Efficacy of a single daily dose of a nonsteroidal anti-inflammatory drug with an intermediate plasma half-life: A double-blind, comparative trial of acemetacin and piroxicam

Abstract

It has been proposed that the duration of the analgesic and anti-inflammatory effects of nonsteroidal anti-inflammatory drugs (NSAIDs) is longer than that expected from the plasma half-life values, with the possible exception of the salicylates. To determine the veracity of this statement, we conducted a double-blind clinical trial to compare piroxicam, an NSAID with a long half-life (about 40 hours) and acemetacin, an NSAID with an intermediate half-life (about 6 hours). Fifty-six patients of both sexes with a mean age of 54 years and with a clinical and radiologic diagnosis of osteoarthritis of the hip or the knee were enrolled. The initial treatment regimen consisted of a single daily capsule of either piroxicam 20 mg or acemetacin 90 mg to be taken at breakfast. The patients were instructed to take a second capsule at dinner whenever the single dose was found to be insufficient. Both drugs were shown to have substantial analgesic and anti-inflammatory activity and were equally effective. Ten (17.9% of the total study population) patients took more than one capsule a day. All of these patients had severe symptoms at the beginning of the trial, but eight patients required two capsules for only a brief period of 2 to 5 days. Thus only two patients (3.6% of the study population) required a regular twice-daily regimen. Acemetacin appeared to be better tolerated than piroxicam. Our results confirm that the duration of the clinical effects of NSAIDs cannot be predicted from their half-lives only.