The idea for using Ultra Low dose Naltrexone (ULDNTX) came after I saw an article in the Medical Post regarding some research that Dr. Jhamandas et al had done in rats using doses in the range of 0.05 femtograms of naltrexone to enhance morphine analgesia and to prolong the actions of morphine. I immediately emailed Dr. Jhamandas and he gave me a number of references involving the use of Naloxone (another opiate antagonist with roughly half the potency of naltrexone) in potentiating morphine in PCA post-operative analgesia.

A PCA pump allows a patient to inject a dose of morphine when they start to experience pain postoperatively. This results in greater patient comfort and decreased nursing workload. As the morphine doses injected are small (1-2 mg) fine titration of pain control is possible without excess sedation. The experiment that Dr. Jhamandas referred me to was a study in which 0.25 micrograms of naloxone/hour was given by continous IV infusion (this normally occurs in PCA as a slow flow of fluid must be maintained to keep iv from clotting), and this miniscule dose decreased the amount of moriphine that patients used by 30%.

From my readings in this area over the last 3 weeks, it appears that one is dealing either with a morphine receptor which has two states; one that increases pain and the other which decreases pain. Morphine in ultra-low doses appears to increase pain in rats, but this experiment has never been done in humans to the best of my knowledge. It appears that Naltrexone has a higher affinity for this receptor than the standard opiate receptors that mediate classical opiate analgesia (this would most likely be the mu receptor).

The other possibility is that one of the endogenous opiates actually increases pain, and that this opiate is increased in states of opiate tolerance. Right now I don't know enough to distinguish between the possibilities.

There are some very exciting possibilities here in that it may be possible to prevent opiate tolerance from developing, and in people who are very sensitive to the unpleasant side effects of opiates, pain relief may be possible without feeling like a zombie. It may even be possible that ULDNTX alone may work as an analgesic in some people as chronic pain does cause upregulation of endogenous opiate production.

RSN there will be more references on this site and clearer explanations of what I think is happening.

Naltrexone may be obtained in several ways; it is available as a prescription tablet in a dose of 50 mg at which dose range it is used to help people stay off heroin. DON'T take this high a dose of Naltrexone if you are on opiates and have developed tolerance; it will put you immediately into withdrawal, and this state may last for 24 hours.

The upper end of the dose range that I will be giving patients is 1 mg, and I expect that oral doses will range from 10-100 micrograms every 4-8 hours based on preliminary data from the first few people who have tried it

There are other uses for naltrexone, and references to all indications will be here soon.

(C) Dr. Boris Gimbarzevsky 1/4/2002