Relative bioavailability of lorazepam tablets in healthy volunteers

OBJECTIVE To study pharmacokinetics and bioavailability of lorazepam in 18 young healthy volunteers.METHODS The lorazepam concentrations in plasma were determined by HPLC after a single oral dose of the standard formulation and the tested formulation were respectively given to 18 volunteers in randomized cross-over test.RESULTS The concentration-time curves of two formulations fitted to a one-compartment open model. The C_ max was ( 36.9± 9.1) μg·L -1and ( 38.2± 10.2) μg·L -1, T_ max was ( 2.5± 0.7) h and ( 2.5± 0.7) h, T_ 1/2ke was ( 15.8± 3.0) h and ( 15.4± 2.8) h, AUC_ 0~t was ( 578.8± 176.5) μg·h·L -1and( 589.8± 193.5) μg·h·L -1, AUC_ 0～∞ was ( 702.0± 162.9) μg·h·L -1and ( 699.1± 197.8)μg·h·L -1,respectively.The pharmacokinetic parameters obtained from the study showed no significant difference between two formulations(P 0.05). The relative bioavailability was( 102.6± 14.0)% of the tested formulation.CONCLUSION The results of statistical analysis suggest that the two formulations be bioequivalent.