Background: Venlafaxine hydrochloride, a structurally novel antidepressant, is also the first nontricyclic serotonin/norepinephrine reuptake inhibitor. Although venlafaxine has an overall side effect and safety profile that is comparable to other newer antidepressants, it can cause both transient and sustained elevations of supine diastolic blood pressure (SDBP), probably the result of noradrenergic potentiation.
Method: Presented here is a meta-analysis of original data on blood pressure, using both random effects and a multivariate survival analyses. The sample consisted of 3744 patients with major depression who were studied in controlled clinical trials comparing venlafaxine with imipramine and/or placebo. Patients were treated for 6 weeks of acute phase therapy; some responders received up to 1 year of continuation phase therapy.
Results: Venlafaxine and imipramine were associated with small, but statistically significant, increases in SDBP during acute phase therapy. When compared with imipramine and placebo, venlafaxine was also associated with a greater proportion of persistent elevations of SDBP during continuation therapy. The effect of venlafaxine was highly dose dependent, and the incidence of elevated SDBP was statistically and clinically significant only at dosages above 300 mg/day. Venlafaxine did not adversely affect the control of blood pressure for patients with preexisting high blood pressure or elevated baseline values.
Conclusion: Venlafaxine has a dose-dependent effect on SDBP that is clinically significant at high dosages. Concern about blood pressure effects should not deter first-line use of this effective antidepressant, although more extensive studies of patients with cardiovascular diseases are still necessary.