FOERFARANDE FOER FRAMSTAELLNING AV KRISTALLINT NATRIUM- OCH KAIUMCEFALEXINMONOHYDRAT

1413066 Cephalosporins BRISTOL-MYERS CO 8 June 1973 [8 June 1972] 27456/73 Heading C2C Stable crystalline forms of sodium cephalexin monohydrate and potassium cephalexin monohydrate, which are characterized by specific X-ray diffraction data, are produced by dissolving cephalexin in an organic solvent in the presence of at least one equivalent of an organic amine to form a solution and reacting the solution in the presence of water with a preformed solution of a sodiun or potassium salt of an aliphatic carboxylic acid to precipitate the desired crystalline product. The cephalexin may be in the form of its monohydrate, which is dissolved in an halogenated hydrocarbon, an aliphatic alcohol or acetonitrile in the presence of water and a tertiary amine such as triethylamine and reacted with the sodium or potassium salt of an aliphatic carboxylic acid in an anhydrous solvent. Alternatively, the cephalexin may be in its anhydrous form which is dissolved in an anhydrous solvent and reacted with the sodium or potassium salt of the aliphatic carboxylic acid in a solvent containing water. The compounds may be used in the treatment of bacterial infections in man, with suitable carriers or excipients, in an amount of from 5 to 125 mg./kg./day of active ingredient.