IE850686L - Etoposide oral dosage form - Google Patents

Abstract

A liquid dosage form suitable for oral administration of etoposide which is sufficiently concentrated to be administered in capsule form and which provides improved absorption of the drug relative to prior oral formulations, comprises etoposide, polyethylene glycol, taurocholic acid, ethanol and a water-soluble acid. [GB2155789A]

Description

8 3 4 0 2 . The present invention refers to a drug bio effecting and body treating composition having a glycosidic active ingredient- Etcposide is a semi-synthetic product derived from podophyliotoxin. The material is identified by the chemical name 4 ' "demethylepipodophyllotoxin-S- (4,, 6-0IR) -ethylidene-bet&~j>~gluc~ opyranoside). It is referred to in the literature as vp-16-213, R VePesid , Bthylidene-Lignan Pr and EPEG. It has been evaluated for use in treatment of cancer under the auspicious of The National Cancer Institute under the number NSC-131540. It has recently been approved by the federal Food and Drug Administration for use in the treatment of refractory testicular cancer and has been proposed for use in the treatment of small cell lung cancer.

. In invescigat ions conducted under the auspicious of the National Cancer Institute, the drug was supplied as a solution for injection having the following compositions- etoposide, 100 mg; citric acid, anhydrous 10 mg; benzyl alcohol,. ISO »g? polysorbate 8Q4, purified, 400 mg; polyethylene glycol 300, 3.25 g; alcohol, absolute qs 5.12 g. Each ampule of the foregoing composition consisted of 5 ml of solution which was diluted 20 to 3 50 times with 0.9% sodium chloride or 5% dextrose for injection before e dm in is tr a t i. on by slow intravenous infusion.

When the foregoing intravenous composition was administered by ingestion rather than injection? the 5 ml ampoule was either 5 taken as a teaspoon dose form or•first diluted with water? it was found that the bioavailability by the oral route was approximately 90% that by the intravenous route (M.D8Jncalci et al., Cancer Chemoterapv and Pharmacology (1982) 7:141-145). A similar dose taken by capsule in which 100 mg of active 10 ingredient was contained in approximately 1.3 ml of encapsulated solution in which the vehicle consisted of polyethylene glycol 400, glycerine, water, and citric acid yielded only about one-half the bioavailability of the intravenous solution when taken by ingestion (M.D'Incalci et al., loc. cit.). The present 15 invention addresses this problem of reduced bioavailability of the capsule dosage form, and provides a liquid formulation of sufficiently high concentration for encapsulation which affords bioavailability upon ingestion equal to the intravenous solution.

The present invention takes advantage of our discovery that 20 taurocholic acid when included in a solution dosage composition with etoposide results in markedly improved absorption of the drug following ingestion of the composition. It is belived that this is due to the formation of a micellar solution of etoposide on dilution thereof with the gastric contents. 25 In investigating this problem, we have found that the capsule formulation referred to above when mixed with water in the proportion of about 10 ml of water per 100 mg of etoposide results in the immediate formation of a heavy, milky white precipitate. When as little as an equal weight of taurocholic 4 acid relative to the etoposide is included in the liquid capsule formulation, precipitate formation is delayed for over an hour on mixing the formulation with 10 ml of water. The following tabulation illustrates this effect of taurocholic acid and other 5 bile acids.

EFFECT OF ADDED BILE ON PRECIPITATE FORMATION Experiment No, 8 i 1 e Ac i d or . Salt- Amount of * Etoposide (mg) Amount of BiJe Acid/ Salt (mg) Precipitate Formation Time (hr} Solution pH 10 15 1 2 3 4 5 6 7 S 9 10 11 12 13 Taurocholic Acid Sodium Chelate Sodium Deoxycholate 200 200 100 100 100 100 100 200 200 100 100 200 200 1000 1.5 500 1,0 1000 21,0 500 5=0 200 2,0 100 1,5 10 Instantaneous 1000 500 10 00 500 1000 500 >24 1,0 >24 1L° >24 >24 4,7 10. 9 vt 11,0 '^'Supplied as a solution having the following composition; 20 etoposide, micconized polyethylene glycol 400 glycerol water citric acid 100,0 mg, 1084,0 mg. 81.5 mg. 77.6 mg, 2.0 mg.

