GB1569018A

GB1569018A - Preparations of 3-n-pyrrolidino-4-phenoxy-5-sulphamyl-benzolc acid and process for their manufacture

Info

Publication number: GB1569018A
Application number: GB50915/77A
Authority: GB
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1976-12-07
Filing date: 1977-12-07
Publication date: 1980-06-11
Also published as: ES464642A1; FR2373280A1; NZ185855A; PT67370B; ATA873777A; DE2655331A1; IE46005L; AU513409B2; JPS5372815A; BE861608A; AT355216B; DK542877A; IL53539A0; FR2373280B1; PT67370A; ZA777204B; NL7713392A; AU3127477A; IE46005B1

Description

(54) PREPARATIONS OF 3-N-PYRROLIDINO 4-PHENOXY-5-SULPHAMYL-B ENZOIC ACID AND PROCESS FOR THEIR MANUFACTURE (71) We, HOECHST AKTIENGESELL SCHAFT, a body corporate organised according to the laws of the Federal Republic of Germany, of 6230 Frankfurt/Main 80, Postfach 80 03 20, Federal Republic of Germany, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to pharmaceutical preparations comprising 3 N- pyrrolidino- 4- phenoxy - 5 sutphamyl - benzoic acid (piretanide) which has the formula

Slow release medicaments are used when it is desirable to maintain in the blood a constant level of an active substance over a prolonged period of time in order to achieve an even effect. Moreover, the compatibility may also be improved. Slow release medicaments are therefore especially useful when therapy is to be extended over a prolonged period of time.

Treatment with a saluretic agent, either alone or in combination with one or more further therapeutic substances, for example, reserpine or a - methyl - dopa, is often continued for many months, for example, in the case of hypertonia. Piretanide is a saluretic that is especially suitable for long term treatment, particularly of hypertonia, and in many cases it is desirable to influence the activity of piretanide by means of a slow release composition in such a way that the resulting diuresis is levelled out over several hours.

Numerous galenic methods are available for retarding the release of an active substance and thus for retarding its absorption. The most frequently used methods are embedding the active substance in a lipophilic substance or in a hydrophilic swelling agent, or incorporating it in a matrix of a synthetic polymer material. In order to improve the compatibility and to achieve an even action over a prolonged period of time, especially for oral administration, there are preferred sustained release preparations comprising coated granules or pellets which comprise the active substance. As coating materials there may be used, for example, fats, waxes, resins, derivatives of cellulose, polymeric derivatives of (meth)acrylic acid and copolymers with maleic anhydride. These materials may be either spread on the granules or pellets directly as solutions, or applied by spraying or by fluidization. The fact that the active substance is distributed on numerous slow release particles helps to ensure an even development of the action of the active substance.

The in vitro release values of such retarding compositions are more than 15% after about one hour in an acid medium of pH 1.2, and more than 30 to 40 /n of the active substance is released after another hour at pH 5.5. The total period of retarded release may be often up to 8 hours or even more.

In contrast to slow release preparations, a rapidly disintegrating tablet releases the active substance completely within practically one hour. In the case of piretanide, this results in a strong temporary diuresis within the first hour.

The present invention provides a pharmaceutical preparation suitable for the treatment of hypertonia, which comprises 3 - pyrrolidino - 4- phenoxy - 5 sulphamyl- benzoic acid as active substance and which has an in vitro release of the active substance measured in the flow-through cell according to Dibbern (cf.

Pharmazeutische Zeitung vol. 116 (1971) pg.

1848-1853) of not more than 5% after 75 minutes in a buffer solution of pH 1.2 and after a further period of 60 minutes in a buffer solution of pH 5.5, of not more than 25% of the total active substance.

Especially suitable are preparations from which the piretanide is released at the rate of 2 to 5% within 75 minutes and of 9 to 20% within 135 minutes.

This release pattern results in vivo in a mild diuresis that continues for several hours, so that preparations from which the active substance is released in vitro in the above manner are especially suitable for treating hypertonia.

The development of the in vitro release of piretanide from a piretanide retarding composition according to the present invention (Example 1), measured in the flow cell according to Dibbern, is shown in curve 3 of the accompanying drawing, the slowly ascending curve showing the slow release within the first 135 minutes which characterizes the preparation of the invention and on which depends the long term diuresis in vivo, an effect which could not be expected.

