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Effexor XR (Venlafaxine) Facts
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Basic information
- Generic name: Venlafaxine hydrochloride
- Brand/Trade names: Effexor, Effexor XR (Extended
Release)
- Dosages:
Tablets: 25 mg, 37.5mg, 50 mg, 75 mg, 100 mg
Capsules, extended-release: 37.5mg, 75 mg, 150 mg
- Pharmacologic category: Serotonin and norepinephrine
reuptake inhibitor (SNRI)
- FDA approved: October 20, 1997
- Manufacturer: Wyeth Pharmaceuticals Inc.
- Habit forming? Not known
- Pregnancy risk factor: C
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Medical uses
Effexor (Venlafaxine hydrochloride), an antidepressant (mood
elevator), is indicated for the treatment of depression, generalized
anxiety disorder, social anxiety disorder (social phobia) and
panic disorder. This medication is sometimes prescribed for other
uses. Effexor blocks the ability of the nerve terminals in the
brain to bind and break down serotonin and norepinephrine so that
more is available for the brain to use. Abnormally low levels
of serotonin and norepinephrine may play a role in conditions
such as depression and anxiety disorders.
The most common Effexor side effects include nausea, dizziness,
insomnia, somnolence, and dry mouth.
Effexor is associated with a very troublesome discontinuation
syndrome. To avoid this syndrome, Effexor (venlafaxine) should
be tapered by reducing the daily dose by no more than 75 mg at
one-week intervals.
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Pharmacological characteristics
- Absorption: Absolute bioavailability is 45% and well
absorbed (at least 92%) of single oral dose. Steady-state concentrations
of venlafaxine and O-desmethylvenlafaxine (ODV) in plasma are
attained within 3 days of oral dose. Exhibits linear kinetics
over dose range 75 to 450mg/day.
- Metabolism: Extensively metabolized in the liver. The
only major metabolite is ODV, which is active.
- Elimination half-life: elimination half-life of venlafaxine
is 5 ± 2 and 11 ± 2 hours of O-desmethylvenlafaxine (ODV)
- Excretion: Renal elimination of venlafaxine and its
metabolite is the primary route of excretion. Approximately
87% of a venlafaxine dose is recovered in the urine within 48
hours as either unchanged venlafaxine (5%), unconjugated ODV
(29%), conjugated ODV (26%), or other minor inactive metabolites
(27%). Renal elimination of venlafaxine and its metabolites
is the primary route of excretion.
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Benefits
- powerful antidepressant
- high therapeutic success rate [4]
- effective in depression, resistant to other antidepressants
[5, 7]
- more effective than fluoxetine and paroxetine for remission
of depressive symptoms [6]
- rapid onset of action [18]
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Concerns
- high rate of nausea and vomiting
- can increase blood pressure
- high rate of severe withdrawal syndrome [3]
- toxicity in overdose (cardiovascular toxicity, rhabdomyolysis)
[19, 20]
- high risk of suicide [21]
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Unlabeled uses
- diabetic neuropathy
- migraine prophylaxis [11]
- hot-flashes
- post-traumatic stress disorder (PTSD) [10]
- fibromyalgia [12]
- tension-type headache [13]
- chronic pain [14]
- polyneuropathy [16]
- premenstrual dysphoric disorder [15]
- attention deficit hyperactivity disorder (ADD/ADHD) [17]
Effexor for fibromyalgia
Some studies have shown that Effexor may be effective for fibromyalgia
treatment - though the drug is not approved for this use [12].
Although it is not entirely clear how Effexor works for fibromyalgia,
the drug may help block the nerve pain signals in the spinal cord
or brain. This may help with the pain caused by fibromyalgia.
The studies have shown that Effexor can provide pain relief and
decrease disability due to fibromyalgia. People taking Effexor
for fibromyalgia also showed improvement in anxiety or depression
symptoms.
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Mechanism of action
Effexor (venlafaxine) blocks the reuptake of serotonin, noradrenaline
and, to a lesser extent, dopamine. Effexor has the flexibility
of being an SSRI at lower doses and an SNRI at higher doses.
Effexor (Venlafaxine) antinociceptive effects
Effexor (venlafaxine) has an analgesic effect that is independent
of its antidepressant activity. The study has shown that antinociceptive
effect of venlafaxine is mainly influenced by the kappa- and delta-opioid
receptor subtypes combined with the alpha2-adrenergic receptor.
These results suggest a potential use of venlafaxine in the management
of some pain syndromes [9].
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Effexor Discussions Boards & Forums
- Effexor (Venlafaxine) reviews and ratings (recommended medication
by 71% of reviewers): http://psychcentral.com/meds/effexor.html
- Effexor discussion: http://www.drugs.com/forum/featured-drugs/effexor-20972.html
- Effexor (Venlafaxine) discussion: http://www.depressionforums.org/forums/index.php?showforum=54
- Effexor, Venlafaxine Forum: http://www.topix.net/forum/drug/effexor
- Effexor withdrawal boards
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Reliable Sources for Information about Effexor
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References
- 1. U.S. Food and Drug Administration. Effexor (Venlafaxine)
U.S. Prescribing Information. Available at (PDF format): Prescribing
Information
- 2. U.S. Food and Drug Administration. Effexor XR (Venlafaxine
XR) U.S. Prescribing Information. Available at (PDF format):
Prescribing
Information
- 3. Fava M, Mulroy R, Alpert J, Nierenberg AA, Rosenbaum JF.
Emergence of adverse events following discontinuation of treatment
with extended-release venlafaxine. Am J Psychiatry. 1997 Dec;154(12):1760-2.
