#229 Antispasmodics and peppermint oil: Old news or a breath of fresh air in managing Irritable Bowel Syndrome

CLINICAL QUESTION

QUESTION CLINIQUE

Are antispasmodics (including peppermint oil) effective in treating irritable bowel syndrome symptoms?

BOTTOM LINE

RÉSULTAT FINAL

Approximately 60% of patients report overall symptom or abdominal pain "improvement" on antispasmodics (including peppermint oil), compared to ~30-50% on placebo, with numbers needs to treat of 3-8.  Compared to placebo, adverse events occur for an additional 1 in 20 with antispasmodics and 1 in 11 on peppermint oil.

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EVIDENCE

DONNÉES PROBANTES

3 Systematic Reviews:

29 randomized controlled trials (RCTs), 2333 patients, various antispasmodics, including peppermint oil.¹ Patient reported outcomes after 1 week to 6 months:
- Overall "symptom improvement": 57% versus 39% placebo; number needed to treat (NNT)=6.
- Abdominal pain "improvement": 58% versus 46% placebo; NNT=8
Older systematic review (13 RCTs, 1379 patients). Outcomes at 2 weeks-6 months similar.² Adverse events (dry mouth, dizziness, blurred vision reported):
- 14% versus 9% placebo; number needed to harm (NNH)=20.
Systematic review of peppermint oil alone (9 RCTs, 726 patients, 2-12 weeks duration).³
- Overall "symptom improvement": 69 versus 31% placebo; NNT=3.
- Abdominal pain "improvement": 57% versus 27% placebo; NNT=4.
- Overall adverse events (including heartburn, dry mouth, peppermint smell/taste):
  - 22% versus 13% placebo; NNH=11.

Newest RCTs:

712 patients randomized to hyoscine, hyoscine + acetaminophen, acetaminophen, or placebo for four weeks.⁴ Paper translated by TFP authors.
- "Slight" or "significant" symptom improvement: hyoscine + acetaminophen=81%, hyoscine=76%, acetaminophen=72%, placebo=64%;
  - Hyoscine groups statistically better than placebo.
- Adverse events: 5% overall.
427 patients given pinaverium 50mg or placebo TID.⁵ After 4 weeks:
- >30% improvement in abdominal pain: 62% versus 30% placebo; NNT=3.
72 patients given peppermint oil tablets or placebo.⁶ After 4 weeks:
- Mean reduction 4-point symptom score: ~1.2 peppermint oil versus 0.7 placebo.

Limitations: small studies,^1,2 short durations,1 multiple/incomplete outcomes reported^1,4, conflicts of interest/industry funding^3,6, use of non-validated scales.⁶ Context:

Large placebo response often seen in IBS studies.⁷
Guidelines recommend considering antispasmodics^8,9 or peppermint oil⁸ in IBS patients.
Antispasmodics in Canada include hyoscine, pinaverium, trimebutine, dicycloverine, peppermint oil.
- Cost varies significantly
  - Peppermint oil ranges ~$60 to $360 for 3 months.¹⁰