs meg hr ml^"1 Improvement

SLS Solution 12 0.658 27.7 Powder 12 0.086 1.0

EXAMPLE 5

The in vitro potency of sodium oleate in the chymotrypsin degradation of terlakiren was assessed. Teriakiren was dissolved in acetonitrile and added to a solution or dispersion of sodium oleate (at concentrations of 0.1 , 0.2, 0.3, 0.4, and 0.5 mM) in a pH 6.5 isotonic phosphate buffer. Chymotrypsin was then added to start the reaction. The solution was placed into a 37° C water bath and sampled at 5, 10, 15, 20, 25 and 30 minutes. The reaction was quenched using a mobile phase having a pH of 2.5. The samples were then assayed by reverse phase high performance liquid chromatography of terlakiren using a Beckman Uitrasphere 5 micron 25 cm column. The mobile phase was a 0.05 M monobasic potassium phosphate buffeπacetonitrile (55:45) mixture that was brought to pH 2.5 using phosphoric acid.

The results in Table VII demonstrate that sodium oleate reduced the chymotrypsin-catalyzed degradation of terlakiren. Table VII.

% Terlakiren

Chymotrypsin Remaining Initial Rate

Inhibitor/Control tøM) t = 30 min (meg ml^"1 min^"1)

Control 0.1 58 0.46

0.1 mM Sodium Oleate 0.1 62 0.53

0.2 mM Sodium Oleate 0.1 76 0.37

0.3 mM Sodium Oleate 0.1 86 0.39

0.4 mM Sodium Oleate 0.1 85 0.19

0.5 mM Sodium Oleate 0.1 85 0.03

EXAMPLE 6

Benzoyltyrosine ethyl ester (BTEE) is an ester that is sensitive to hydrolysis in the presence of chymotrypsin. BTEE was dissolved in 100 μl of methanol and added to 10.9 ml of a solution or dispersion of anionic surfactant at concentrations ranging from 0 to 1.5%, in a pH 6.5 isotonic citrate-phosphate buffer. A one ml sample was removed to determine the starting concentration of BTEE, which was approximately 0.5 mM. A 100 //I solution of chymotrypsin in 0.001 N hydrogen chloride was then added to start the reaction. The final concentration of chymotrypsin in the reaction vial was 0.025 μM. The solution was stirred at 37°C, and sampled at ten minutes. The reaction was quenched by adding the HPLC mobile phase solvent. Samples were assayed by HPLC. Reactions were run in triplicate. As shown in Table VIII, in solutions that contained 0.025 μM chymotrypsin, nearly no BTEE remained after 10 minutes. The slurry of 6 mg/ml sodium ursodeoxycholate contained less than 0.6 mg/ml (1.5mM) of sodium ursodeoxycholate in solution. S.D. is standard deviation.

Table VIII.

Anionic Surfactant % of BTEE remaining after 10 minutes (S.D.)

Control 0.6 (0.4) 30 mM sodium glycocholate 17.1 (0.5)

6 mg/ml sodium 80.3 (1.5) ursodeoxycholate CLAIMS

1. A pharmaceutical composition for oral administration comprising an enzymatically labile pharmaceutically active agent or a prodrug which is permeable through the intestinal wall and at least one anionic surfactant which is capable of protecting said active agent or prodrug against deactivation by enzymes.

2. A composition according to claim 1 wherein the active agent is a peptide having a molecular weight of less than about 1 ,500.

3. A composition according to claim 1 or 2 wherein said composition comprises a prodrug. 4. A composition according to claim 3 wherein said prodrug is a derivative of a pharmaceutically active agent which does not contain peptide bonds.

5. A composition according to any one of claims 1 to 4 wherein said anionic surfactant is sodium lauryl sulfate, dioctyl sodium sulfosuccinate, a bile acid, bile salt, a fatty acid or a salt of a fatty acid. 6. A composition according to any one of claims 1 to 5 wherein an oil is included.

7. A composition according to claim 6 wherein said oil is a monoglyeeride, a diglyceride, or a triglyceride.

8. A composition according to claim 7 wherein said triglyceride is a vegetable oil or caprylic/capric triglyceride, said monoglyeeride is mono-oetanoin or monodecanoin, and said diglyceride is glyceryl-1 ,2-dioctanoate.

9. A composition according to any one of claims 1 to 8 wherein said enzymatically labile pharmaceutically active agent is terlakiren.

10. A method for the inhibition of the degradation of an enzymatically labile pharmaceutically active agent which is permeable through the intestinal wall which comprises combining said active agent with an anionic surfactant which is capable of protecting said active agent against deactivation by enzymes.

11. A method according to claim 10 wherein said active agent is a peptide with a molecular weight of less than about 1 ,500. 12. A method for the oral administration of an enzymatically labile pharmaceutically active agent which is permeable through the intestinal wall to a host which comprises co-administering to said host said active agent and at least one

Claims

anionic surfactant capable of protecting said active agent against deactivation by enzymes.

13. A pharmaceutical composition for oral administration comprising an enzymatically labile pharmaceutically active agent which exerts its therapeutic activity locally in the stomach or intestine, and at least one anionic surfactant which is capable of protecting said active agent against deactivation by enzymes.