Relative bioavailability of the compound paracetamol and amantadine hydrochloride tablets in healthy volunteers

Objective To study the pharmacokinetics and relative bioavai- lability of two domestic compound paracetamol and amantadine hydrochloride tablets in 20 Chinese healthy volunteers. Methods A single oral dose of two tablets of test or reference drugs were given to each volunteer according to an open randomized crossover design. Theophylline was used as the internal standard and the concentrations of paracetamol and caffeine in plasma were determined by HPLC method. The pharmacokinetic parameters were calcutated by DAS program and the bioequivalence were compared. Results The pharmacokinetic parameters of the test and the reference tablets for paracetamol were as follows: C_ max were (7.31±1.15) and (7.25± 1.49) mg·L~ -1; t_ max were (0.91±0.37) and (1.04±0.52) h;t_ 1/2 were (3.71±0.30) and (3.77±0.45) h; AUC_ 0-16were (31.17±5.50) and (30.74±5.76) mg·h·L~ -1; AUC_ 0-∞ were (32.57± 5.94) and (32.22±6.25) mg·h·L~ -1, respectively. The pharmacokinetic parameters of the test and the reference tablets for caffeine were as follows: C_ max were (0.80±0.11) and (0.79±0.13) mg·L~ -1; t_ max were (0.98±0.27 ) and (1.04±0.49) h;t_ 1/2 were (4.86±1.19) and (4.42±1.09) h; AUC_ 0-24 were (5.83±1.34) and (5.29±1.50) mg·h·L~ -1; AUC_ 0-∞ were (6.15±1.46) and (5.57±1.59) mg·h·L~ -1, respectively. The relative bioavailability of test to reference tablets were (102.10±10.97) % for paracetamol and (113.37±22.66)% for caffeine. Conclusion The test and reference formulations were bioequivalence for both the paracetamol and caffeine compositions.