Posted by Cam W. on December 20, 2001, at 1:05:42
In reply to Question For CAM About SSRI Withdrawal, posted by Geezer on December 19, 2001, at 16:00:53
Geezer - The withdrawl from both Paxilâ„¢ (paroxetine) and Effexor (venlafaxine) is caused by taking away the extra serotonin in the gap between nerves cells (synaptic cleft or synaptic gap) that these drugs cause by blocking the reuptake of serotonin back into the nerve cell that it was released from (the presynaptic neuron).
The postsynaptic neuronal membrane (the receiving nerve cell) has serotonin receptors in it to carry on the electrical impulse that is being transferred from the presynaptic neuron. The sudden decrease in the availability of serotonin to bind to these receptors causes the withdrawl symptoms.
If the amount serotonin is slowly decreased, as by a slow decreasing of dose over time (eg. lowering the dose by half every week or so), or using an SSRI with a long half-life (eg. Prozacâ„¢ - fluoxetine - which leaves the body much more slowly than Paxil or Effexor), the body has time to adjust to the decrease in serotonin. The body can either start producing more serotonin on it's own (which is what we are trying to do by taking antdepressants in the first place) or increase (or even decrease, depending upon the situation and genetics of the individual) the number of postsynaptic serotonin receptors.
Of course, the reality of this situation is not as simple as described above. One must also take into account what the decrease in serotonin does to other neurotransmitter, hormonal, etc. systems of the body (including those that involve norepinephrine).
The withdrawl symptoms, though, are what one would expect (for the most part) to happen when serotonin levels are lowered,
I hope that this rambling gives you an answer. - Cam
poster:Cam W.
thread:87444
URL: http://www.dr-bob.org/babble/20011213/msgs/87495.html