Surface tension measurements on the aqueous dilutions of the bile acid formulations referred to in the foregoing table have confirmed that, indeed t. mi cellar solutions of etoposide are produced- This is reflected in the failure for a further decrease in surface tension to occur as the concentration of taurocholic acid in the solution is increased. That concentration where no further decrease in surface tension occurs is referred to as critical mi cellar concentration.

The phenomenon of micellar solubilization of poorly water-soluble drugs mediated by bile acids,, including taurocholic acid, has been previously reported with respect to griseofulvin, hexesterol, glutethimide (Bates et al., Journal of Pharmaceutical Sciences, 55, 191-199), reserpine, Malone et al., ibid. 55, 972-974 (1966) fatty acids, and cholesterol (Westergaard et al., Journal of Clinical Investigation, _58, 97-108 (1976))i According to the invention, there is provided an oral pharmaceutical composition in the form of a homogeneous liquid comprising etoposide, polyethylene glycol, taurocholic acid, ethanol, and a water soluble acid.

The pharmaceutical solution of etoposide of the present invention has the unique property of providing a stable apparent solution of the drug upon dilution thereof with from 1 to 100 volumes of water. The solution is stable and free of precipitate for a period of at least two hours sufficient to permit administration to and absorption by the mammalian organism. It has been found that the bioavailability of etoposide following oral administration of the present dosage form is substantially equivalent to that achieved by intravenous administration of a solution of a drug. It is believed that ingestion of the present dosage form and resulting dilution thereof by the stomach contents results in the formation of a micellar solution of etoposide in the stomach which is readily absorbed by the gastrointestinal tract. Applicants do not wish to be bound? however, by any theoretical explanation of the mechanism by which the superior oral bioavailability of the present formulation is achieved.

Polyethylene glycol having a molecular weight of from 200 to 400 is preferred as the vehicle for the present composition. Polyethylene glycol has the necessary solvent capability for etoposide and exhibits acceptable viscosity and dispersibility in water to meet the requirements of the present invention. Polyethylene glycol having molecular weight of from 200 to 300 is more preferred because it is less viscous than polyethylene glycol 40 0. The lower viscosity facilitates manufacturing manipulations, and increases the dispersibility of the'composition on mixing with water or gastric contents. Other ingredients of the composition serve to improve dispersibility and to facilitate micelle formation on mixing thereof with water f. or to improve compatibility of the solution with the oapsule shell when the 8 material is encapsulated in a soft gelatin capsule according to a preferred embodiment of the invention.

From 5 to 9 parts by weight of polyethylene glycol 300 per part by weight of etoposide is preferably employed. Within this 5 range the rate of solution of the etoposide is sufficient for manufacturing convenience, a sufficiently fluid mixture is obtained for convenient handling,,, and the solution is sufficiently concentrated so that a unit dosage form may be contained in a sufficiently small volume of solution to permit encapsulation 10 within a soft gelatin capsule. More dilute solutions may, of course, be prepared for dropper or teaspoon dosage use. Such is also contemplated by the present invention.

The etoposide is preferably micronized prior to formulation into the present composition, but this is primarily a convenience 15 and not a necessity since a true solution of etoposicfe in the polyethylene glycol is formed. Ordinarily when etoposide is dissolved in a water soluble organic solvent,, and the resulting solution mixed with water,, the etoposide precipitates because of its very low water solubility. According to the present invention, 20 taurocholic acid is included in the composition and the presence of this ingredient results*, presumably,, in the formation of a mice liar solution when the composition is mixed with water.

