SNRI — Serotonin-Norepinephrine Reuptake Inhibitors

SNRIs are a class of antidepressants that act on two systems: they block the reuptake of both serotonin and norepinephrine, combining the effects of antidepressants with those of some noradrenergic agents. This dual action can be advantageous in cases involving fatigue, chronic pain, or when an SSRI alone hasn't been enough.

Commonly prescribed SNRIs include: venlafaxine (Effexor — available in extended-release capsules), desvenlafaxine (Pristiq — the active metabolite of venlafaxine), and duloxetine (Cymbalta — also approved for fibromyalgia and neuropathic pain).

Compared with SSRIs, SNRIs have similar efficacy for depression but may be preferred when there is: associated chronic pain (duloxetine especially), prominent fatigue, or a prior failed trial of an SSRI. The side-effect profile is similar to SSRIs, with the addition of increased blood pressure at higher doses (especially with venlafaxine). Discontinuation should be gradual — stopping abruptly can cause discontinuation syndrome.