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Dr. Bob is Robert Hsiung, MD,
[email protected]Shown: posts 1 to 9 of 9. This is the beginning of the thread.
Posted by sdb on April 8, 2005, at 15:21:16
I have read it should be a weak noradrenaline/serotonin/dopamine reuptake inhibitor
Most say "pro sexual" effect is caused by increased noradrenaline and dopamine and antidepressant activity also.
In contrast trazodone has pro libido effects (nobody knows why) and pro erection effects (everybody knows) why.
(I personally dont like to much noradrenaline transmission, because of negative experience)
What is true? Does somebody know something or is there some good literature/abstracts?
Posted by mworkman on April 8, 2005, at 15:35:07
In reply to What is wellbutrin (bupropion) pharmacologically?, posted by sdb on April 8, 2005, at 15:21:16
I believe wellbutrin works mostly on noradrenaline and also on dopamine to a lesser extent.
Posted by Maxime on April 8, 2005, at 15:45:53
In reply to What is wellbutrin (bupropion) pharmacologically?, posted by sdb on April 8, 2005, at 15:21:16
Hi.
Wellbutrin is chemically unrelated to tricyclic, tetracyclic, selective serotonin re-uptake inhibitor, or other known antidepressant agents. Its structure closely resembles that of diethylpropion; it is related to phenylethylamines.
It is a relatively weak inhibitor of the neuronal uptake of norepinephrine, serotonin, and dopamine, and does not inhibit monoamine oxidase.Hope this helps.
Maxime
> I have read it should be a weak noradrenaline/serotonin/dopamine reuptake inhibitor
>
> Most say "pro sexual" effect is caused by increased noradrenaline and dopamine and antidepressant activity also.
>
> In contrast trazodone has pro libido effects (nobody knows why) and pro erection effects (everybody knows) why.
>
> (I personally dont like to much noradrenaline transmission, because of negative experience)
>
> What is true? Does somebody know something or is there some good literature/abstracts?
>
>
Posted by mattw84 on April 9, 2005, at 18:33:21
In reply to Re: What is wellbutrin (bupropion) pharmacological, posted by Maxime on April 8, 2005, at 15:45:53
Well said Maxime -- it does fall under the class of phenylthylamines, as do many CNS stimulant drugs. Wellbutrin acts largely on dopamine and has a minor effect on noradrenaline and norepinepherine.
I believe the root chemical structure of burpropion is also lesser referred to as keto-amphetamine. Which has 3 or 4 active metabolites, which have up to a 60 hour half-life.
This likely explains the much different side effects than that of the SS/SNRI group. The phenylthylamine family includes a number of compounds, most of which are stimulating and thusly act on dopamine -- which is thought to be the most powerful chemical producing a psychoactive "pleasure" response.
Don't know if that made any sense... but Wellbutrin is the only antidepressant in it's class, which is too bad as it is generally very effective. Good luck!
Matt
Posted by sdb on April 10, 2005, at 3:39:23
In reply to Re: What is wellbutrin (bupropion) pharmacological, posted by mattw84 on April 9, 2005, at 18:33:21
Thank you matt for your response.
Bupropion seems to resemble to Cocaine!
So, I think its more activating and not good to combat anxiety. But the fact that it has minor effect on noradreanline transmission seems to be a positive effect (for people with anxiety in depressive episodes).
Where have you read that bupropion only has minor effect on noradrenaline transmission? -I dont like noradrenaline transmission because its causing tremor, tachycardia. For depressive individual this is ok (activating), but for bp with anxiety it is not. I had this experience with mirtazapine, which when plasma levels rose increased noradranline transmission and i had a terrible panic attack!
I am not experienced with dopamine enhancing drugs. One positive aspect is that trazodone increases indirectly steroid production in adrenal gland (!) trough 5ht2 affinity and therefore secretion of acth from the pituitary gland (more libido). And second positive aspect is the approx. 1/10 alpha2/alpha1 blocking properties which dilates blood vessels in sinus cavernous (pro erectional).
Posted by sdb on April 10, 2005, at 4:04:31
In reply to Re: What is wellbutrin (bupropion) pharmacological, posted by sdb on April 10, 2005, at 3:39:23
Very interesting article which could explain pro libido effects of trazodone:
Cattedra di Neuropsichiatria Infantile, Universita di Firenze.
We report the case of a 19 month old girl with myoclonic encephalopathy of infants (MEI) (Kinsbourne syndrome), on long-term therapy with ACTH for the occurrence of frequent relapses (steroid-dependent form). The administration of trazodone per os at low doses as an alternative to the previous treatment ensured complete remission, also on the occasion of a subsequent relapse. No rebound effects were observed after trazodone withdrawal (10 months). At present, 3 years after withdrawal of the therapy, the child is well and free from symptoms. The hypothesis that trazodone may be effective in treating MEI, at least in cases that are steroid-dependent or resistant to ACTH, appears highly interesting. Trazodone is proposed as a possible alternative to treatment with ACTH.