Other bile acids will similarly promote the formation of apparent micellar solutions on mixing of the polyethylene glycol 25 solution with water, but they are unsuited for use in the present compositions since the so-produced micellar solutions are unstable or do not form at acid pH. Sodium deoxycholate or sodium cholate form micellar solutions with etoposide, but the micellar solutions have pH values of pH 10.9 and pB 11.0 respectively. Upon acidifi-30 cation, the etoposide precipitates from such solutions. Such are not therefor suitable for ingestion due to the acidic nature or the gastric contents. Furthermore, for encapsulation within a soft gelatin capsule shell an acidic pH is preferred because the gelatin shell is disrupted by fill-solutions having pH values in excess of pH 8.0. It has been found by empirics! experimentation that preferably about 3.5 parts by weight of taurocholic acid per part by weight of etoposide are desirable to provide a stable micellar solution on dilution of the composition with water. Smaller amounts such as 2.0 parts* by weight, and larger amounts of taurocholic acid may be employed. No useful purpose is served by using more than about 10 parts by weight of taurocholic acid per part by weight of etoposide,, A water soluble acid is included in the composition to assure that an acidic pH value is obtained upon dilution to form the micellar solution. For purposes of pharmaceutical elegance and ease of handling in a manufacturing operation, we prefer to use a solid water-soluble organic carboxylic acid? but other acids may be employed„ We prefer maleictartaric,, citric{, gluconic,, or ascorbic acids which are water-soluble£, non-toxic and convenient to handle in a pharmaceutical manufacturing operation. Most ©referred is citric acid which we have found to be appropriate when used in from 0.1 to 0.5 parts by weight per part by weight of etoposide. The most preferred proportion is 0»2 parts by weight of citric acid per part by weight of etoposide Ethanol serves the important purpose in the composition of promoting rapid dispersion on mixing with water and facilitates formation of the micellar solution. Other water-soluble polar organic solvents such as methanol, propanoic acetone, etc. which are also effective are not suitable for ingestion and, accordingly ethanol has been selected for this purpose. At least 5% by weight of the composition of ethanol is necessary for this purpose, but higher amounts up to 20% by weight may be usedP particularly for purposes of a dropper or teaspoon dosage rorm.

For encapsulation within a soft gelatin capsule,, a maximum of 10% by weight of ethanol in the composition may be used. Solutions having higher concentrations of ethanol than 10% by weight may cause dehydration of the gelatin capsule wall and hence may not be suitable for encapsulation with this type of a capsule.

Finally£. for use of the present composition in a unit dose form contained within a soft gelatin capsule it is desirable to include up to about one part by weight of water per part by weight of etoposide to improve the compatibility of the composition with the soft gelatin capsule shell. The hydrophilic nature of polyethyleneglycol, ethanolt citric acid, and taurocholic acid causes the composition to abstract the water from the capsule shell and may cause it rupture on prolonged storage. Sufficient water is therefore included in the composition, preferably one part by weight of water per part by weight of etoposide,, to render the composition compatible with the capsule shell and prevent dehydration thereof. It is desirable to select an amount of water which will confer stability for a storage period of two years at room temperature when the capsules are stored in a closed container.

The preferred embodiments of the present invention are stable, liquid compositions in the forsn of true solutions having the following composition: 1 I Ingredient Parts by Weight polyethanol glycol 300 etoposide citric acid taurocholic acid ethanol 5 to 9 1 0-1 to 0.5 2.0 to 10 5 to 20% by weight of total solution weight The most preferred embodiment of the present invention is the following composition: 10 Ingredient Parts by Weight polyethylene glycol 300 6.8 etoposidej. micronized 1.0 citric acid - 0.2 ethanol 1.0 taurocholic acid 3.5 water 1.0 The following example constitutes a description of the preferred composition of the present invention.

