Posted by SLS on June 9, 2006, at 8:07:19
In reply to Re: MAOI and epinephrine » SLS, posted by Caedmon on June 8, 2006, at 18:21:42
Hi Chris.
Thanks for taking the time to respond.
I would still be scared to be given epinephrine or norepinephrine while taking an MAOI.
Unfortunately, the quotation you provided does not report the dosages of MAOI that were used. In the case of anaphylaxis, the patient was taking only 15mg of Nardil. I doubt that such a low dosage would produce a degree of MAO inhibition that would be representative of a therapeutic level.
I really don't know what to think. I have safely combined high dosages of Parnate with TCA and dextroamphetamine, both of which are indirect sympathomimetics. I understand the rationale for why a direct receptor agonist might not be dangerous, but still...
Thanks again.
- Scott> Anaphylaxis and monoamine oxidase inhibitors—the use of adrenaline
> M J Fenwick and C L Muwanga
> J Accid Emerg Med 2000; 17:143-144
> http://emj.bmjjournals.com/cgi/content/full/17/2/143 [link to full text]
>
> ~~~
>
> There is also this:
>
> "It is unclear if there is an interaction between MAOIs and vasoconstrictors. The termination of the pharmacological response to epinephrine is not primarily dependent on monoamine oxidase. Thus, exogenous epinephrine should not be appreciably affected by the administration of a MAOI. In one study, four healthy subjects took MAOIs and were given IV epinephrine. No significant effect on heart rate or blood pressure occurred. This same study also showed no interaction between norepinephrine and MAOI. Hansten and Horn have reported that MAOIs may slightly increase the pressor response to norepinephrine and epinephrine, an action which appeared to be due to receptor sensitivity caused by the MAOI (Drug Interactions and Updates, PD Hansten and JR Horn (eds.), 1990, Malvern, PA: Lea and Febiger) It is currently accepted practice to use caution when administering local anesthetic with vasoconstrictor in patients medicated with MAOIs."
>
> - http://www.lexi.com/web/dentistry.jsp?id=wynn_january06
>
> ~~~
>
> - Chris
poster:SLS
thread:654285
URL: http://www.dr-bob.org/babble/20060604/msgs/654777.html