PRAVASTATIN EXTRACTION
The present invention provides a method for the purification of pravastatin comprising extracting a solution comprising pravastatin in a water-immiscible solvent with water at a pH value ranging from 5.0 to 7.0.
1 . A method for the purification of pravastatin comprising extracting a solution comprising pravastatin in a water-immiscible solvent with water or an aqueous solution characterized in that said extraction is carried out at a pH value ranging from 5.0 to 6.5 and that said water-immiscible solvent is an acetate or a ketone.
2 . Method according to claim 1 further comprising isolating pravastatin from the aqueous phase obtained after said extracting.
3 . Method according to claim 1 wherein said pH value is ranging from 5.5 to 6.5.
4 . Method according to claim 1 wherein said acetate is chosen from the list consisting of ethyl acetate, iso-butyl acetate, methyl acetate and propyl acetate and said ketone is methyl iso-butyl ketone.
5 . Method according to claim 1 wherein said extraction is carried out in a counter-current mode or in a cross-current mode.
6 . A composition comprising pravastatin and compactin in which the ratio pravastatin:compactin is higher than 500:1.
7 . Pravastatin sodium comprising less than 0.15% compactin.