Journal of Bioequivalence & Bioavailability

Abstract

Comparative Bioavailability and Pharmacodynamic Aspects of Cyclobenzaprine and Caffeine in Healthy Subjects and the Effect on Drowsiness Intensity

Ronilson A. Moreno, Carlos Eduardo Sverdloff, Rogério A. Oliveira, Sandro Evandir Oliveira, Diego Carter Borges, Maristela H. Andraus, Myriam C. Salvadori and Ney Carter Borges

A specific, fast and sensitive LC–MS/MS assay was d e- veloped for the determination of cyclobenzaprine in hu- man plasma using imipramine as the internal standar d (IS). The limit of quantification was 0.05 ng/mL and the method was linear in the range of 0.05 to 50 ng/mL. The cyclobenzaprine and IS retention times were 2.74±0. 2 min and 2.69±0.2 min, respectively. Method intra-batch precision and accuracy ranged fr om 2.90 to 9.72%, and 91.63 to 107.33%, respectively. Inter- batch precision ranged from 3.37 to 10.27%, while I nter- batch accuracy ranged from 96.13 to 106.10%. The an a- lytical method was applied to evaluate the pharmaco ki- netic and relative bioavailability of two different pharma- ceutical formulations containing cyclobenzaprine, o ne test tablet containing 10 mg of cyclobenzaprine plus 60 mg of caffeine (Miosan ® /cafeine) and the reference Miosan ® con- taining only 10 mg of cyclobenzaprine, manufactured by the same pharmaceutical company. In addition to the phar- macokinetic analysis, a pharmacodinamic evaluation of the drowsiness intensity during the confinement per iods was conducted in order to evaluate the caffeine eff ect. This study evaluated 34 subjects in a randomized, 2-peri od crossover study with 14 days washout period between doses. Based on the 90% confidence interval of the individ ual ratios (test formulation/reference formulation) for C max and AUC inf , it was concluded that the test formulation is bioequivalent to the reference Miosan ® with respect to the rate and extent of absorption of cyclobenzaprine an d that caffeine had no effect on the relative pharmacokine tic pa- rameters. However, based on the Stanford point anal ysis, the combination of Miosan ® with caffeine in the same tab- let formulation significantly decreased the drowsin ess in- tensity observed during the confinement periods.