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Ford AC, Wright-Hughes A, Alderson SL, et al. Amitriptyline at Low-Dose and Titrated for Irritable Bowel Syndrome as Second-Line Treatment in primary care (ATLANTIS): a randomised, double-blind, placebo-controlled, phase 3 trial. Lancet. 2023;402(10414):1773-1785. PMID 37858323

One-paragraph summary

Four hundred and sixty-three adults with Rome IV IBS of any subtype and continuing symptoms (IBS-SSS ≥75) despite dietary change and first-line therapy were recruited at 55 general practices in Wessex, the West of England and West Yorkshire between 18 October 2019 and 11 April 2022, and randomised 1:1 to amitriptyline 10 mg once daily — self-titrated by the patient over three weeks to a maximum of 30 mg — or matched placebo for six months. Mean age was 48.5 years (SD 16.1); 315 (68%) were women. Participants, their GPs, investigators and the analysis team were all masked. The intention-to-treat difference in IBS-SSS at six months favoured amitriptyline by −27.0 points (95% CI −46.9 to −7.10; p=0.0079), and subjective global assessment of relief favoured amitriptyline with OR 1.78 (1.19–2.66; p=0.005). Forty-six participants (20%) discontinued amitriptyline (30, 13%, for adverse events) against 59 (26%) discontinuing placebo (20, 9%, for adverse events). There were five serious adverse reactions (two amitriptyline, three placebo). The trial is registered ISRCTN48075063; the full Health Technology Assessment report is Wright-Hughes 2024 (PMID 39397570).

Key findings

  • Primary outcome IBS-SSS at 6 months: −27.0 (−46.9 to −7.10), p=0.0079 — the largest tricyclic trial ever conducted in IBS, by the authors' own statement.
  • Key secondary, subjective global assessment of relief at 6 months: OR 1.78 (1.19–2.66), p=0.005.
  • No effect on somatoform symptom reporting, anxiety, depression, or work and social adjustment scores (Wright-Hughes 2024, PMID 39397570) — the gut effect is not mediated by a mood effect.
  • Adverse-event trial withdrawals 12.9% amitriptyline vs 8.7% placebo; most adverse events mild.
  • Patient-led self-titration was feasible and, in the nested qualitative study of 77 interviews with 42 participants and 16 GPs, described as acceptable and empowering.
  • Post-hoc analyses found quantitatively larger effects in those aged ≥50 (IBS-SSS mean difference −46.5, −74.2 to −18.8), in the 70% most deprived areas of England (≥30% pain improvement OR 2.70, 1.52–4.77), in men, in those with higher PHQ-12 scores and in IBS-D (Wright-Hughes 2025, PMID 39863398).

Limitations

  • The primary effect of −27.0 points falls short of the trial's own prespecified 35-point minimum clinically important difference, while the responder secondary is clearly positive. The trial reports this tension rather than resolving it.
  • Six-month primary endpoint with blinded extension to 12 months; nothing longer in a lifelong relapsing condition.
  • 68% female, UK primary care only; generalisability outside NHS general practice is untested.
  • The subgroup findings are exploratory and unreplicated, including the unusual socioeconomic-deprivation interaction.
  • Placebo-arm discontinuation was higher than active-arm discontinuation overall (26% vs 20%), which complicates simple tolerability comparisons.

Why it matters

Before ATLANTIS, tricyclics in IBS rested on small, old, mostly secondary-care trials, and NICE's suggestion to use them second-line in primary care was untested in that setting — GPs accordingly prescribed them rarely. ATLANTIS tested the guidance where the guidance applies, with patient-led titration and full masking, and found it works. It is the strongest single piece of evidence for any drug in IBS delivered in the setting where most IBS is managed, and it reframes amitriptyline as a gut–brain neuromodulator at doses far below antidepressant dosing — a reframing the trial's own null mood results support. Its investigators' request for materials "to distinguish amitriptyline for irritable bowel syndrome from use as an antidepressant" also makes it a document about stigma as a barrier to treatment.

Cited by wiki pages

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