In vitro release according to Dibbern of the preparation of Example 1: after 75 minutes at pH 1.2 4% after a total of 135 minutes 9% (75 minutes at pal.2, 60 minutes at pH 5.5) After this period of time, as shown by the curve, the active substance is released rapidly and unspecifically at pH 7.5, the active substance being released almost quantitatively after a total of 4 hours. The rapid release at pH 7.5 is due to the good solubility of the film-forming agent used at pH 7.5. Curve 2, which represents the release from a conventional retarding composition, does not differ substantially from curve 3 in the alkaline pH range because the same film-forming agent is used.

The conventional retarding composition used to produce curve 2 has the following composition: neutral pellets 742.35 mg polyvinyl pyrrolidone 14.85 mg piretanide 14.85 mg talc 207.85 mg shellac 6.47 mg stearic acid 13.14 mg aluminum hydroxide gel 0.49 mg 1000.00 mg In vitro release according to Dibbern: after 75 minutes pH 1.2 11% after a total of 135 minutes 27% (75 minutes pH 1.2, 60 minutes pH 5.5) The release rate is clearly higher in the first 135 minutes than is the release rate of the composition according to the present invention. Slow release compositions having in vitro indices as indicated in curve 2 or even higher indices do not have the desired effect of an even diuresis over several hours, but they lead to short-lived relatively strong diuresis.

Curve I indicates the in vitro availability of piretanide from a piretanide-containing tablet of the following composition: piretanide 3.00 mg lactose 50.00 mg corn starch 24.00 mg hydroxyethyl cellulose 1.50 mg magnesium stearate 0.25 mg talc 1.25 mg 80.00 mg The release characteristics of a piretanide slow release preparation are critical for its use in a long term treatment and this release behaviour provides a distinctive difference between the retarding compositions claimed herein and conventional retarding compositions.

Preparations having the desired release characteristics may be obtained by coating particles or granules consisting of or comprising piretanide with a coating material that disintegrates in a slightly acid medium. The term "slightly acid medium" is used herein to mean a medium having a pH within the range of from 4.5 to 6.5.

It is preferable to coat particles or granules with piretanide and generally an adhesive or binder.

It is preferable to use neutral pellets with the most regular granular size possible for absorbing the active substance, in order to ensure an even distribution of the active substance and a well balanced release of active substance. To achieve this, inert pellets which, preferably have an average diameter of from 0.6 mm to 1.0 mm, are preferably wetted with a solution of an adhesive or binder, advantageously an alcoholic adhesive solution in a coating vessel; polyvinyl pyrrolidone is generally used, but other synthetic polymers are also suitable adhesives or binders. The active substance is then applied to the wetted pellets. Good results have been obtained when the piretanide is admixed with a filler, especially talc. This step of coating is carried out only once or may be repeated as often as required until the total quantity of active substance has been applied.

The coating material which imparts the characteristic release properties in a slightly acid medium is preferably applied to the dried pellets consisting of or comprising the active substance by means of a continuous spraying operation.

A low boiling point organic or aqueous liquid, for example, an alcohol, ester, ketone or water, or a mixture of two or more thereof, may be used as the solvent; a cellulose compound, a mixture of shellac and stearic acid or a derivative of poly(meth)acrylic acid is preferably used as a film forming agent capable of disintegrating in a slightly acid medium. As a rule, a film-forming solution contains one or more plasticizers and/or further additives.

In order to achieve the desired release characteristics and the corresponding retarding effect, there is applied for example from 4.8 to 5.6%, preferably about 5% of a film coating when using a mixture of shellac and stearic acid, or from 11.5 to 12.5, preferably about 12% of film coating when using an acrylic resin, calculated on the weight of the neutral pellets, which preferably have a size within the range of from 0.7 to 0.85 mm.

It is a common practice that particles coated with an active substance and a retarding lacquer film are combined to form a larger dose unit, for example, by filling the coated particles into a capsule, generally a snap-fit capsule. It is important that no initial dose and no mixture with particles of various coat thicknesses are needed. There is no risk of a loss of active substance and restrictions of availability to be reckoned with.

The following Examples illustrate the invention.

EXAMPLE 1: 1. neutral pellets 0.7 to 0.85 mm 28.08 mg 2. polyvinyl pyrrolidone K 25 14.56 mg 3. piretanide 14.56 mg 4. talc 203.87 mg 5. shellac 12.68 mg 6. Stearic acid 25.76 mg 7. aluminum hydroxide gel 0.49 mg (1) is wetted in a coating vessel with an alcoholic solution of (2), and a mixture of (3) and (4) is introduced by dusting on. The coated pellets are further coated with a film composed of (5) and (6), and (7) is dusted on.

