Preparation of tramadol hydrochloride controlled-release tablets and evaluation of its bioavailability in dogs

Objective:To prepare tramadol hydrochloride controlled-release tablets and to evaluate its relative bioavailability in dogs.Methods:Tramadol hydrochloride controlled-release tablets were prepared with cellulose acetate as coating materials,polyethylene glycol 400 as pore-forming agents.In a randomized,crossover,and single-dose study,the tramadol concentration in dog plasma was measured by HPLC after an oral administration of 200 mg commercial conventional tablets or controlled-release tablets.Results:The pharmacokinetic parameters were as follows,AUC0~∞(10 230.6±2 312.1) and(10 808.8±1 794.3)ng·h·mL-1,Cmax(1 670.6±252.3) and(812.7±94.3)ng·mL-1,Tmax(2.0±0.4) and(7.5±1.9) h,for conventional and controlled-release tablets respectively.Conclusion:Tramadol hydrochloride controlled-release tablets had well controlled-release characteristics in vivo,and the relative bioavailability was(107.0±8.2)%.Furthermore,the correlation of pharmacokinetics in vivo and release in vitro was good for controlled-release tablets.