A common complaint of chronic pain patients is constipation caused by the opiates they are on. If I understand things correctly, you could give oral naloxone to these patients which would solve the constipation by out-competing the pain medication for the opiate receptors in the gut, while at the same time it would not go to the brain in significant amounts if taken orally if I understand things correctly - and so the opiates would still do their job of being a pain killer.
Since that is such an obvious thing to do it obviously isn’t done for a reason. What is that reason?
Indeed I googled this before posting this question and I found this intriguing statement:
which suggests that it *is *done in Holland, in which case the question becomes “why is this not standard”?
semi-facetously, doctors are nervous about the <quavery echo voice> evils of druuuuuuug addiction <end voice> that pain control sucks ass for anybody with chronic pain conditions. They are also nervous about being deemed a “Doctor Feel-Good” so they do things like leave stage 4 cancer patients screaming in their deathbeds [unless like my uncle you actually start up on heroin and are tranked off your ass for the last 6 months] New medications are seen with suspicion in the US and tend to take years to grudgingly be approved for use.
Me? I started using an illegal substance that can be grown anywhere there is sunlight and dirt … not that I recommend this to anybody though I am gratified that it has started being decriminalized in many areas for small amounts. Makes my liver and kidneys happier too.
Naloxone would reverse the analgesic effect of opiates. So, to relieve the constipation (but not interfere with a narcotic’s pain relieving effect), docs actually use a relative of naloxone called methylnaltrexone. Methylnaltrexone doesn’t enter the brain so doesn’t oppose the analgesic effect of narcotics. But, it does work on the gut to counteract their effect at that site.
Interesting in theory, but I’ve talked to a few addictionists who report that a LOT of opioid-habituated patients tend to dislike Methylnaltrexone, as it does seem to give them enough withdrawal symptoms to make them acutely uncomfortable.
I really didn’t know that. Shows . . . I’m too far removed from reality!
In fact, I do remember reading that some of the analgesic effect of opiates is mediated via peripheral receptors. In other words, even if methylnaltrexone doesn’t cross the blood brain barrier it may still antagonize some of the analgesic effect of narcotics.
Naloxone has a very low oral bioavailability, so the theory is that giving the medicine orally will counteract the effects of opiates on the gut without interfering with any of the desired CNS effects. I’ve tried it a few times in the Emergency Department for opiate induced constipation without any success. I did a brief review of the literature at the time and there wasn’t much evidence it was effective there either. In the end I ended up giving Rx for Golytely and sending them home with a pat on the back.
Well, interestingly enough. Apparently loperamide sold as Immodium has some mild euphoria associated with extremely high doses. This is inspite of the fact that it isn’t supposed to cross the blood brain barrier as well. So who knows, perhaps, it works both ways and marginally small amounts cross for both drugs, enough to cause discomfort, or mild euphoria.
As someone who, due to nerve damage from a rare form of spinal cord injury, must rely on regular, extremely high doses of loperamide just in order to maintain any degree of consistency, let me say that I have never experienced euphoria-mild or otherwise-from my admittedly voluminous use of this drug. I do worry about ill effects long term, though, but have no other course of action in sight.
