Pharmacokinetic interaction study of a fixed combination of 500 mg acetylsalicylic acid/30 mg pseudoephedrine versus each of the single active ingredients in healthy male volunteers

Acetylsalicylic acid (CAS 50-78-2, ASA) and pseudoephedrine (CAS 90-82-4, PSE) both are remedies given together for the treatment of the symptoms of a common cold, i.e. mainly nasal congestion, running nose, sore throat and headache. The aim of this open, randomized, three-factorial (three-treatment, three-period, six-sequence) Latin Square clinical study was to investigate if there were any pharmacokinetic interactions between ASA and PSE when given as fixed combination of 500 mg ASA/30 mg PSE · HCl. Lack of interaction was assessed by determination of pharmacokinetic characteristics and relative bioavailability of both substances and salicylic acid (CAS 69-72-7, SA), administered in combination and as equally single dosed drugs. In total, the data of 12 healthy male volunteers were included into the pharmacokinetic evaluation. Primary target parameters were ratios combination/equally dosed single drugs of AUC norm and C max, norm of ASA, its metabolite SA and PSE. The primary target parameters were analyzed using an analysis of variance (ANOVA) after logarithmic transformation of the data. 90% confidence intervals were calculated for the geometric means of ratios using the mean square error term of the ANOVA. Results: Bioequivalence was given for AUC norm and C max, norm for all ratios calculated. No interaction was found for AUC norm and C max, norm between the fixed combination ASA/PSE and the equally single dosed drugs as reference. The supplementary evaluation for the non-normalized original parameters AUC and C max also revealed bioequivalence. All treatments were safe and well tolerated.