Design: Systematic review and meta-analysis of RCTs (GRADE)
Population: Adults with chronic idiopathic constipation or IBS-C
Primary outcome: Change in complete spontaneous bowel movements per week
Effect: MD +0.75 to +1.00 CSBMs/week across doses; diarrhoea the main AE

This meta-analysis pooled randomised placebo-controlled trials of plecanatide, a guanylate cyclase-C agonist, in chronic idiopathic constipation and irritable bowel syndrome with constipation, searched to August 2025.

Plecanatide increased complete spontaneous bowel movements at every dose studied, by about 0.75 to 1.0 per week over placebo, with the largest effect at 9 mg. Spontaneous bowel movements rose by about 1.0 to 1.6 per week at 1–6 mg. Stool consistency, abdominal pain and bloating improved mainly at 3–6 mg. Diarrhoea was the commonest adverse effect and the main reason for stopping, and rose with dose; other safety outcomes did not differ. The authors judged 3 mg the best balance.

The gains are modest — around one extra complete bowel movement a week — and the trials were largely industry funded. Plecanatide's availability in India is uncertain; the same class includes linaclotide.

Optimise fibre, fluids and osmotic laxatives before second-line secretagogues in chronic constipation.
Expect about one extra complete bowel movement a week from plecanatide over placebo.
Warn patients that diarrhoea is the main side effect and rises with dose.
Check for alarm features — weight loss, bleeding, anaemia, new onset after 50 — before treating as functional constipation.

Why it matters

It sets realistic expectations for a second-line class: modest, consistent benefit with a dose-limiting side effect.

The statistics, in plain English

A mean difference of about 1 complete bowel movement per week is statistically clear but modest in size; whether it matters depends on how troublesome the patient's constipation is.