Posted by harryp on May 28, 2004, at 22:32:12
In reply to MAOI and Alpha-2 Antagonist (Yohimbine) » harryp, posted by Questionmark on May 28, 2004, at 16:15:15
I'll try to find out more about Yohimbine.
Phentolamine is a non-selective a1+a2 antagonist, and I'm not sure if a a2 alone would do the trick--I'll do some more reading.
I've dug through all the hypertension/MAOI literature I could find on Medline and medical texts to find the best drugs for a MAOI hypertensive crisis. Here's a summary:
The general consensus now is that Nifedipine is too unpredictable in its action to be a good choice for treating a hp crisis. Some people have experienced heart attacks or hypotension from using it. (It may still be better than nothing).
Phentolamine is the "gold-standard" in all the literature. It is very safe and difficult to OD on, because it only blocks the effect of sympathomemetic amines (i.e. tyramine, norepinephrine). It would have little or no effect on the bp of someone who didn't already have sympathomemetic amines in their bloodstream.
The only problem with MAOI hp crises is that they are very rare (just as MAOI's are rare) and many ER personel do not know the proper treatment and what drugs are contraindicated. This is why I feel one should carry a signed chart and instructions. Phentolamine is not a common drug and is often not stocked. (Labetalol is an acceptable substitute, but must be used more cautiously).
Thorazine is listed in some of the literature as an effective treatment. I haven't seen any information on self-administration, though. I would be very reluctant to take a drug that would turn me into a drooling moron (possibly for days) if I were far from home and needed to make decisions, drive, etc.
The best solution, in my opinion, would be to develop something similar to the "epi-pen" that would allow a patient to easily inject 5mg phentolamine intramuscularly (phentolamine can be injected IM, although that slows the onset and lengthens the half-life--[which could be a superior arrangement far from an ER]).
I believe that this would be the safest and most effective way to control a hp crisis if good medical care were not available.
Hopefully, if the backlash against the SSRI's continues (check out David Healy's *Let them Eat Prozac*--published by NYU press.) MAOI's may become more popular. A self-administrated pen injection system could increase the ease of mind for doctors and those patients who need MAOI's and have the good judgement to use them correctly.
poster:harryp
thread:348520
URL: http://www.dr-bob.org/babble/20040527/msgs/351694.html