The analgesic tramadol has minimal effect on gastrointestinal motor function

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Abstract
The analgesic tramadol, an opioid agonist and monoaminergic reuptake blocker, has been assumed to interfere less with gastrointestinal motor function than other opioid analgesics, but this has not been specifically investigated. In this study we examined the effect of tramadol on variables of gastrointestinal motor function. Ten healthy volunteers participated in a two-arm, placebo-controlled, double-blind, randomized, cross-over study comparing tramadol 50 mg and placebo solutions given four times a day for 10 days. Oro-caecal (lactulose H2-breath test) and colonic (solid markers) transit times and anal sphincter pressures were measured after 10 days dosing. Median oro-caecal transit time was 90 min (interquartile range: 75-105) with placebo and 90 min (60-105) with tramadol (not significant). The median total colonic transit time increased from 45.6 h (25.2-64.8) with placebo to 58.8 h (50.4-78.0) with tramadol (not significant), which is still within the normal range (< 60 h). Anal sphincter resting pressures were not significantly changed by tramadol compared with placebo. Tramadol has a minor delaying effect on colonic transit, but no effect on upper gastrointestinal transit or gut smooth muscle tone. Tramadol may be a useful analgesic where interference with gut motor function is undesirable.