Hi Christine and Hannah,
I dug deeper into the pharmacolgy of effexor and this is the story: the drug is a racemic mixture or “racemate”. Basically it is composed of two similar but different molecules called stereoisomers –– one left-handed and the other right-handed. Think of your hands as the molecules. They are nearly identical but mirror images of each other so not quite identical. In Effexor one of the molecules has a greater effect on noradrenalin reuptake while the other molecule is more potent for serotonin reuptake. Both of them combined have a greater overall effect on serotonin than on noradrenalin.
Based on the above, any dose of effexor has an effect on both serotonin and noradrenalin but with a slightly greater effect on serotonin reuptake. Of course as the dose gets higher, so too does the total reuptake potential on both serotonin and noradrenalin.
Christine - while all of the SSRI type meds do the same thing – prevent serotonin reuptake – they are all different molecules and therfore have slightly different overall effects on how you feel, migraine-killing potential and so on.
Hannah - I suspect that you could have had a bad time any one of the other SSRIs too and I would not necessarily attribute this bad effect to effexor per se. It is equally also possible that another SNRI or SSRI would not cause such a bad reaction or even work! Cymbalta, for example, is apparently not very good for migraine control yet is an SNRI and has a much stronger effect on noradrenalin than effexor. Makes no sense apart from the fact that the active molecules are different.
[size=130]This about effexor withdrawal:[/size]
Symptoms reported included agitation, anorexia, anxiety, confusion, dry mouth, fatigue, paraesthesiae, vertigo, hypomania, nausea, vomiting, dizziness, convulsion, headache, diarrhoea, sleep disturbance, insomnia, somnolence, sweating and nervousness. Where such symptoms occurred, they were usually self limiting, but in a few patients lasted for several weeks.
Discontinuation effects were systematically studied in a long-term fixed dose trial for generalised anxiety disorder; 24 and 11% of patients recorded the appearance of at least three withdrawal symptoms on abrupt discontinuation from venlafaxine 150 or 75 mg once daily, respectively, compared with 3% for placebo. The most commonly reported withdrawal symptoms on abrupt discontinuation were nausea, vomiting, dizziness, lightheadedness and tinnitus from venlafaxine 150 mg once daily and dizziness from venlafaxine 75 mg once daily. Severe withdrawal reactions were observed in 1.3% of patients discontinuing from 75 mg once daily (no patients requiring further drug treatment).
There is also a report of a withdrawal syndrome, confirmed by two challenges in a 32 year old woman who had received venlafaxine 300 mg daily for eight months. It is therefore recommended that the dosage of Effexor-XR be tapered gradually and the patient monitored. The period required for discontinuation may depend on the dose, duration of therapy and the individual patient.
Scott 8)