IE41461B1

IE41461B1 - Pharmaceutical formulations

Info

Publication number: IE41461B1
Application number: IE1865/75A
Authority: IE
Original assignee: Beecham Group Ltd
Priority date: 1974-09-21
Filing date: 1975-08-26
Publication date: 1980-01-02
Also published as: SE426909B; JPS5745413B2; NL7511059A; DK421075A; NZ178490A; FR2285146A1; AU8506875A; SE7510365L; DK143887B; JPS5161619A; BE833432A; DK143887C; DE2541881C2; NL185060C; CA1062614A; FR2285146B1; ZA755515B; IE41461L; GB1512378A; NL185060B

Abstract

1512378 Fluid pharmaceutical composition BEECHAM GROUP Ltd 16 Sept 1975 [21 Sept 1974] 41231/74 Heading A5 A fluid pharmaceutical composition comprises a medicament, an edible oil and a natural or synthetic clay which has been rendered more easily dispersible in edible oil by replacement of inorganic cations by organic cations. The composition may be used to treat neonatal scour in piglets. The medicament may be a penicillin.

Description

This invention relates to pharmaceutical formulations and. in particular to oil-based formulations for oral administration of medicaments to domestic animals.

For the administration of insoluble medicaments to animals by the oral route, the medicament is often presented as a suspension. In preparing such a suspension, it is generally desirable that the formulation base is of such a viscosity that the suspended material does not readily sediment out. For reasons zv of stability, ready-to-use anitbiotic suspensions are customarily prepared in an oily base. In order to produce an oily base which is sufficiently gel-like, the oil is heated in the presence of a suitable thickening agent, typically aluminium stearate. Such a process is lengthy and involved and therefore expensive. In addition, the rheological characteristics of the final gel are markedly influenced by slight variations inthe time/temperature conditions obtained during manufacture.

It is therefore an object of the present invention to provide an oil-based formulation whioh is simple and economical to prepare commercially, shows minimum batch to batch variation, and is sufficiently- gel-like to be suitable as a base for the incorporation of medicaments, and their oral administration to animals.

Accordingly, the present invention provides a fluid pharmaceutical formulation for oral administration to domestic animals which formulation comprises a medicament, an edible oil and an oleophilic clay, as hereinafter defined.

By the term oleophilic clay used herein is meant a natural or synthetic clay which has been rendered more easily dispersable in edible oil. by replacement of Inorganic cations therein by organic cations.

IS Suitable organic cations include ammonium ions substituted by at least one ^-,2-18 alkyl group.

Examples of such cations include cations of the formula (I) : R2 RX A© (I) / I R3 R4 2θ where R^ is a (-42.-18 alhyl. group, l<2 is ci liter a second alkyl, group, a benzyl group, a alkyl group or hydrogen, and and R^ are each a C, alkyl group or hydrogen. Examples of suitable cations within formula (I) include octadecyl ammon2j ium, dimethyl mono- and di-octadecyl ammonium, dimethyl hexadecyl ammonium, and dimethyl benzyl octadecyl ammonium ions. Preferably in formula (i) is a c1j_1g alkyl group, R2 is a c1^_1g alkyl group or a benzyl, methyl or ethyl group or hydrogen, and Rj and R^ are each a methyl or ethyl group or hydrogen.

Suitable clays for this ion-exchange treatment and subsequent use in the invention are usually those characterised by a high cation exchange capacity and high surface area.

Examples of oleophilic clays include those clays sold commercially as Bentones (Registered Trade Mark) (modified Bentonite, Berk Ltd.) and Attagels (modified Attapulgite, Engelhard). The Bentones are montmorillonites in which inorganic cations have been replaced by alkyl ammonium cations as described above, nor15 mally octadecyl ammonium, dimethyl mono- or di-octadecyl ammonium, dimethyl hexadecyl or dimethyl benzyl octadecyl ammonium ions, or similarly substituted hectorites. The Attagels are similarly substituted hydrated magnesium aluminium silicates belonging to the montmorillonite group of clays, but having a higher magnesium content than normal montmorillonites and containing traces of calcium and iron.

Oleophilic clays have been reported as additives for ointment bases (Billups and Seger, Am. J. Pharm., 1964, 136, 183-205) but such topical formulations are not fluid as required for ready oral administration to domestic animals. There is no suggestion in that publication of fluid oil-based formulations containing the modified clays, or of their advantageous properties.

The edible oil employed in the formulations of this invention should not be liable to substantial drying or oxidation. Preferably a vegetable oil is employed and suitable examples include sunflower oil, arachis oil, soya-bean oil, rapeseed oil, and maize oil.

