Multi-step vs. single-step resistance evolution under different drugs, pharmacokinetics, and treatment regimens.

Valdecoxib is an orally administered, highly selective cyclo-oxygenase (COX)-2 inhibitor with anti-inflammatory and analgesic properties. In well designed trials, valdecoxib demonstrated efficacy versus placebo in patients with osteoarthritis (OA), rheumatoid arthritis (RA), primary dysmenorrhoea and postoperative pain. Initial results in patients with migraine headache were promising. The efficacy of valdecoxib appears dose dependent up to 40 mg/day. Valdecoxib 10 mg/day was as effective as naproxen and rofecoxib in improving signs and symptoms of OA. The American College of Rheumatology 20% response rate was similar in recipients of valdecoxib, naproxen and diclofenac in patients with RA. In patients with dysmenorrhoea, valdecoxib 20 or 40 mg up to twice daily provided as effective pain relief as naproxen sodium 550 mg twice daily. In acute post-surgical pain, single-dose valdecoxib 40 mg had a rapid onset of action, provided similar analgesia to oxycodone 10 mg plus paracetamol (acetaminophen) 1000 mg and provided a longer time to rescue medication than rofecoxib or oxycodone/paracetamol after oral surgery. Pre-emptive administration of valdecoxib 10-80 mg was particularly effective in dental pain. Valdecoxib had opioid-sparing effects after hip or knee arthroplasty and reduced pain after laparoscopic cholecystectomy. Valdecoxib is generally well tolerated. The incidence of gastroduodenal ulcers was generally lower than with nonselective NSAIDs (i.e. NSAIDs not specifically developed as selective COX-2 inhibitors). With concomitant aspirin, the ulcer rate in valdecoxib recipients increased significantly, but was still lower than that in recipients of aspirin plus nonselective NSAIDs. In conclusion, valdecoxib, a COX-2-selective inhibitor, is as efficacious in pain relief as nonselective NSAIDs, with better gastrointestinal tolerability. It was as effective in RA, OA and primary dysmenorrhoea (the approved indications) as nonselective NSAIDs and as effective as rofecoxib in RA flare. In acute post-surgical pain, valdecoxib provided similar pain relief to oxycodone/paracetamol, had a long duration of action, a rapid onset of analgesia and was opioid-sparing. Valdecoxib provides a valuable alternative in the treatment of chronic arthritis pain and acute pain.