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This is an old revision of this page, as edited by 207.61.84.162 (talk) at 16:31, 3 September 2006. The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Withdrawl effects:

I have one question: how do you differentiate withdrawl effects due to addiction from withdrawl due to "the results of the brain attempting to reach neurochemical stability." I would argue all withdrawl effects are the result of the the brain and body attempting to re-attain homeostasis. For example, caffeine blocks adenosine. When you stop taking caffeine, you become hyper sensitive to adenosine, and the results are withdrawl. As your body re-attains homeostasis, the withdrawl symptoms go away. So what's the difference?

- Yeah, there is no difference between "brain attempting to reach neurochemical stability" and "addiction." People simply don't want to take something that is physically addictive so the companies get creative in their wording. see physical dependency. I vote this be changed to reflect that it is in fact, physically addictive.


any experience with these drugs?

If you have a specific question about this drug, you might consult the Wikipedia:Reference desk. --David Iberri | Talk 22:44, Apr 19, 2005 (UTC)


At medium dosages, venlafaxine blocks the reuptake of norepinephrine as well as serotonin. At about 225 mg/day, venlafaxine blocks the reuptake of serotonin and norepinephrine

Are these two sentences saying the same thing? Ubermonkey 22:33, 22 September 2005 (UTC)[reply]


I've been under the impression that one of the common reasons for discontinuation of Venlafaxine in women is anorgasma, caused by delay in the sexual response system. Perhaps this should be listed under common side effects. -Cameron Van Sant 9:11, 12 November 2005 (UTC)

Are we documenting your "impression", which would be original research, or are we going to cite hard figures, for which supportive data would be necessary? JFW | T@lk 00:30, 13 November 2005 (UTC)[reply]

Severe discontinuation symptoms

I have commented out this sentence which has to go unless someone comes up with a Wyeth reference for severe discontinuation syndrome:

Wyeth-Ayerst refers to these severe withdrawal symptoms in its product literature as a "severe discontinuation syndrome".

Please note that this not about the existence of these symptoms but about Wyeth's calling them a "severe discontinuation syndrome". The worst thing I could find in Wyeth's online documentation was: "While these events are generally self-limiting, there have been reports of serious discontinuation symptoms" (see Effexor info for healthcare professionals (USA only)). AvB ÷ talk 13:30, 21 January 2006 (UTC)[reply]

I've removed this sentence. AvB ÷ talk 19:37, 29 May 2006 (UTC)[reply]

Discontinuation of this medication sucks. I get the brain shivers even after missing one dose.--K8TEK 23:12, 20 April 2006 (UTC)[reply]

Yes, some people are very susceptible to the side effects of this drug. Then again, I seem to recall reading somewhere that the same people also benefit the most from its therapeutic effects. I hope it works for you. Anyway, it's important that patients know the possible advantages and disadvantages when choosing a medication. AvB ÷ talk 19:37, 29 May 2006 (UTC)[reply]
One of the major problems about this drug is the way in which many physicians have been prescribing it without warning patients of the seriousness of side effects or the fact that withdrawal effects are MAJOR -- NOT A JOKE. If you want to get an idea of the impact of this drug on patients, look at the Effexor Petition website and just scan the more than 10,000 comments. I wish that some of these doctors would try the drug themselves for a few months. Unfortunately, the drug firms do not promote side effects. The trend now is for drug companies to shift responsibility onto doctors as the warnings are now unmistakable and if a physician failed to advise a patient properly, they could potentially be sued for malpractice. It is moving in that direction very fast. There are recent histories of how vicious and influential drug companies can be (The Olivieri Case and the David Healy case - both in Toronto involving drug firms, the university and clinical institutions).

someone removed the link i had placed to the Effexor Petition. There is no reason why this should be removed. This is an honest website with 11,000 signatories, most describing their experiences with this drug. This is an important element of patients saying what happened to them and it should remain here so those who look up this entry can see this perspective. This should not be removed again please without any explanation. I will replace it if it is removed again.. and no one needs to have an editing war. If you have a reason why, state it. We are not in a dictatorship where information is screened by the "truth police".. There is tons of information on side effects, but the petition site is one of the few in which patients tell of their experiences,, THOUSANDS OF PEOPLE.

There is an organized gang of vandals systematically removing all negative drug-related information from Wikipedia. I suggest you put that link back. Someone has hired a PR firm to systematically purge all negative drug information from Wikipedia.

I ;put the link back and someone has removed it again.. STOP THIS NONSENSE... THAT IS NEARLY 12,000 EFFEXOR USERS WHO DESERVE TO BE RECOGNIZED AND WHOSE EXPERIENCE DESERVES TO BE HERE... STOP REMOVING THE LINK WHOEVER IS DOING THIS...... 12,000 PEOPLE AGAINST ONE... WHOEVER IS REMOVING THE LINK.....