The present formulations are of value for any type of medicament and are particularly useful for orally administrable anti-biotics, such as ampicillin, amoxycillin, cloxacillin, flucloxacillin, and the 5indanyl and. phenyl esters of carbenicillin, and other antibiotics useful in the treatment of gut infections. Such medicaments usually represent 1 to 15$ by weight of the formulation, suitably 3 to 10$ by weight of the formulation.

A polar solvent may also be advantageously incorporated into (.he formulations in order to increase the ease with which the oleophilic clays may be fully dispersed in the edible oil during the preparation of the formulation. It is necessary that the solvent be compatible with the medicament, non-toxic, substant rally more polar than the edible oil and miscible with the edible oil. For penicillins, a suitable polar solvent is propylene carbonate. The polar solvent may constitute from 0 to 2% by weight of the total formulation and in general the polar solvent will be present in the formulation in a weight that is 0 to 40$ of the weight of oleophilic clay.

The amount of oleophilic clay present in the formulation to produce the desired properties will normally be in the range of 0.1 to 25$ by weight. 6i4®a Obviously lower percentage inclusions will be preferred when a polar solvent is present, higher percentage inclusions preferred in the absence of a polar solvent. In general however 1 to 5% by weight of oleophilic clay will normally be most satisfactory, preferably in the presence of 0.1 to 2.0$ by weight of polar solvent, When the formulation is to be used for the treatment of an animal diarrhoea for scours, it may also be of advantage to include in the formulation a natural or synthetic clay absorbent. The amount of such clay present may be from 1 to 20$ by weight, preferably 5 to 15$ by weight, and examples of such clays include Bentonite and Atta15 pulgite.

The edible oil will usually represent the balance of the formulation, and will normally be present as at least 50$ by weight, suitably as at least 75$ by weight, of the formulation.

From the foregoing, it can be seen that a preferred embodiment of this invention is a pharmaceutical formulation as defined above which comprises 1 to 15$ by weight medicament, 1 to 5$ by weight oleophilic clay, 0.1 to 2.0$ by weight polar solvent, and edible oil to 100$. Into this preferred formulation may suitably be incorporated 5 to 15$ by weight of natural or synthetic clay absorbent in place of a corresponding percentage by weight of the edible oil.

In a further aspect, this invention provides a process for the preparation of a fluid pharmaceutical formulation which process comprises mixing a medicament - 7 41461 with a dispersion of an oleophilic clay in an edible oil. if a polar solvent, is to be used, it is normal to add the solvent to the dispersion of the clay in the oil before the mixing step with the medicament is carried out. Also, if a natural or synthetic clay absorbent is to be used, if is normally mixed into (he dispersion of the clay in oil at the same time as the medicament.

The clay in oil dispersion, optionally containing the polar solvent, is preferably passed through a colloid mill before it is mixed with the medicament and optional natural or synthetic clay absorbent. Similarly the final suspension is preferably passed through a colloid mill before use.

The invent.ion also provides a method of preventing or treating a disease in domestic animals, which method comprises the oral administration of a fluid pharmaceutical formulation as hereinbefore defined. The formulation is normally administered by means of a suitable dispenser, such as a nozzle connected to a bottle and plunger. A single dose may be for example 1 to 10 mis. of the suspension, containing a concentration of medicament which is in accordance with the recommended dosage of that medicament.

The formulation of the invention containing an appropriate medicament is of particular use in the treatment of animal diarrhoea or scours, and in particular in the treatment of neonatal scours in piglets.

The following Examples illustrate the invention: Example 1 The following formulation was prepared by the 5 method set out below: Bentone 38 (1) 1.5% w/v (i.e. 1.5 g/100 ml ) Propylene Carbonate 0.6% w/v Pharmasorb (2) 10% w/v Phosphoric Acid (3) 0,1% w/v Ampicillin Trihydrate 6.0% w/v as free acid Soya-Bean Oil to 100% (1) Bentone 38 is dimethyl diactadecyl ammonium hectorite, [Mg8LiSi12O3O(OH)6]©[(CH3)2N(Cl8H37)2]© (2) Pharmasorb is a brand of activated Attapulgite, Attapulgite having the approximate composition as defined earlier in the specification. (3) The phosphoric acid is present in a minor proportion to balance the alkaline pH of the Bentone.

The Bentone was dispersed in the soya-bean Oil, and when thoroughly distributed, the propylene carbonate was added with high speed mixing, followed by colloid milling to produce the base. Into this base was first mixed the phosphoric acid, and then the pharntasorb and I.lie penicillin, and l.lie rcsul l.ant suspension was then passed through a colloid mi ll once more.

Example 2 Example 1 was repeated, but using amoxycillin trihydrate in place of the ampicillin trihydrate.

