Opioid and opioid-like drug effects on whole-gut transit measured by scintigraphy.

Unlabelled: We studied the effects of several drugs on gastrointestinal transit (tramadol HCl, acetaminophen with codeine and placebo) in a randomized, double-blind, crossover study.

Methods: Combined gastric emptying, small bowel and colonic transit scintigraphy was performed in 12 normal subjects. Each subject received a standardized diet and study drug on Days 1-5. On Day three, subjects received a radiolabeled solid and liquid phase meal.

Results: No significant difference in the gastric T1/2 (mean +/- s.e.m.) of solids for placebo (69 +/- 7 min), APAP/C (74 +/- 15 min) or tramadol (686 +/- 8 min) (p = 0.86) were seen. Similarly there was no significant difference in the T1/2 of liquids for placebo (31 +/- 4 min), APAP/C (41 +/- 6 min) (p = 0.29). Orocecal transit times were not significantly different for placebo (237 +/- 20 min), APAP/C (311 +/- 26 min) or tramadol (311 +/- 10 min) (p = 0.12). Colon geometric centers (GC) for placebo at 24, 48 and 72 hr were 4.6 +/- 0.35, 6.0 +/- 0.28 and 6.8 +/- 0.08. The GC for tramadol and APAP/C were all significantly lower at 72 hr, 6.4 +/- 0.17 and 6.2 +/- 0.17, respectively compared to the placebo. The GC of tramadol at 24 and 48 hr (3.8 +/- 0.4, 5.4 +/- 0.26) were not significantly different from placebo. In contrast, the GC for APAP/C at 24 and 48 hr (3.3 +/- 0.31, 5.0 +/- 0.26) were significantly delayed. All subjects recorded a significant increase in constipation on drugs compared to placebo (p = 0.04).

Conclusion: Tramadol and APAP/C had no effect on gastric emptying or small bowel transit. At equianalgesic doses, tramadol caused less delay in colonic transit than APAP/C for 48 hr and delay in the GC agreed with the subjective complaints of constipation on both drugs.