Posted by Pops_1 on June 14, 2006, at 13:22:24
In reply to Re: EMSAM doses too low to effect depression ?, posted by notfred on June 14, 2006, at 10:33:34
Your original speculation - that EMSAM doesn't require dietary restrictions b/c it is essentially equivalent to sub-therapeutic oral selegline dose levels - is interesting but incorrect on two points.
(See http://www.cnsspectrums.com/aspx/articledetail.aspx?articleid=400 for excellent overview of MAO Inhibitors and EMSAM's pharmokinetics).
1. Transdermal delivery has very different pharmokinetics than oral delivery. Since it enters the bloodstream directly, it has much stronger effect than oral dose, which much of which is metabolized before it can reach brain to inhibit MAO A & B.
"The bioavailability of selegiline is ~75% following STS compared with 4.4% after oral administration due to first-pass metabolism. Therefore, STS produces higher and more sustained steady-state levels compared with oral selegiline."
"STS also was 10–20 times more potent than oral selegiline in producing its antidepressant-like effect and inhibiting cortical MAO-A."
2. Dietary restrictions aren't require despite the higher potency of transdermal selegiline because transdermal delivery doesn't inhibit the MAO-A in the gut to the extent oral selegline dose. If your gut MAO-A are OK, you can still eat tyramine-rich foods.
"Doses of [Selegiline Transdermal System] that inhibit brain MAO-A and MAO-B by 60% and 90%, respectively, do not alter [gastro intestinal] MAO-A activity."
Hope that explanation is clear...
poster:Pops_1
thread:655515
URL: http://www.dr-bob.org/babble/20060610/msgs/656885.html