COX-2
inhibitors are the new wave in
chronic pain medication, better for you than the traditional
NSAIDs and less likely to make you an addict than the
opiates.
Celecoxib (sold as
Celebrex) is the older of the two COX-2 inhibitors on the market, released in the
USA in February of
1999 by
Searle. In May of 1999
Merck gained
FDA approval for
rofecoxib, which they
now sell sold before all the deaths as
Vioxx. Both were created to treat
rheumatoid and
osteoarthritis, but they are now indicated for
chronic pain and
cancer prevention.
Searle has another drug in the process of
FDA approval called
Valdecoxib, which is expected to be a terrifically powerful
non-narcotic analgesic, possibly usable instead of
morphine in some situations.
COX stands for Cyclo-oxygenase, a family of enzyme that comes in two flavors, COX-1 and COX-2. COX-1 is a friendly enzyme, it's present all the time in the digestive system and kidneys, and everywhere else in smaller quantities. COX-1 produces lots of prostaglandins, which are very important local hormones that control the behavior of the cell they are produced in and its surrounding cells. COX-1 is also important for activating platelets; without it the blood would be unable to clot.
COX-2 is only produced in response to tissue injury and causes tissue inflammation, and thus pain. It works converting arachidonic acid into a specific prostoglandin which communicates the need for inflammation to the surrounding tissue.
Now, regular NSAIDs (aspirin, ibuprofen, naproxen sodium, and pretty much everything else besides the opiates) work by inhibiting the entire COX class of enzymes equally. This knocks out the COX-2 enzyme, which is good because it stops pain. However, it also knocks out COX-1, which is bad, because it makes the body stop working properly, causing ulcers, liver damage, and a bit of neurotoxicity. Inhibiting COX-1 also deactivates some percentage of your blood's platelets, making the blood less viscous -- that's why people at risk for heart attacks should munch an aspirin every day.
COX-2 inhibitors are specific to the COX-2 enzyme, so they avoid all the side-effects of the traditional NSAIDs. (It should be pointed out that COX-2 inhibitors actually are NSAIDs, because they're non-steroidal.) COX-2 inhibitors select COX-2 well, and don't tend to interfere with COX-1 at all. Sicne an estimated 16,000 people die every year from NSAID/COX-1 damage, having specific COX-2 inhibition is pretty cool. Interestingly, some people who've been switched from their usual NSAID to a COX-2 inhibitor have had cardiovascular problems because there's no longer any blood thinning effect, so be careful.
On a personal note, when I tried Vioxx, it didn't work very well at all. I took half of a 50 mg pill, since it wasn't my prescription and I didn't want to get too much without knowing more about it. I didn't notice any effect on my headache or muscle pain at all, it seemed to be utterly ineffectual at that dose. I did however get some edema in my hands for about three days after taking the pill; on and off for that time it felt like my hands were asleep, which was pretty disconcerting. It also (and I haven't found a medical explanation for this yet) turned my depth perception way up. That is, for all of the time I had edema, I also had a really clear visual grasp on how far away things were, and how their distances related. It was quite hallucinatory, to tell you the truth.