title: Lubiprostone does not influence visceral pain thresholds in patients with irritable bowel syndrome.
abstract: BACKGROUND
  In clinical trials, lubiprostone reduced the severity of abdominal pain. The primary aim was to determine whether lubiprostone raises the threshold for abdominal pain induced by intraluminal balloon distention. A secondary aim was to determine whether changes in pain sensitivity influence clinical pain independently of changes in transit time.
  
  
  METHODS
  Sixty-two patients with irritable bowel syndrome with constipation (IBS-C) participated in an 8-week cross-over study. All subjects completed a 14-day baseline ending with a barostat test of pain and urge sensory thresholds. Half, randomly selected, then received 48 μg day(-1) of lubiprostone for 14 days ending with a pain sensitivity test and a Sitzmark test of transit time. This was followed by a 14-day washout and then a crossover to 14 days of placebo with tests of pain sensitivity and transit time. The other half of the subjects received placebo before lubiprostone. All kept symptom diaries.
  
  
  RESULTS
  Stools were significantly softer when taking lubiprostone compared to placebo (Bristol Stool scores 4.20 vs 3.44, P < 0.001). However, thresholds for pain (17.36 vs 17.83 mmHg, lubiprostone vs placebo) and urgency to defecate (14.14 vs 14.53 mmHg) were not affected by lubiprostone. Transit time was not significantly different between lubiprostone and placebo (51.27 vs 51.81 h), and neither pain sensitivity nor transit time was a significant predictor of clinical pain.
  
  
  CONCLUSIONS
  Lubiprostone has no effect on visceral sensory thresholds. The reductions in clinical pain that occur while taking lubiprostone appear to be secondary to changes in stool consistency.
authors.affiliation: Center for Functional Gastrointestinal and Motility Disorders and Division of Gastroenterology and Hepatology, University of North Carolina at Chapel Hill, NC 27599, USA. william_whitehead@med.unc.edu
authors.forename: W E
authors.initials: WE
authors.lastname: Whitehead
authors.forename: O S
authors.initials: OS
authors.lastname: Palsson
authors.forename: L
authors.initials: L
authors.lastname: Gangarosa
authors.forename: M
authors.initials: M
authors.lastname: Turner
authors.forename: J
authors.initials: J
authors.lastname: Tucker
mesh_terms: D000328:Adult; D000527:Alprostadil / Q000031:analogs & derivatives* / Q000627:therapeutic use; D018592:Cross-Over Studies; D003672:Defecation / Q000187:drug effects; D004106:Dilatation; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000150:complications / Q000188:drug therapy*; D000068238:Lubiprostone; D008297:Male; D010146:Pain / Q000188:drug therapy* / Q000209:etiology; D017288:Pain Threshold / Q000187:drug effects
chemical_list: D000068238:Lubiprostone; D000527:Alprostadil