A randomized, double-blind, placebo-controlled trial of polyethylene glycol effects on fasting and postprandial rectal sensitivity and symptoms in hypersensitive constipation-predominant irritable bowel syndrome.
OBJECTIVE
To assess the effect of polyethylene glycol 3350 (PEG) on fasting and postprandial (PP) perception of rectal distension and symptoms in hypersensitive constipation-predominant irritable bowel syndrome (IBS-C).


METHODS
Forty-two patients meeting Rome II criteria for IBS-C and with a pain threshold of < 32 mmHg were included in a randomized, double-blind, placebo-controlled trial. Patients received either oral PEG, 3.45 g t.i.d. orally for 30 days or placebo. Rectal sensitivity was assessed before and after treatment with a barostat using the ascending method of limits, during basal and PP periods.


RESULTS
No changes in fasting and PP rectal tone and thresholds for first sensation, gas sensation, urge to defecate, and pain was observed with PEG in relation to placebo. In both groups, pressure at which patients crossed the thresholds for noxious (PEG: from 28 ± 8.8 to 22 ± 6.9 mmHg) and non noxious (PEG: from 16 ± 4.9 to 12 ± 3.6 mmHg) stimuli decreased compared with pretreatment values. PEG improved consistency of faeces and showed a trend to diminish blood in faeces. PEG and placebo increased bowel movements per week (P < 0.001), and relieved symptoms without significant side-effects.


CONCLUSIONS
Both PEG 3350 and placebo were clinically useful in patients with IBS-C, an effect that cannot be explained by changes in rectal tone and sensation. The results support the concept that visceral sensitivity is not stable and has a heterogeneous response to drugs, and suggest the existence of a post healing hypersensitivity state.
Awad
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RA
Gastroenterology service U-107, Mexico city General Hospital, Mexico City, Mexico. awadrichard@iserve.net.mx
Camacho
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S
D000328:Adult; D003248:Constipation / Q000150:complications / Q000188:drug therapy*; D003672:Defecation / Q000187:drug effects; D004311:Double-Blind Method; D005215:Fasting / Q000502:physiology; D005243:Feces; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000150:complications / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011092:Polyethylene Glycols / Q000494:pharmacology / Q000627:therapeutic use*; D019518:Postprandial Period / Q000502:physiology; D012007:Rectum / Q000187:drug effects / Q000503:physiopathology*; D012677:Sensation / Q000187:drug effects; D012684:Sensory Thresholds; D018709:Statistics, Nonparametric; D013501:Surface-Active Agents / Q000494:pharmacology / Q000627:therapeutic use*; D055815:Young Adult
D013501:Surface-Active Agents; D011092:Polyethylene Glycols