Posted by djmmm on May 20, 2003, at 18:14:24
In reply to Re: Parnate pharmacology., posted by Paulie on May 20, 2003, at 12:18:58
> I noticed more stimulation on 20mg/d parnate than on 45mg/d nardil. What's interesting is that on nardil my MAO inhibition must have been anywhere in the range of approx. 40-95%. On parnate MAO inhibition was probably no greater than 25%. This data is from http://www.vh.org/adult/provider/psychiatry/CPS/17.html
> There is also a chart correlating parnate dosing with MAO inhibition-http://www.vh.org/adult/provider/psychiatry/CPS/17Figure2.html
>
> This is total MAO activity. Wish they had separated into MAO-A and MAO-B. Being that parnate is very dopaminergic it probably is a much stronger MAO-B inhibitor than nardil.
> There was a person who overdosed on 400mg parnate. Autopsy showed no trace of any amphetamine metabolites.
> Being chemically related to amphetamine may account for some stimulant effect. It could possibly be a catecholamine activity enhancer like deprenyl even at very low doses is believed to be.
>
> Paul
>I think Parnate has some agonist properties, in adition to it's primary MAO inhibition, it has some use as an antiparkinsonian med. Unfortunately that chart is a little misleading since the dose is mg/kg in relation to weight. At a theraputic dose, either MAOI will irreversibly bond to monoamine oxidase A and B in the 80% range. Even still, the majority of studies on MAO inhibition show little correlation between the theraputic effects of MAOIs and the % of inhibition.
Parnate and Nardil are very different drugs, with numerous metabolites, phenylethylidenehydrazine, a metabolite of Nardil, increases GABA levels, this is unique to phenelzine, as is its ability to downregulate 5-ht2 receptors. Phenelzine is also unique in that it seems to greatly increase serotonin levels (after long term treatment) while levels of catecholamines remain lower (although obviously increased)..and this variation is independent of nearly equal MAO-A/MAO-B inhibition.
After being on both meds Parnate is more stimulating, in a classical stimulant way (at times my eyes were dialated, my heart beat a little faster, etc) While Nardil, although far from sedating, had a mild euphoric quality, I suppose due to it's effects on GABA.
poster:djmmm
thread:227776
URL: http://www.dr-bob.org/babble/20030520/msgs/227951.html