It all began in 1984 when the prestigious Noble Prize in Medicine was awarded for the revelation that the lowly drug Aspirin prevented the COX-2 enzyme from converting the biochemical arachidonic acid to pain-producing inflammatory end products.
Bonanza! Here was the solution to the unpatentable Aspirin: create competitor drugs that duplicated Aspirin’s inhibition of the COX-2 enzyme in people with pain. Lo and behold, very efficiently and rapidly, a new pharmaceutical industry was born. Imitation aspirins ultimately became known as NSAIDs (non-steroidal anti-inflammatory drugs) and were hailed as miracles of pharmaceutical innovation.
This well-known tale is now decades old. The billion dollar NSAID industry produced an untold number of candidate drugs; however, only a few were safe enough for clinical application. The survivor NSAIDs mimicked the pain-killing effects of Aspirin but never achieved its record of safety or the wide range of diseases in which it displayed significant health-promoting effects.
What went wrong? Excluding relief of pain, why did NSAIDs not behave the same as Aspirin as they were intended to do? The answer was provided a little over a decade or go by a brilliant young scientist named Charles Serhan who was virtually unknown outside his field of lipidomics. Serhan identified the biochemical mechanism used by Aspirin to kill pain.
Serhan’s studies of Aspirin’s interaction with the COX-2 enzyme revealed that the 1984 assumption that Aspirin inhibited the COX-2 enzyme was in error. Aspirin prevents arachidonic acid from being converted to inflammatory end products but NOT by inhibiting the COX-2 enzyme. Enzyme inhibition has a very specific meaning; an inhibited enzyme has turned off (inhibited) its ability to perform a function it normally performs.
The biochemical mechanism by which Aspirin interacts with COX enzymes is quite detailed; however, the outcome of the interaction is relatively easy to explain and be understood. In summary, Aspirin changes the function of the COX-2 enzyme so that it converts arachidonic acid to ANTI-inflammatory end products rather than inflammatory ones. As a result, pain is stopped and arachidonic acid can do no further damage because it ceases to exist.
By contrast, NSAIDs inhibit (turn off) the COX-2 enzyme thereby preventing arachidonic acid from being converted to inflammatory end products. The NSAID action stops the pain but the arachidonic acid spared by the NSAID is not acted upon, eliminated, or changed in any way. Instead it is sent to another inflammatory pathway to do it’s damage at another site.
In review, Aspirin prevents arachidonic acid from causing pain and from doing damage elsewhere. On the other hand, although NSAIDs kill pain, they do not interfere with arachidonic acid’s ability to cause mischief in other parts of the body. It does so by moving arachidonic acid to another inflammatory pathway. This transfer to another inflammatory pathway is a normal biochemical response for arachidonic acid when it is blocked from action by agents such as NSAIDs.
This difference between Aspirin and NSAIDs in the fate of targeted arachidonic acid is the key for why the miracle NSAIDs have caused sad, unintended consequences. By not eliminating arachidonic acid in the process of relieving pain, NSAIDs have failed in their goal of creating a substitute for Aspirin that would equal or surpass Aspirin’s excellent medical history.
The untended consequences rest in the totality of medical literature that show NSAIDs have created a new and significant source of medical ills. The failure of the goal may be forgiven, but the unintended consequences add an unacceptable medical burden on a society already under stress.