Comparative pharmacokinetics of midazolam and loprazolam in healthy subjects after oral administration

✍ Scribed by R. Jochemsen; P. A. Van Rijn; T. G. M. Hazelzet; C. J. Van Boxtel; D. D. Breimer

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 397 KB
• Volume: 7
• Category: Article
• ISSN: 0142-2782
• DOI: 10.1002/bdd.2510070108

✦ Synopsis

The pharmacokinetics of oral midazolam (Dormicum@, 15 mg) and loprazolam (Dormonoct@, 1 mg) were studied in eight healthy young volunteers in a cross-over design. Plasma concentrations of midazolam were measured with a gas chromatographic method and loprazolam concentrations were determined by a radio-receptor technique. Absorption of midazolam proceeded very rapidly (median t,,, = 0.4 h) and a rapid onset of sedative action was observed. Loprazolam absorption was relatively slow (median tmax = 3 h) and its absorption profile was often irregular. Most subjects fell asleep before peak concentrations were reached. Median peak concentrations were 94 ng ml-' and 3.1 ng ml-' for midazolam and Ioprozolam, respectively. The median elimination half-life of midazolam was 1.8 h and that of loprazolam 15 h. It is possible that the elimination half-life of loprazolam as determined by radioreceptor assay is determined by active metabolites rather than by loprazolam itself. Midazolam elimination half-life was the same when determined by radioreceptor assay or by GLC. There was no significant correlation between the half-lives of the two drugs.