Formulation of Low Dose Medicines - Theory and Practice

Reprinted from American Pharmaceutical Review, Volume 3 Issue 3 For further information please contact: Russell Publishing LLC Tel: 317-816-8787 Fax: 317-816-8788 Email: [email protected] Progress in pharmaceutical research has produced very potent drugs, which require careful formulation and production in order to produce solid oral dosage forms with acceptable homogeneity and physical stability. Assuring the physical stability of a powder blend for production of tablets or capsules represents a major quality assurance consideration. The content uniformity quality control procedure for most tablets and capsules which are the subject of official monographs is by the analysis of mean drug content of 20 tablets which have been ground together (B.P., 1973). Train (1960) realizes that such an assay procedure could provide a satisfactory mean value, even though individual tablets showed large variations about the mean. The B.P. recognized the importance of the problem when in 1973 it introduced a requirement of individual tablet assay for “microdose” preparations (tablets containing less than 2 mg or 2% w/w of active drug). As well as specific problems associated with interpretation of the data, which such assays, provide (Orr and Sallam, 1978); there are also more general problems such as inability to detect batches where loss of homogeneity has occurred up until the testing of the finished product. Secondly, such late testing provides no information concerning the point of failure nor the mechanism by which content uniformity has been lost. In order to solve both specific and general problems associated with current pharmacopeial testing, a simple reproducible and informative test is required, by which tablet content uniformity under realistic processing conditions can be assessed. This test should have the following criteria (Staniforth et al, 1989):