Posted by Cam W. on December 29, 2001, at 13:55:37
In reply to Re: selegiline patch vs. oral (Cam?) » spike4848, posted by Elizabeth on December 29, 2001, at 6:27:19
Elizabeth - I have not had much clinical experience with selegiline (Elderyl™), but I can posit a theory why the transdermal patch may be more effective. Aside from being concentrated in the liver, cytochrome enzymes are also found in the intestine. Now, I am not sure if Elderyl is metabolized via the cytochrome system, but if it is, then it could be that the phenomenon of "first pass" effect may be taking place.
As the Elderyl is being absorbed into the body, cytochrome enzymes could be metabolizing some of the molecule into it's metabolites, and further metabolism could be taking place in the liver, as general circulatory blood vessels from the the intestine pass through the liver before being distributed to the rest of the body. It is also known that Elderyl has an extremely short half-life.
By using a controlled (slow-release) transdermal patch, I would think that the selegiline avoids a majority of the first pass effect, hence more of the molecule will be active at more sites throughout the body (including the brain).
Also, the slower release of selegiline into by a transdermal patch would be like taking smaller doses over a longer period of time, thus you would expect better (ie. higher) blood levels of the parent drug, for longer periods, thus more efficacy.
As I say, I am guessing at this, but hey, it sounds like a fairly plausible explanation, and is probably what is going on.
As an aside, the only really interesting fact I do remember about selegiline is that 2 of its 3 major metabolites are amphetamine and methamphetamine. I wonder how much these contribute to its use in the psychiatric field. (This may have been mentioned; I have not been following any of the selegiline posts).
- Cam
poster:Cam W.
thread:87632
URL: http://www.dr-bob.org/babble/20011222/msgs/88164.html