PubMed
- 4. Einarson TR, Arikian SR, Casciano J, Doyle JJ. Comparison
of extended-release venlafaxine, selective serotonin reuptake
inhibitors, and tricyclic antidepressants in the treatment of
depression: a meta-analysis of randomized controlled trials.
Clin Ther. 1999 Feb;21(2):296-308. PubMed
- 5. Sa'iz-Ruiz J, Iba'nez A, Di'az-Marsa' M, Arias F, Padi'n
J, Marti'n-Carrasco M, Montes JM, Ferrando L, Carrasco JL, Marti'n-Ballesteros
E, Jorda' L, Chamorro L. Efficacy of venlafaxine in major depression
resistant to selective serotonin reuptake inhibitors. Prog Neuropsychopharmacol
Biol Psychiatry. 2002 Oct;26(6):1129-34. PubMed
- 6. Shelton C, Entsuah R, Padmanabhan SK, Vinall PE. Venlafaxine
XR demonstrates higher rates of sustained remission compared
to fluoxetine, paroxetine or placebo. Int Clin Psychopharmacol.
2005 Jul;20(4):233-8. PubMed
- 8. Kaplan EM. Efficacy of venlafaxine in patients with major
depressive disorder who have unsustained or no response to selective
serotonin reuptake inhibitors: an open-label, uncontrolled study.
Clin Ther. 2002 Jul;24(7):1194-200. PubMed
- 9. Schreiber S, Backer MM, Pick CG. The antinociceptive effect
of venlafaxine in mice is mediated through opioid and adrenergic
mechanisms. Neurosci Lett. 1999 Oct 1;273(2):85-8. PubMed
- 10. Pae CU, Lim HK, Ajwani N, Lee C, Patkar AA. Extended-release
formulation of venlafaxine in the treatment of post-traumatic
stress disorder. Expert Rev Neurother. 2007 Jun;7(6):603-15.
PubMed
- 11. Ozyalcin SN, Talu GK, Kiziltan E, Yucel B, Ertas M, Disci
R. The efficacy and safety of venlafaxine in the prophylaxis
of migraine. Headache. 2005 Feb;45(2):144-52. PubMed
- 12. Dwight MM, Arnold LM, O'Brien H, Metzger R, Morris-Park
E, Keck PE Jr. An open clinical trial of venlafaxine treatment
of fibromyalgia. Psychosomatics. 1998 Jan-Feb;39(1):14-7. PubMed
- 13. Zissis NP, Harmoussi S, Vlaikidis N, Mitsikostas D, Thomaidis
T, Georgiadis G, Karageorgiou K. A randomized, double-blind,
placebo-controlled study of venlafaxine XR in out-patients with
tension-type headache. Cephalalgia. 2007 Apr;27(4):315-24. Epub
2007 Mar 7. PubMed
- 14. Taylor K, Rowbotham MC. Venlafaxine hydrochloride and
chronic pain. West J Med. 1996 Sep;165(3):147-8.
- 15. Cohen LS, Soares CN, Lyster A, Cassano P, Brandes M, Leblanc
GA. Efficacy and tolerability of premenstrual use of venlafaxine
(flexible dose) in the treatment of premenstrual dysphoric disorder.
J Clin Psychopharmacol. 2004 Oct;24(5):540-3. PubMed
- 16. Sindrup SH, Bach FW, Madsen C, Gram LF, Jensen TS. Venlafaxine
versus imipramine in painful polyneuropathy: a randomized, controlled
trial. Neurology. 2003 Apr 22;60(8):1284-9. PubMed
- 17. Mukaddes NM, Abali O. Venlafaxine in children and adolescents
with attention deficit hyperactivity disorder. Psychiatry Clin
Neurosci. 2004 Feb;58(1):92-5. PubMed
- 18. Andrews JM, Ninan PT, Nemeroff CB. Venlafaxine: a novel
antidepressant that has a dual mechanism of action. Depression.
1996;4(2):48-56. PubMed
- 19. Howell C, Wilson AD, Waring WS. Cardiovascular toxicity
due to venlafaxine poisoning in adults: a review of 235 consecutive
cases. Br J Clin Pharmacol. 2007 Aug;64(2):192-7. Epub 2007
Feb 12. PubMed
- 20. Pascale P, Oddo M, Pacher P, Augsburger M, Liaudet L.
Severe rhabdomyolysis following venlafaxine overdose. Ther Drug
Monit. 2005 Oct;27(5):562-4. PubMed
- 21. Rubino A, Roskell N, Tennis P, Mines D, Weich S, Andrews
E. Risk of suicide during treatment with venlafaxine, citalopram,
fluoxetine, and dothiepin: retrospective cohort study. BMJ.
2007 Feb 3;334(7587):242. Epub 2006 Dec 12. PubMed
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Interesting Effexor facts
- Effexor (venlafaxine) is a representative of a new class of antidepressants
(SNRIs) which inhibit selectively the uptake of serotonin and noradrenaline,
but in contrast to tricyclics, show no affinity for neurotransmitter
receptors.
- Effexor XR is a once-daily SNRI approved for the treatment of
depression, generalized anxiety disorder (GAD), and social anxiety
disorder that has been proven effective.
- It was first introduced by Wyeth in 1993. A generic will not
be available to U.S. citizens until 2008.
- Sometimes, this medication is prescribed "off label" for diabetic
neuropathy in a similar manner to duloxetine.
- Nausea is the most commonly reported side effect. This will usually
diminish within two weeks.
- Effexor has a good remission rate for depression that resisted
other antidepressant medication.
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