Venlafaxine management

A number of non-hormonal therapies have been studied for symptomatic management of vasomotor symptoms, including antidepressants [e.g., selective serotonin reuptake inhibitors (SSRIs) and venlafaxine], herbal products (e.g., soy, black cohosh, and dong quai), and a group of miscellaneous agents (e.g., gabapentin, clonidine, and megestrol). The choice of therapy depends on the patient s concomitant disease states, such as depression and hypertension, and the risk for potential adverse effects. 

When starting a SSRI, the abrupt increase in serotonin may cause side effects. In the brain, the short-term effects include headache, sleep disturbance, nervousness, anxiety, and tremulousness. The digestive system effects include nausea, loose stools, decreased appetite, and indigestion. Most of these effects are mild and shortlived or can be managed with over-the-counter remedies. Nausea, for example, can be minimized by taking a SSRI after meals. These effects are also commonly seen with venlafaxine and duloxetine, atypical antidepressants that block serotonin reuptake like the SSRIs. 

Drugs that potentiate serotonin function can cause ejaculatory delay in men, and this has led to the use of SSRIs to treat premature ejaculation (SEDA-26, 13). Venlafaxine is also reported to cause problems with ejaculation during routine use and its efficacy has been studied in a placebo-controlled, crossover study in 31 men with ejaculation latencies of less than 2 minutes (25). Both placebo and venlafaxine (75 mg/day of the XL formulation) significantly increased latency to ejaculation over baseline, placebo by 2 minutes and venlafaxine by 3 minutes there was no difference between the two treatments. The authors concluded that venlafaxine is not effective for the management of premature ejaculation. However, the small number of subjects studied and the large placebo effect makes this conclusion tentative. It does appear, however, that the effect of venlafaxine on ejaculation delay is probably less striking than, for example, that of paroxetine. 

The authors suggested that the effect of venlafaxine on cardiac conduction is mediated by its ability to block the fast inward sodium current in cardiac myocytes. This might promote membrane stabilizing effects in a similar way to tricyclic antidepressants. They recommended that the management of venlafaxine overdose should include cardiac monitoring. 

Because 25% of patients will stop SSRIs due to side effects and an additional 30% to 40% will fail to achieve a therapeutic response, other antidepressant alternatives are of great importance. Venlafaxine is a dual-action antidepressant that enhances serotonin activity at low doses and norepinephrine at higher doses. Preliminary evidence suggests that these multiple actions on neurotransmitters may confer therapeutic superiority over SSRIs for the management of severe or melancholic depression, but the risk of HTN with high-dose venlafaxine should not be overlooked. 

Loprinzi CL, Kugler JW, Sloan JA, et al. Venlafaxine in management of hot flashes in survivors of breast cancer A randomized, controlled trial. Lancet 2000 356 2059-2063. 

C. L. Loprinzi, et al., Venlafaxine in Management of Hot Flashes in Survivors of Breast Cancer A Randomized Controlled Trial, Lancet 356 (2000) 2059-2063. 

---