The physical properties of rectal contents have effects on anorectal continence: insights from a study into the cause of fecal spotting on orlistat.
OBJECTIVE
The intermittent loss of oil or stool ("spotting") is an adverse effect that occurs in patients taking orlistat; the pathophysiology is unknown. This study was designed to investigate the local effects of orlistat, free fatty acids, and the effects of the physical properties of rectal contents on anorectal function and continence.


METHODS
Anorectal physiology and continence function were assessed in ten healthy patients after the application of four test enemas: 1) high-viscosity stool substitute, 2) stool substitute with free fatty acid, 3) low-viscosity oil with placebo, 4) oil with orlistat. Rectal function and capacity were assessed by barostat techniques. Anal resting pressure, squeeze pressure, and squeeze duration were assessed by manometry. A retention test was performed using the same enemas as a quantitative assessment of continence.


RESULTS
Orlistat and free fatty acid had no adverse effects on anorectal function or continence. For each enema, the maximum volume retained correlated with rectal capacity (r = 0.85; P < 0.01). Continence during rectal filling was better maintained for high-viscosity stool substitute than low-viscosity oil enemas (P < 0.03). Patients able to maintain effective squeeze pressure retained more of the low-viscosity enemas than those with short squeeze duration (P < 0.01); in contrast, the volume retained of high-viscosity enemas was unaffected by anal sphincter function.


CONCLUSIONS
The physical properties of rectal contents, rectal capacity, and voluntary anal sphincter function have effects on continence function in healthy patients. The occurrence of spotting may depend on both intrinsic anorectal function and the effects of orlistat on the volume and physical properties of stool.
Fox
Mark
M
Department of Gastroenterology and Hepatology, University Hospital of Zürich, Zürich, Switzerland.
Schwizer
Werner
W
Menne
Dieter
D
Stutz
Bernadette
B
Fried
Michael
M
Thumshirn
Miriam
M
D000284:Administration, Oral; D000328:Adult; D001003:Anal Canal / Q000503:physiopathology; D000704:Analysis of Variance; D019440:Anti-Obesity Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000378:metabolism; D015984:Causality; D018592:Cross-Over Studies; D003672:Defecation; D004733:Enema; D005230:Fatty Acids, Nonesterified / Q000009:adverse effects / Q000032:analysis; D005242:Fecal Incontinence / Q000139:chemically induced* / Q000378:metabolism / Q000503:physiopathology; D005243:Feces / Q000737:chemistry; D005260:Female; D005766:Gastrointestinal Contents / Q000737:chemistry; D006801:Humans; D007408:Intestinal Absorption; D007783:Lactones / Q000008:administration & dosage / Q000009:adverse effects* / Q000378:metabolism; D016014:Linear Models; D008297:Male; D008365:Manometry; D008657:Metabolic Clearance Rate; D000077403:Orlistat; D010938:Plant Oils; D012007:Rectum / Q000503:physiopathology; D012677:Sensation; D014783:Viscosity
D019440:Anti-Obesity Agents; D005230:Fatty Acids, Nonesterified; D007783:Lactones; D010938:Plant Oils; D000077403:Orlistat