title: Bioavailability of commercial tetracycline products.
abstract: 1 Thirteen commercial tetracycline products were assessed for bioavailability by in vitro and in vivo tests. Three failed the B.P. disintegration test and three products in a dissolution test released less than 50% of their stated potency by 3 hours. 2 In vivo bioavailability was assessed by serum and urinary data. Six products were tested by serum data over 48 h and their bioavailability profiles varied but their ranking correlated well with in vitro dissolution in water; three were better than the others. In a further study, based on urinary excretion alone, the thirteen products showed considerable variation in bioavailability. One product gave an extremely poor result (6 mg excreted in 24 hours). 3 These findings of generic non-equivalence illustrate the need for adequate standards of bioavailability testing.
authors.affiliation: Section of Therapeutics, Academic Division of Medicine, University of Sheffield, Royal Infirmary, Sheffield.
authors.forename: D B
authors.initials: DB
authors.lastname: Barnett
authors.forename: R N
authors.initials: RN
authors.lastname: Smith
authors.forename: N D
authors.initials: ND
authors.lastname: Greenwood
authors.forename: C
authors.initials: C
authors.lastname: Hetherington