A comparison of isoxicam pharmacokinetics in young and elderly subjects.

1 The pharmacokinetics of isoxicam have been compared in 57 volunteers with an average age of 31.3 years and 48 elderly subjects with an average age of 71.9 years. 2 Isoxicam was given in a single daily dose of 200 mg for up to 22 days. Similar plasma concentrations were obtained in the two age groups, average maximum concentrations being 39.7 mg l-1 in those under 65 and 38.1 mg l-1 in the elderly. There were no significant differences in the half-life which averaged 30.4 and 32.1 h respectively. 3 Approximately 9% of all those studied had half-life values in excess of 50 h. The results are consistent with the possibility of genetic polymorphism of isoxicam hydroxylation. 4 It is concluded that isoxicam is suitable for use in once daily dosage and that there are no clinically significant differences in its pharmacokinetics between young and elderly subjects.