Lack of influence of glycine on the single dose pharmacokinetics of acetylsalicylic acid in man.

Galenic formulations consisting of acetylsalicylic acid and glycine were developed to improve solubility of the drug, even in case of ingestion without intake of water. It was the aim of this study to investigate the potential influence of glycine on pharmacokinetics after single oral administration of 1,000 mg of acetylsalicylic acid. Therefore, a bioequivalence study using a randomized crossover design (reference = without glycine, test = with glycine) in 12 healthy male volunteers (age 22 - 38 (median 26) years, body weight 64 - 83 (median 75) kg) was performed. Pharmacokinetic characteristics (AUC, Cmax, tmax, t1/2, MRT) were taken or calculated on the basis of plasma concentration/time profiles. For both acetylsalicylic acid and salicylic acid the 90% confidence intervals of the ratios of the expected median values (microT and microR) for the primary characteristics AUC and Cmax of the test and reference formulation were included in the equivalence range of 80 - 125%, which in case of multiplicative model is accepted for concluding bioequivalence. Therefore, lack of influence of glycine on the pharmacokinetics of acetylsalicylic acid including its major metabolite salicylic acid was concluded.