Posted by Vanillintabaktöne on June 7, 2004, at 19:28:49
In reply to Re: Help - Trileptal/Heart racing (nm), posted by Vanillintabaktöne on June 7, 2004, at 6:40:08
The exact same thing happened to me with carbamazepine @ 200 mg CR twice a day.
Carbamazepine [Tegretol] and oxcarbazepine [Trileptal] are chemically related to the Tricyclic Antidepressants. They too had the same effect on me in terms of heart racing, although lesser with Imipramine. Even the older antihistamines like diphenhydramine [Benadryl] Dimenhydrinate [Gravol] and Chlorpheniramine [Piriton] all do that.
This effec is because of the tertiary amine on the molecule resulting in anticholinergic effects. Anticholinergic and sympathomimetic [adrenergic] effects are somewhat similar in that the both oppose vagal tone resulting in tachycardia, although with anticholinergics there is the clear distinction of sedation and memory loss amongst other things. In otherwards ZOMBIE!!
The only difference between Tegretol and Trileptal was the addition of an oxygen to the former to lessen hepatic effects with the resulting Trileptal. However, Trileptal still possessess anticholinergic properties which MAY explain why users experience tachycardia. The Na+ channel blockade may also be the reason. But whether selectivity exists for different channels [cerebral or extracerebral]
, I dont know. It is interesting to note that the Na+ channel blockade property is one that all the mood stabilizers possess, and that Na+ valproate also causes cardiac effects in some individuals including myself especially at doses exceeding 500 mg per day. So this may be a more plausible explanation.It is important to realize that stimulation of the 5-HT-2 receptor by endogenous serotonin or other ligands this receptor has affinity for can result in considerable anxiety. It makes sense that the net increase in 5-HT availability secondary to reuptake inhibition by the SSRI's can result in anxiety [paradoxic] and nausea through stimulation of 5-HT-3 receptors. Although Prozac, Paxil, Zoloft, Celexa and Lexapro OBVIOUSLY increase serotonin, each agent exhibits secondary binding affinities, with maybe the exception of citalopram and escitalopram [which still bind to histaminergic receptors in the CNS], and produce unwanted side effects or welcomed benefits.
IMPORTANTLY TOO, CONSIDER THAT ALL ANTIDEPRESSANTS RESULT IN DOWNREGULATION AND INCREASE SENSITIVITY OF CNS ADRENERGIC RECEPTORS AND THROUGH REGULATION OF ADENYL CYCLASE.
Case in point Paxil which is the most sedating SSRI because of intrinic affinty for muscarinic receptors, FURTHER opposing vagal tone and potentially producing the tachycardia, and the 'zombie', 'zonked' demeanour in your case.
In my opinion, NOT A GOOD COMBO.
Further it should also make pharmacologic sense that SSRI's not be a good choice to add to bipolars. Although it does seem to work in some individuals, for which I have no theories on. Considering 5-HT receptor stimulation effects especially by acute stimulation can result in deleterious effects. Just consider that the antipsychotics, the atypicals especially, exhibit considerably more blockade at 5-HT-2 receptors than at D-2 and are more often than not effectively used to treat Bipolar Affective Disorder states.
So maybe in your case, combining a less antimuscarinic SSRI's or even an atypical antidepressant Be combined with a low dose of an atypical antipsychotic like Seroquel be better for you. It would produce a nefazodone-like effect without stewing your liver.
It is food for thought.
P.S. I think there is a combo out there that consists of Prozac and an atypical Antipsychotic in one pill. Cant remember the name.
poster:Vanillintabaktöne
thread:354398
URL: http://www.dr-bob.org/babble/20040602/msgs/354627.html