About 310 mg of retarding pellets which correspond to a 4.5 mg content of piretanide are introduced into snap-fit capsules.

In-vitro release rate in the flow cell according to Dibbern: after 75 minutes pH 1.2 4% after 135 minutes pH 5.5 9% EXAMPLE 2: 1. neutral pellets 0.7 to 0.85 mm 688.99 mg 2. polyvinyl pyrrolidone K 25 13.78 mg 3. piretanide 13.78 mg 4. tale 192.92 mg 5. acrylic resin 81.85 mg 6. glycerol triacetate 8.19 mg 7. aluminium hydroxide gel 0.49 mg (1) is wetted with (2) in a coating vessel and then coated with a mixture of (3) and (4). The pellets containing active substance are coated with a film composed of (5) and (6), and dusted with (7). Approximately 325 mg of retarding pellets-corresponding to a 4.5 mg content of piretanide-are introduced into snap-fit capsules.

In-vitro-release in the flow cell according to Dibbern: after 75 minutes pH 1.2 2% after 135 minutes pH 5.5 17% WHAT WE CLAIM IS: 1. A pharmaceutical preparation comprising 3 - N - pyrrolidino - 4phenoxy - 5 - sulphamyl - benzoic acid as active substance, wherein the in vitro release rate of the active substance in the flow cell according to Dibbern is not more than 5% of the total after 75 minutes in a buffer solution of pH 1.2, and not more than 25% of the total after a further 60 minutes in a buffer solution of pH 5.5.

2. A pharmaceutical preparation as claimed in claim 1, wherein the in vitro release rate of the active substance is from 2 to 5% within 75 minutes at pH 1.2 and from 9 to 20% after a further 60 minutes at pH 5.5.

3. A pharmaceutical preparation as claimed in claim 1, or claim 2, which comprises particles consisting of or comprising the active substance and coated with a coating material capable of disintegrating in a slightly acid medium.

4. A pharmaceutical preparation as claimed in claim 3, which comprises neutral pellets having an average diameter of from 0.6 mm to 1.0 mm and which are coated with the active substance.

5. A pharmaceutical preparation as claimed in claim 3 or claim 4, wherein the particles are coated with the active substance and an adhesive or binder.

6. A pharmaceutical preparation as claimed in claim 5, wherein the adhesive or binder is polyvinyl pyrrolidone.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. carried out only once or may be repeated as often as required until the total quantity of active substance has been applied. The coating material which imparts the characteristic release properties in a slightly acid medium is preferably applied to the dried pellets consisting of or comprising the active substance by means of a continuous spraying operation. A low boiling point organic or aqueous liquid, for example, an alcohol, ester, ketone or water, or a mixture of two or more thereof, may be used as the solvent; a cellulose compound, a mixture of shellac and stearic acid or a derivative of poly(meth)acrylic acid is preferably used as a film forming agent capable of disintegrating in a slightly acid medium. As a rule, a film-forming solution contains one or more plasticizers and/or further additives. In order to achieve the desired release characteristics and the corresponding retarding effect, there is applied for example from 4.8 to 5.6%, preferably about 5% of a film coating when using a mixture of shellac and stearic acid, or from 11.5 to 12.5, preferably about 12% of film coating when using an acrylic resin, calculated on the weight of the neutral pellets, which preferably have a size within the range of from 0.7 to 0.85 mm. It is a common practice that particles coated with an active substance and a retarding lacquer film are combined to form a larger dose unit, for example, by filling the coated particles into a capsule, generally a snap-fit capsule. It is important that no initial dose and no mixture with particles of various coat thicknesses are needed. There is no risk of a loss of active substance and restrictions of availability to be reckoned with. The following Examples illustrate the invention. EXAMPLE 1: 1. neutral pellets 0.7 to 0.85 mm 28.08 mg 2. polyvinyl pyrrolidone K 25 14.56 mg 3. piretanide 14.56 mg 4. talc 203.87 mg 5. shellac 12.68 mg 6. Stearic acid 25.76 mg 7. aluminum hydroxide gel 0.49 mg (1) is wetted in a coating vessel with an alcoholic solution of (2), and a mixture of (3) and (4) is introduced by dusting on. The coated pellets are further coated with a film composed of (5) and (6), and (7) is dusted on. About 310 mg of retarding pellets which correspond to a 4.5 mg content of piretanide are introduced into snap-fit capsules. In-vitro release rate in the flow cell according to Dibbern: after 75 minutes pH 1.2 4% after 135 minutes pH 5.5 9% EXAMPLE 2: 1. neutral pellets 0.7 to 0.85 mm 688.99 mg 2. polyvinyl pyrrolidone K 25 13.78 mg 3. piretanide 13.78 mg 4. tale 192.92 mg 5. acrylic resin 81.85 mg 6. glycerol triacetate 8.19 mg 7. aluminium hydroxide gel 0.49 mg (1) is wetted with (2) in a coating vessel and then coated with a mixture of (3) and (4). The pellets containing active substance are coated with a film composed of (5) and (6), and dusted with (7). Approximately 325 mg of retarding pellets-corresponding to a 4.5 mg content of piretanide-are introduced into snap-fit capsules. In-vitro-release in the flow cell according to Dibbern: after 75 minutes pH 1.2 2% after 135 minutes pH 5.5 17% WHAT WE CLAIM IS:

1. A pharmaceutical preparation comprising 3 - N - pyrrolidino - 4phenoxy - 5 - sulphamyl - benzoic acid as active substance, wherein the in vitro release rate of the active substance in the flow cell according to Dibbern is not more than 5% of the total after 75 minutes in a buffer solution of pH 1.2, and not more than 25% of the total after a further 60 minutes in a buffer solution of pH 5.5.

7. A pharmaceutical preparation as

claimed in any one of claims 3 to 6, wherein the particles are also coated with a filler.

8. A pharmaceutical preparation as claimed in claim 7, wherein the filler is talc.

9. A pharmaceutical preparation as claimed in any one of claims 3 to 8, wherein the coating material capable of disintegrating in a slightly acid medium is a cellulose compound, a derivative of poly(meth)acrylic acid, or a mixture of shellac and stearic acid.

10. A pharmaceutical preparation as claimed in claim 9, which comprises from 4.8 to 5.6% of a coating comprising a mixture of shellac and stearic acid, or 11.5 to 12.5% of a coating comprising an acrylic resin.

11. A pharmaceutical preparation as claimed in any one of claims 3 to 10, wherein a plurality of the coated particles are in a larger unit dosage form.

12. A pharmaceutical preparation as claimed in claim 11, wherein the larger unit dosage form is a capsule containing the coated particles.

13. A pharmaceutical preparation as claimed in claim 12, wherein the capsule is a snap-fit capsule.

14. A pharmaceutical preparation as claimed in claim 1, substantially as described in Example 1 or Example 2 herein.

15. A process for preparing a preparation as claimed in claim 1, which comprises coating particles consisting or comprising the active substance with a coating material capable of disintegrating in a slightly acid medium, the coating material being such that the coating being carried out in such a way that the active substance is released from the preparation at the rates specified in claim 1.

16. A process as claimed in claim 15, wherein the particles comprising the active substance are neutral pellets having an average diameter of from 0.6 to 1.0 mm.

17. A process as claimed in claim 15 or claim 16, wherein the particles are wetted and the active substance is dusted on.

18. A process as claimed in claim 17, wherein the particles are wetted with a solution of an adhesive or binder.

19. A process as claimed in claim 18, wherein the particles are wetted with an alcoholic solution of polyvinyl pyrrolidone.

20. A process as claimed in any one of claims 17 to 19, wherein the active substance is an admixture with a filler.

21. A process as claimed in claim 20, wherein the filler is talc.

22. A process as claimed in any one of claims 17 to 21, wherein the active substance is applied to the particles more than once.

23. A process as claimed in any one of claims 15 to 22, wherein the coating material capable of disintegrating in a slightly acid medium is a cellulose compound, a poly(meth)acrylic acid or a derivative thereof, or a mixture of shellac and stearic acid.

24. A process as claimed in claim 23, wherein there is applied to the particles from 4.8 to 5.6% of a coating comprising a mixture of shellac and stearic acid or 11.5 to 12.5% of a coating comprising an acrylic resin.

25. A process as claimed in any one of claims 15 to 24, wherein the coating is sprayed onto the particles.

26. A process as claimed in any one of claims 15 to 25, wherein the coated particles are brought into a larger unit dosage form.

27. A process as claimed in claim 26, wherein a plurality of the particles are filled into a capsule.

28. A process as claimed in claim 15, carried out substantially as described in Example 1 or Example 2 herein.

29. A pharmaceutical preparation as claimed in claim 1, whenever produced by a process as claimed in any one of claims 15 to 28.