Lawsuit

Filed in 2004 due to the discontinuation of the drug side effects. www.effexorwar.com which leads to http://www.pcalawfirm.com/


Effexor and Effexor XR

Does anyone know the difference between Effexor and Effexor XR? I have looked extensively on the web and there are two ideas regarding the difference. the first being that it is slightly different formulation. The second is that it is a controlled released drug. Meaning that the drug is absorbed over a longer period of time supposidly giving less side effects. I can not find anything from Wyeth. Any help on this would be much appreciated. --benjaminevans82 July 2006

I take Effexor XR. My pharmacist said that the main difference between the two was that XR lasts about two hours longer. -- ajk1962f-wikipedia(at)yahoo.com
  • Yes, XR is extended release. The non-XR version of Effexor must be taken several times daily, whereas the XR version, which is in a capsule, can be taken only once a day.

Mechanism of Action

From the article:

"At low and medium dosages, venlafaxine inhibits serotonin reuptake alone, similarly to a selective serotonin reuptake inhibitor (SSRI). At higher dosages (from about 225 mg/day), venlafaxine inhibits the reuptake of norepinephrine as well as serotonin. At high dosages (starting around 300 mg/day), it inhibits dopamine reuptake in addition to serotonin and norepinephrine."

Would it be possible to get this subtantiated? I see the claim repeated multiple times on various web sites, but never with proper citations. --Supergloom 17:45, 20 July 2006 (UTC)[reply]

"Preclinical studies have shown that venlafaxine and its active metabolite, O-desmethylvenlafaxine (ODV), are potent inhibitors of neuronal serotonin and norepinephrine reuptake and weak inhibitors of dopamine reuptake."

I have also noted how several web sites claim that venlafaxine affects diffrent neurotransmitters depending on the dosage.I'm almost certain this is not the case however.

I agree with you. Clearly venlafaxine is an SNRI and has effects on both norepi and serotonin at all dosages. There may be some dopamine effects at all dosages, but psychologically useful changes in dopamine reuptake require higher dosages. If you give enough of a weak reuptake inhibitor to a patient, the effect will be stronger, so it's dose-dependent in that sense. Based upon the prescribing information, it's implied that there are at least *some* dopamine effects, otherwise they wouldn't mention it. It also seems to be the prevailing wisdom among psychiatrists that high doses (such as 225-300mg/day) cause significant effects on dopamine, whereas lower doses do not. Aside from that, I don't think the amount of dopamine reuptake in low vs. high levels of venlafaxine has been quantified, but I would expect higher doses of the drug to cause more dopamine reuptake inhibition, as would be expected with any drug and its effects. See the section I wrote under "Neurotransmitter Effects" for more info. ZZYZX 10:52, 31 August 2006 (UTC)[reply]

Neurotransmitter Effects

Someone asked me via my talk page about venlafaxine dose and how it relates to neurotransmitter levels. He wasn't a registered user, and I'm not even sure this is the article he's referring to, however, here is his question and my response:

Hello! Could you cite the source of your inbformation concearning venlafaxine's dose-dependant effects on serotonin and noradrenaline.I can't find any reliable information to support the claim that noradrenaline reuptake only occurs at medium to high dosages. Also, Wyeth's information on the pharmacodynamics of venlafaxine state that it's a potent inhibitor of both serotonin and noradrenaline and a weak inhibitor of dopamine reuptake.Thank you in advance and please excuse my poor English.
-Thomas
I'm not sure which article you're referring to, so I can't put the source in myself, but the information is part of the official prescribing information for Effexor (venlafaxine HCL) that was released by the manufacturer (Wyeth). The statements can be found in the section "Clinical Pharmacology." The manufacturer's site only had PDFs, but this page (www.rxlist.com - Clinical Pharmacology of Effexor) has the info:
http://www.rxlist.com/cgi/generic4/effexor_cp.htm
It (and official prescribing information) include this statement:
Preclinical studies have shown that venlafaxine and its active metabolite, O-desmethylvenlafaxine (ODV), are potent inhibitors of neuronal serotonin and norepinephrine reuptake and weak inhibitors of dopamine reuptake.
Noradrenaline and norepinephrine are the same thing, but the word "norepinephrine" is used more commonly when it comes to brain chemistry. Incidentally, the same thing is true with adrenaline and epinephrine (i.e. they are the same chemical). I think I wrote (if not then I should have) that serotonin and norepinephrine reuptake are altered at all doses, but dopamine reuptake is only significantly altered with higher doses. Venlafaxine is therefore considered an SNRI (serotonin/norepinephrine reuptake inhibitor), though all three neurotransmitters are effected in a dose-dependent manner. Let me know if you need more info.

Feel free to contact me via my talk page if you need more info. ZZYZX 10:38, 31 August 2006 (UTC)[reply]

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