Antidepressant medications improve irritable bowel syndrome symptoms

Canadian researchers have found that antidepressants might improve symptoms of Irritable bowel syndrome. The symptoms have been published in Canadian Family Physician.

Up to 5 million Canadian adults might have symptoms compatible with IBS. Canadian guidelines recommend TCAs or SSRIs irrespective of whether patients have depression or anxiety.

The researchers carried out systematic reviews and meta-analysis that included 18 RCTs of 1127 adult patients (42% to 100% women); the IBS subtype was usually not specified. Patient-reported outcomes are presented where available.1- Twelve RCTs of TCAs (787 patients) studied amitriptyline, imipramine, desipramine, trimipramine, doxepin, and nortriptyline versus placebo over 6 to 12 weeks.— Global IBS symptom improvement was 57% for TCAs versus 36% for placebo (number needed to treat [NNT] of 5).— Abdominal pain improvement was 59% for TCAs versus 28% for placebo (NNT = 4).— Adverse events (mostly drowsiness and dry mouth) were 36% for TCAs versus 20% for placebo (number needed to harm of 7).- Seven RCTs of SSRIs (356 patients) studied fluoxetine, paroxetine, and citalopram over 6 to 12 weeks.— Global IBS symptom improvement was 55% for SSRIs versus 33% for placebo (NNT = 5).— Abdominal pain improvement was 45% for SSRIs versus 26% for placebo (not statistically different).— Adverse events were 37% for SSRIs versus 27% for placebo (not statistically different).- Evidence was limited by small sample sizes, short study duration, and likely publication bias. Adverse events were not reported in all studies. Older systematic reviews show similar results.

The researchers found that both tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs) might improve overall IBS symptoms. About 55% of patients treated with TCAs or SSRIs will benefit compared with about 35% with placebo. Only TCAs improved abdominal pain for about 60% of patients compared with about 30% with placebo. Studies of TCAs reported more side effects including drowsiness and dry mouth than studies of SSRIs did.  The choice of antidepressant and dosing can be based on potential side effects. Consider TCAs for diarrhea-predominant IBS and give at night (owing to constipating and sedation effects). Consider SSRIs for constipation-predominant IBS and give during the day. Doses varied in the studies; starting low and increasing slowly based on response seems reasonable.