Melatonin for the treatment of irritable bowel syndrome

Table 1 Placebo-controlled studies: treatment effect of melatonin in irritable bowel syndrome patients

Ref.	Subjects (total, age, IBS Criteria)	IBS subtypes	Treatment vs control	Pain	Bloating/distention	Motility	Sleep	Psycho-logical	Overall IBS score	Outcome
Song et al[63], 2005, Singapore	40, 20-64 years old, ROME II IBS (with sleep disturbance)	14 IBS-C, 18 IBS-D, 8 IBS-A	20 (3 mg, bedtime, 2 wk) vs 20 Placebo	Yes4	No	No	No	No	N/A	Decreased abdominal pain and increased pain threshold
Lu et al[26], 2005, Singapore	17, 41+/-14 years old woman, ROME II IBS	N/A	12 (3 mg bedtime for 8 wk) vs 12 Placebo	Yes5	Yes5	No1	No	No	N/A	Effective in improving bowel symptoms in female IBS patients
Saha et al[27], 2007, India	18, 18-65 years old, ROME II IBS	N/A	9 (3 mg bedtime for 8 wk) vs 9 Placebo	Yes	Yes	Yes	N/A	Yes	Yes2	Improved overall IBS score, extracolonic score as well as QOL
Chojnacki et al[72], 2013, Poland	80, 48-65 years old woman, ROME III IBS	40 IBS-C, 40 IBS-D	40 (3 mg morning, 5 mg bedtime for 6 mo) vs 40 placebo	N/A	N/A	Yes3	N/A	N/A	Yes3	Improved visceral pain and abdominal bloating for IBS-C patients

¹CTT significantly prolonged in control subjects. Only a trend of prolonging CTT in IBS patients;

²Improved overall IBS score (45% vs 16.66%, P < 0.05);

³Significant result only for IBS-C, the intensity of visceral pain and abdominal bloating had decreased in 70% of patients (P < 0.01) and constipation in 50% of patients (P < 0.05);

⁴melatonin taken for two weeks significantly decreased mean abdominal pain score (2.35 vs 0.70; P < 0.001) and increased mean rectal pain threshold (8.9 vs 21.2 mmHg; P < 0.001);

⁵The improvement in mean ± SD. IBS symptom score was significantly greater after treatment with melatonin (3.9 ± 2.6) than with placebo therapy (1.3 ± 4.0, P = 0.037 The beneficial effects of melatonin were most marked in symptoms such as abdominal plain, abdominal distension and abnormal sensation of defecation. CTT: Colonic transit time; N/A: Not available; IBS: Irritable bowel syndrome; QOL: Quality of life.

Table 2 Placebo-controlled studies: side effects of melatonin in irritable bowel syndrome patients

Ref.	Subjects (total, age, IBS criteria)	Dosage, frequency, duration	Sleepiness	GI side effect	Others
Lu et al[26], 2005, Singapore	17, 41+/-14 years old woman, ROME II IBS	3 mg bedtime for 8 wk	1 × Daytime sleepiness (both treatment and placebo group)	Nil	Nil
Saha et al[27], 2007, India	18, 18-65 years old, ROME II IBS	3 mg bedtime for 8 wk	1 × Drowsiness (both groups),	Nil	1 decreased libido
Chojnacki et al[72], 2013, Poland	80, 48-65 years old woman, ROME III IBS	3 mg morning, 5 mg bedtime for 6 mo	Nil	Nil	2 fatigue, 1 vertigo

IBS: Irritable bowel syndrome; GI: Gastrointestinal.