Example 3 The following formulation method of Example 1: Bentone 27(l) Propylene Carbonate Pharmasorb Ampicillin Trihydrate Sunflower Oil was prepared by the 1.75% w/v 0.6% w/v 10,0% w/v 5.0% w/v to 100% (1) Bentone 27 is dimethyl benzyl octadecyl ammonium hectorite, [MggLiSi χ2°3O (°H) 61©[ (CH3 )2N ( C18H37 ) ( CH2)] © Example 4 Example 3 was repeated, but using amoxycillin trihydrate in place of the ampicillin trihydrate.

Claims

1. CLAIMS : 1. A fluid pharmaceutical formulation for oral administration to domestic animals which formulation comprises a medicament, an edible oil and oleo5 philic clay as hereinbefore defined.

2. A formulation according to Claim 1, wherein the oleophilic clay is a clay in which inorganic cations have been replaced by ammonium ions substituted by at least one a3 -kyl group. 10

3. A formulation according to Claim 2, wherein the substituted ammonium ions are of formula (I): where R^ is a C^ jg alkyl group, Rg is either a second ¢^2-18 alkyl group, a benzyl group, a C^_^ 15 alkyl group or hydrogen, and R^ and R^ are each a C^ alkyl group or hydrogen.

4. A formulation according to Claim 3, wherein R^ is a c -£2-l8 a lkyl group, R 2 is a alkyl group or a benzyl, methyl or ethyl group or hydrogen, and 20 R^ and R^ are each a methyl or ethyl group or hydrogen

5. - A formulation according to Claim 2, wherein the substituted ammonium ions are octadecyl ammonium, dimethyl mono- or dioctadecyl ammonium, dimethyl hexadecyl ammonium or dimethyl benzyl octadecyl ammonium 25 ions.

6. A formulation according Lo Claim 2, 3> or 5, wherein the clay is a montmorillonite,

7. A formulation according to Claim 2, 3j 4 or 5, wherein the clay is a hectorite.

8. A formulation according to Claim 2, 3, 4 or 5, wherein the clay is a hydrated magnesium aluminium silicate of the montmorillonite group of clays, but containing a higher magnesium content than normal montmorillonites and containing traces of calcium and iron.

9. A formulation according to Claim 1, 2, 3, 4 or 5, wherein the oleophilic clay is an Attagel.

10. A formulation according to any one of the preceding claims wherein the edible oil is sunflower oil, arachis oil, soya-bean oil, rapeseed oil or maize oil.

11. A formulation according to any one of the preceding Claims wherein the medicament is cloxacillin, flucloxacillin, or the 5-indanyl or phenyl ester of carbenicillin.

12. A formulation according to any one of the Claims 1 to 10, wherein the medicament is ampicillin.

13. - A formulation according to any one of the Claims 1 to 10, wherein the medicament is amoxycillin.

14. A formulation according to any one of the preceding Claims wherein the medicament is present as 1 to 15$ by weight of the formulation.

15. A formulation according to Claim 14, wherein the medicament is present as 3 to 10% by weight of the formulation.

16. A formulation according to any one of the 5 preceding Claims, wherein the oleophilic clay is present as 0.1 to 25% by weight of the formulation.

17. A formulation according to Claim 16, Wherein the oleophilic clay is present as 1 to 5% by weight of the formulation. 10

18. A formulation according to Claim 17, Wherein a polar solvent is present as 0.1 to 2.0% by weight of the formulation.

19. A formulation according to Claim 18, wherein the polar solvent is propylene carbonate. 15

20. A formulation according to any one of the preceding Claims, wherein a natural or synthetic clay absorbent is present as from 1 to 20% by weight of the formulation.

21. A process for the preparation of a fluid pharmac20 euticpl formulation for oral administration to animals comprising a medicament, an edible oil and an oleophilic clay, as hereinbefore defined, which process comprises mixing the medicament with a dispersion of the oleophilic clay in the edible oil. 25

22. A process according to Claim 21, wherein both the dispersion and the final formulation are passed through a colloid mill. - 13

23. A process as claimed in Claim 21 or Claim 22, wherein a polar solvent is mixed into the dispersion before addition of the medicament, and a natural clay absorbent is mixed into the dispersion at the same 5 time as the medicament.

24. A method of preventing or treating a disease in domestic animals, which method comprises the oral administration of a fluid pharmaceutical formulation according to Claim 1. 10

25. A method according Lo Claim 24, for the treatment of neonatal scours in piglets.

26. A process for preparing a fluid pharmaceutical formulation according to Claim 1 substantially as hereinbefore described in any one of the specific 15 Examples 1 to 4.

27. A fluid pharmaceutical formulation according to Claim 1, whenever prepared by a process according to any one of the Claims 21, 22, 23 or 26.