Single and multiple oral dose pharmacokinetics of tenoxicam in the elderly

Tenoxicam is a new non-steroidal anti-inflammatory drug with a long half-life. Since such drugs may be particularly prone to accumulate in elderly patients, a group of the population in which anti-inflammatory agents are most commonly prescribed, we have studied the pharmacokinetics of tenoxicam in 18 patients (age range 62-87 years) with osteoarthrosis or rheumatoid arthritis. A pharmacokinetic profile was performed after a single 20 mg oral dose. Patients then took regular medication until they had reached steady-state for chronic dosing (20 mg/day) when a further pharmacokinetic profile was performed. Approximately five-fold accumulation was found at steady-state (mean peak plasma level 2.6 micrograms/ml for a single dose against 12.4 micrograms/ml at steady-state). Twenty percent of the dose was eliminated in the first dose interval. Mean pre-dose plasma level at steady-state was 9.6 micrograms/ml with a coefficient of variation of 11%. Serial haematological and biochemical estimations during the study showed no evidence of drug toxicity.