title: Purity requirements from a pharmacopoeial point of view.
abstract: The nature of pharmacopoeial specifications for bulk drug substances 25-30 years ago and the analytical methods used at that time are briefly reviewed. Since then the concept of characterizing drug substances by controlling impurities has been developed in pharmacopoeias. This concept is examined in relation to: pitfalls in practice; the precision and specificity of analytical procedures; the purity of many drugs nowadays; the usefulness of assays of drug substances; specifications for drug substances for which new methods of synthesis have been used; control of impurities in formulated products; and the significance of purity of drug substances and formulated products.
authors.affiliation: British Pharmacopoeia Commission Secretariat, Market Towers, Nine Elms Lane, London SW8 5NQ, UK.
authors.forename: C A
authors.initials: CA
authors.lastname: Johnson