Pharmacokinetics of indomethacin in the elderly.

In a cross-sectional study the pharmacokinetics of indomethacin were studied in old and young adults without manifest organ failure. Total clearance of indomethacin after a single oral dose of 50mg was 0.8 ml/min/kg in elderly individuals (mean 79.5 +/- 1.3 years) compared with 1.4 ml/min/kg in younger individuals (mean 36.9 +/- 3.0 years). The apparent elimination rate constant averaged 0.23 h-1 in the aged and 0.32 h-1 in the young people. Oral bioavailability was close to 1 in the young but 0.77 in the elderly. The apparent volume of distribution was similar in each group. Based on these results it is suggested that the maintenance dose of indomethacin be reduced by 25% in the elderly.