Pharmacokinetics of melatonin sustained release tablets and common tablets in Beagle dogs

Objective: To compare the in vivo pharmacokinetic parameters of melatonin sustained release tablets and common tablets in Beagle dogs.Methods: Three-way crossover design was used.Six Beagle dogs orally took 6 mg melatonin sustained release tablets,melatonin common tablets,or foreign sustained release tablets.Then,plasma concentration was determined by a LC-MS-MS method and calculated.Results: Pharmacokinetic parameters of the 3 preparations were as follows: Cmax,(8.929±5.220),(29.653±14.503) and(8.196±4.723) ng·mL-1;Tmax,(1.140±0.608),(0.250±0.051) and(1.083±0.492) h;t1/2,(1.723±1.080),(0.946±0.548) and(1.105±0.308) h;MRT,(1.834±0.651),(0.784±0.637) and(1.617±0.296) h;AUC0-12,(13.832±6.967),(12.272±5.623) and(14.190±7.003) ng·mL-1·h;AUC0-∞,(13.873±6.941),(12.308±5.556) and(14.216±7.004) ng·mL-1·h.Conclusion: Compared with the common tablets,the sustained release tablets show slower absorption,longer peak time,lower peak concentration,and longer duration.The 3 formulations are bioequivalent.