Pharmacokinetics of piroxicam in man.

Piroxicam is a potent antiinflammatory agent currently in widespread use for the treatment of various inflammatory conditions of man. Following single oral doses of 10 to 100 mg, piroxicam is rapidly and fully absorbed, and eliminated with a mean plasma half life of about 45 hr. Mean peak concentrations are about 2 micrograms/ml after single 20 mg doses and about 6 micrograms/ml at steady state with 20 mg daily. Multiple peaking suggests enterohepatic recirculation of drug. In accord with expectations, steady state is achieved within 7 to 12 days with no appreciable accumulation thereafter. Due to the long plasma half life, once daily dosing provides continuous exposure to drug, with concentrations fluctuating less than twofold. Coadministration of aspirin reduces piroxicam levels by about 20 percent; antacids have no effect on piroxicam plasma concentrations.