PMID: 1318289
Posted by mattw84 on April 10, 2005, at 15:24:05
In reply to Re: What is wellbutrin (bupropion) pharmacological, posted by sdb on April 10, 2005, at 3:39:23
Sdb,
You are correct in that wellbutrin tends to be quite anxiogenic for patients predisposed for it. However, in spite of this it is still the 'best' AD for bipolar individuals as it is the least likely trigger manic episodes.
Interestingly enough -- though not a labelled or off-label treatment for social anxiety, previous studies show that it is effective for this indication in many cases... Quite the paradox to what one would anticipate.
Trazadone on the other hand, has amongst the highest affinities for serotonin , which people tend to attribute only to it's influence on emotion. In fact -- only 5% of one's serotonin is found in the brain. This chemical also controls many other functions in the body. The cause of priapism can likely be explained by the vasoconstrictive properties of serotonin. It also plays many other roles in the body, thus the numerous unwanted and often unexplainable side-effects of tricyclic and heterocyclic antidepressants...
Looks like you may already have answered your own question. =) None-the-less, I hope this helps shed some more light on the subject.
Regards,
Matt
Posted by sdb on April 10, 2005, at 16:54:27
In reply to Re: What is wellbutrin (bupropion) pharmacological, posted by mattw84 on April 10, 2005, at 15:24:05
Hi mattw84,
Yes, serotonin plays a major role in the whole body. But in spite of the minor 5% i think it definitaly plays a major role in defined locations of the brain always involved with all other neurotransmitters, receptors. The receptors define the effect not the ligand per se.
I suppose the priapism is likely more caused by the high affinity or even downregulation for alpha1-receptors in arteries in the cavernosus of the penis.
Your state sounds interesting. I have never heard Wellbutrin could be usefull for bp and is effective even in sp.
I think I will give the Wellbutrin a try in a low dosage to see what it does. I have never taken it yet and I am totally unexperienced. But I am anyway pleased to take something different. It seems to be a drug, which can often produce different reactions in individuals. Bupropion is highly metabolized by the liver.
I would be interested in more information, if bupropion works more through dopamine transmission or noradrenaline transmission (I dont like to much central norepinephrine transmission)
Interestingly, if bupropion works in specific locations in dopamine transmission it could lead to abuse.
Thanks for your advice,
sdb
Posted by mattw84 on April 10, 2005, at 23:10:41
In reply to Re: What is wellbutrin (bupropion) pharmacological, posted by sdb on April 10, 2005, at 16:54:27
Sdb,
Glad to know my advice is helping in some way. =)
Yes, bupropion has the potential to be abused -- however it most likely would induce seizures and be a rather unpleasant experience, but not unheard of. It is not scheduled by the DEA, yet the following is found in the monograph:
***************************************************************************
The potential for abuse or misuse of bupropion is unclear, but most evidence to date suggests that the potential is low. On several scales measuring feelings of euphoria and drug desirability, there was limited evidence of abuse potential. There also was some evidence of stimulant effects in clinical studies. However, findings from clinical studies are not known to reliably predict the abuse potential of drugs. Although the potential for abuse of bupropion is likely to be low, possible development of dependence on the drug should be considered in deciding whether to use it as an adjunct in smoking cessation in individual patients.
Some increase in motor activity and agitation or excitement occurred in clinical studies in healthy individuals, patients with depression, and individuals with a history of multiple-drug abuse. Based on single-dose studies, bupropion when dosed and administered as recommended is unlikely to be especially reinforcing to abusers of amphetamines or other stimulants, although such individuals may find higher than recommended doses, which were not studied because of seizure risk, to be modestly attractive. No evidence of psychostimulation was observed with single bupropion hydrochloride doses of up to 200 mg as determined by auditory vigilance and visual analog testing.
In multiple-drug abusers who received a single dose of bupropion, dextroamphetamine, or placebo, 400 mg of bupropion hydrochloride produced mild amphetamine-like activity (e.g., feelings of activation, general feelings of well-being) as indicated by a measure of general euphoria in the morphine-benzedrine group subscale of the Addiction Research Center Inventory (ARCI). In addition, these individuals rated 400 mg of bupropion hydrochloride with a score intermediate between those of placebo and the amphetamine on a measure of the drug desirability on the Liking Scale of the ARCI.
Bupropion has been shown to exhibit dose-related CNS-stimulant effects. In animals, some pharmacologic effects common to cerebral stimulants were manifested with the drug, including increases in locomotor activity and the production of a mild stereotyped behavior as well as increases in the rates of responding in several schedule-controlled behavior paradigms. In addition, drug discrimination studies in rats showed stimulus generalization between abusable psychostimulants (e.g., amphetamine, cocaine) and bupropion at high doses.Rhesus monkeys were shown to self-administer IV bupropion.
Copyright © 1994-2005 by Medscape.
***************************************************************************At any rate -- best of luck with the trial! You should know with 8 to 10 days if it agrees with you or not, but if no serious side-effects at that point you might want to continue as most will diminish with time.
Regards,
Matt
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