Example 2o The following ingredients were weighed: Etoposide 25.Og Citric Acid, Anhydrous,. DSP 51 Og Polyethylene glycol 300 170.Og Alcohol, USP 25.Og 25 Taurocholic Acid 87.5g Purified Water, USP 25.Og The taurocholic acid is added portionwise to the polyethylene glycol 300 with stirring to form a suspension. The water is then added followed by the alcohol and citric acid. A solution forms which is warmed to 65°C, allowed to cool to 35°C, and filtered (Millipore AP 25 29325). An atmosphere of nitrogen is maintained over the solution during those steps. The filtrate is kept at 30-35°C, and the etoposide is then dissolved therein. The solution is then assayed (found 71.3 mg/g of etoposide) and filled into soft gelatin capsules at 100 mg etoposide per capsule.

•The foregoing capsule-fill solution has the following character is tics j, and stability.

CHARACTERISTICS 1. Color 2. pH 3. viscosity 4. Dispersibility 5. Shell Compatibility!. Physical 6. Precipitation formation Dark Brown 4.6 Satisfactory Easily dispersible Compatible time on dilution with H^O to >3 hours 1:1, 1:5, 1:10 and 1:100 I 3 STABILITY Storage Temperature Storage Time % Remaining {Bays) 4°C (Control) 8 100 70 °C 5 102 7 0 °C 8 102 56 °C 8 102 37 °C 8 105 25°C 8 59 -14-

Claims (17)

1. An oral pharmaceutical composition in the form of a homogeneous liquid comprising etoposide, polyethylene glycol, taurocholic acid, ethanol, and a water soluble acid.

2. The composition of Claim 1 in the form of a dosage unit containing from 10 mg to 100 mg of etoposide.

3. The composition of claim 1 or 2 in dosage unit form wherein said homogeneous liquid is contained within a soft gelatin capsule.

4. The composition of claim 3 wherein said homogeneous liquid also contains water in an amount sufficient to prevent dehydration of the capsule shell and to render said shell stable during a storage period of at least 2 years at room temperature in a closed container.

5. The composition of any of claims 1 to 4 wherein the molecular weight of the polyethylene glycol is within the range of about 200 to 400.

6. The composition of claim 5 wherein the molecular weight of the polyethylene glycol is about 300.

7. The composition of any of claims 1 to 6 wherein the weight of polyethylene glycol is from 5 to 9 times the weight of etoposide. - 15 -

8. „ The composition of any of claims 1 to 7 wherein said water soluble acid is a non-toxic organic carboxylic acid.

9. The composition of any of claims 1 to 7 wherein 5 said water soluble acid is citric acid.

10. The composition of amy of claims 1 to 9 wherein from 20 to 10 parts by weight of taurocholic acid per part by weight of etoposide is employed.

11. The composition of claim 10 wherein about 3.5 10 parts by weight of taurocholic acid per part by weight of etoposide is employed.

12. The composition of any of claims 1 to 11 wherein the amount of ethanol is from 5 to 20% by weight.

13. A liquid pharmaceutical dosage form comprising a 15 solution of the following composition: Ingredient Parts by V^eight polyethylene glycol 300 5 to 9 etoposide 1 citric acid 0.1 to 0.5 20 taurocholic acid 2.0 to 10 ethanol 5 to 20% by weight of the composition 25

14. The composition of claim 13 comprising a solution adapted for encapsulation within a soft gelatin shell and having the following composition: - 16 - Inaredi ent Parts by Weiqht polyethylene glycol 300 etoposide, micronized citric acid ethenol taurocholic acid wet er a. H 1.0 0.2 1.0 3.5 1.0

15. A composition as claimed in claim 1, the ingredients of which are substantially as set forth in the foregoing Example.

16. A method for the production of dosage forms as claimed in claim 13, substantially as described in the foregoing Example.

17. A dosage form produced by the method of claim 16. F. R. KELLY & CO. , AGENTS FOR THE APPLICANTS.