title: Piroxicam and naproxen plasma concentrations in patients with osteoarthritis: relation to age, sex, efficacy and adverse events.
abstract: Piroxicam and naproxen plasma concentrations were obtained after 4 weeks active therapy between 3 and 12 hours post-dose in 640 and 629 patients, respectively. These patients are a subset of 2,035 patients with osteoarthritis on whom we have reported previously (11) in a double-blind multicentre safety and efficacy trial comparing piroxicam 20 mg/day and naproxen 750 mg/day. The purpose of the present study was to look for an association of plasma drug concentration with the variables of: age, sex, adverse events and efficacy. There was a statistically significant increase in plasma concentrations of both drugs with increasing age and females had higher concentrations than males. The increase in plasma concentration seen with increasing age was of a magnitude of 25% for piroxicam and 20% for naproxen when comparing a 50 year old to an 80 year old. However, less than 15% of the variability in plasma concentrations seen between patients is accounted for by age and sex. Within the plasma concentrations achieved with these doses, no association with adverse events, non-serious or serious, and efficacy was noted.
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002986:Clinical Trials as Topic; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D009288:Naproxen / Q000009:adverse effects / Q000097:blood* / Q000627:therapeutic use; D010003:Osteoarthritis / Q000188:drug therapy / Q000378:metabolism*; D010894:Piroxicam / Q000009:adverse effects / Q000097:blood* / Q000627:therapeutic use; D011446:Prospective Studies; D011897:Random Allocation; D012737:Sex Factors
chemical_list: D010894:Piroxicam; D009288:Naproxen