# US 5,705,192 A · Method of producing flowable R,S-thioctic acid, R,S-thioctic acid and its use > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,705,192 A - Document ID: US5705192A - Status: Granted - Kind: A - Application number: 08/618,790 - Filed: 1996-03-20 - Granted: 1998-01-06 - Earliest claimed: 1995-03-21 - Assignees: Asta Medica Aktiengesellschaft - Inventors: Horst Bethge; Kurt Klostermann; Roland Moller; Gerhard Sator - Web page: https://patentgrep.com/patent/US5705192A ## CPC - A61K 9/1688: {resulting in pure drug agglomerate optionally containing up to 5% of excipient} - A61K 31/385: having two or more sulfur atoms in the same ring - A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D) ## Abstract 1. A method of producing flowable R,S-thioctic acid, R,S-thioctic acid and its use. 2.1. Known methods of preparing flowable thioctic acid which can be galenically further processed by pressing to highly-concentrated, solid presentations with active-substance contents of more than 200 mg pure substance require the mixing of the thioctic-acid forms of different origins and/or a spraying on of galenic adjuvants from aqueous solution and a subsequent grinding process in order to arrive at a pressable granulate. 2.2. As a result of the fact that thioctic acid of any origin is placed in the fluid bed of a device suited for producing a fluid bed and that a built-up granulate consisting of thioctic acid is obtained by spraying a solution of thioctic acid of any origin onto the matter placed in the fluid bed under simultaneous removal of the solvent, it is possible to make a thioctic-acid form available which does not adhere to the pressing tool or exhibit a tendency to form fissures on the tablet even when tablets with 600 mg or more active-substance content are prepared. The novel R,S-thioctic acid has a specific surface of >0.7 m.sup.2 /g and a number of mesopores with a diameter between 2 and 30 nm. ## Claims ### Claim 1 A method of producing flowable R,S-thioctic acid which can be further processed galenically by pressing to highly concentrated solid presentations with contents of more than 200 mg pure thioctic acid, said method comprising the steps of placing a stationary phase of thioctic acid in a fluid bed, and spraying a solution of thioctic acid onto the thioctic acid placed in the fluid bed while simultaneously removing solvent; to obtain a flowable granulate of thioctic acid. ### Claim 2 (depends on 1) The method according to claim 1, wherein said stationary phase is solvent-moist thioctic acid. ### Claim 3 (depends on 1, 2) The method according to claim 1 or 2, wherein said stationary phase is more than 10% by weight and less than 50% by weight relative to the total weight dry thioctic acid, said total weight being the sum of the stationary phase and sprayed-on thioctic acid. ### Claim 4 (depends on 3) The method according to claim 3, wherein said stationary phase is approximately 25% by weight relative to the total weight dry thioctic acid. ### Claim 5 (depends on 2) The method according to claim 2, wherein the solvent-moist thioctic acid has been prepared by dissolving one part thioctic acid at 10.degree. C. to 60.degree. C. in 5-20 parts solvent or solvent mixture and cooling said mixture within 2 to 10 hours to 0.degree. C. to -20.degree. C., said solvent or solvent mixture having a relative permittivity .epsilon. between 2.5 and 5.5. ### Claim 6 (depends on 1, 2) The method according to claim 1 or 2, wherein a highly-concentrated solution of thioctic acid is sprayed onto the stationary phase while adjusting product temperature, spray pressure and spray rate so that solvent evaporates and thioctic acid crystallizes out. ### Claim 7 (depends on 6) The method according to claim 6, wherein the solution of thioctic acid is sprayed into the fluid bed with a temperature in a range of 0.degree. to 60.degree. C. ### Claim 8 (depends on 6) The method according to claim 6, wherein spraying is carried out at 100 to 1200 mbar. ### Claim 9 (depends on 1, 2) The method according to claim 1 or 2, wherein the solution of thioctic acid comprises aromatic, aliphatic or cycloaliphatic, organic solvents. ### Claim 10 (depends on 9) The method according to claim 9 wherein the solution of thioctic acid comprises acetone or ethyl acetate. ### Claim 11 (depends on 9) The method according to claim 9, wherein the concentration of the solution of thioctic acid is between 10 and 80%. ### Claim 12 (depends on 1) The method according to claim 1, wherein a flowable product with a bulk weight between 500 and 900 g/l is obtained which has a grain-size distribution and particle quality suitable for being galenically further processed to solid presentations or for being pressed into highly-concentrated, solid presentations. ### Claim 13 (depends on 1) The method according to claim 1 wherein a product is obtained with a residual solvent content of organic solvents of <1000 ppm. ### Claim 14 A composition of R,S-thioctic acid which has a specific surface of >0.7 m.sub.2 /g and a number of mesopores with a diameter between 2 and 30 nm. ### Claim 15 (depends on 14) The composition according to claim 14, wherein the volume of the mesopores with a diameter between 2 and 30 nm is between 0.001 and 0.005 ml/g per gram R,S-thioctic acid. ### Claim 16 (depends on 14, 15) The composition of claim 14 or 15, wherein the ratio of the volume of mesopores with a diameter between 2 and 30 nm per gram R,S-thioctic acid to the volume of macropores with a diameter >30 nm per gram R,S-thioctic acid is between 1:1000 and 1:10. ### Claim 17 (depends on 16) The composition of claim 16, wherein the ratio is between 1:200 and 1:50. ### Claim 18 (depends on 1, 2) A medicament which is produced by the method of claim 1 or 2. ### Claim 19 (depends on 14) A medicament comprising the composition of claim 14.