Posted by Anthony Quest on May 29, 2004, at 15:35:32
In reply to What happens re: opiate tolerance? « kittencat, posted by Dr. Bob on May 29, 2004, at 7:18:51
Vicodin and other strong pain medications are pure Mu agonists. They work by stimulating endogenous opioid receptors throughout the body primarily in spinal cord and brain. The Mu, Kappa, and Delta opioid receptors are the best understood but there are likely several others.
Anyways, it is believed that repeated use desensitizes the opioid receptors and they become "upregulated". Why this happens is not known for sure. It is positied that the number of spare receptor becomes fewer, the receptors themselves become less dense, and the signaling between opioid molecule and the receptor is weaker. This is not gospel and hasn't been proven.
Herion addicts do die all the time because they lose their tolerance by taking a holiday or using something else.
It was thought that dextromethorphan hydrobromide (active ingredient) in over the counter cough syrup. There was a drug company I forget which one that was doing FDA clinical trials on a drug called Morphidex (Morphine and Dextomethophan) but the data showed no effect on tolerance.
Anyhow, a lot of people don't get euphoric from pain medication. Chronic pain suffers don't get buzzed from their pain meds, yet the medication is still quite efficicious for its analgesic effect. This is how addicts typically present - by frequent requests for increased dosage, seldom occurs in stable pain patients.
Hope that all helped.
> Posted by kittencat on May 28, 2004, at 5:39:21
>
> > Perhaps the wrong forum...but I'm just curious. Has anyone experienced tolerance to opiates such as Vicodin (increasingly larger doses, less effective pain relief, less of a sense of well being, etc.?) I know these effects will happen to anyone who is on any kind of synthetic opiate-based narcotic pain reliever for any extended period of time, but what I don't understand is why, when you completely taper off of the drug, & don't take it again for say, two months, the tolerance is still as high as if you had been continuously taking it when you begin again? (at least for me, it is). We all know there is a pretty enjoyable high (for most...not all) on these drugs...why does it subside, even after a long vacation from the drug? What happens in your brain that you continue to tolerate high doses & no longer feel "high", if you will? Does long term opiate use actually permanently alter the brain's chemistry?
> >
> > Any thoughts, facts, or guesses? Thanks...
>
>
poster:Anthony Quest
thread:351784
URL: http://www.dr-bob.org/babble/subs/20040409/msgs/351899.html