A single dose, randomized, open-label, cross-over bioequivalence study of sildenafil citrate tablets in healthy Chinese volunteers .

Abstract

The present study was designed to evaluate the bioequivalence of a newly developed sildenafil citrate tablet 50 mg (Jinge^®, Test) and a marketed counterpart (Viagra^®, 100 mg, Reference) in healthy adult male Chinese volunteers. This single-dose, randomized, open-label, four-period, and two-treatment self-crossover study included two parts: fasting and postprandial studies. In each part of the study, the subjects were randomly assigned to receive test or reference products (100mg sildenafil) in a 1:1 ratio, and then received the alternative products, following a 1-week washout period. Plasma sildenafil concentrations were analyzed by liquid chromatography-tandem mass spectrometry. Tolerability was assessed during the entire study period. 32 healthy volunteers (aged 19-30) were enrolled in the study; 31 volunteers completed the fasting study, while 32 volunteers completed the postprandial study. The test formulation was bioequivalent to the marketed formulation as the 90% CIs for the ratio of geometric means of C_max (fasting: 98.79-119.61%; fed: 94.47-119.65%), AUC_last (fasting: 98.70-109.71%; fed: 96.39-112.89%), and AUC_∞ (fasting: 98.45-108.87%; fed: 96.36-112.74%) were within equivalence limits (80-125%) under both fasting and postprandial conditions. When sildenafil was given with high-fat meals, mean C_max was reduced by 23%, and median tmax ranged from 0.75 to 1.50 hours (p≤0.05). However, both AUC_last and AUC_∞ were comparable between fasting and postprandial conditions. No serious adverse events were found among the subjects. This study confirmed that test and reference sildenafil citrate tablets were bioequivalent under fasting and postprandial conditions. .