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Effect of an enteric‐release formulation of naloxone on intestinal transit in volunteers taking codeine
Author(s) -
Hawkes N. D.,
Richardson C.,
Evans B. K.,
Rhodes J.,
Lewis S. J.,
Thomas G. A. O.
Publication year - 2001
Publication title -
alimentary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.308
H-Index - 177
eISSN - 1365-2036
pISSN - 0269-2813
DOI - 10.1046/j.1365-2036.2001.00970.x
Subject(s) - (+) naloxone , codeine , medicine , placebo , opioid , morphine , opioid antagonist , constipation , pharmacology , antagonist , analgesic , anesthesia , receptor , alternative medicine , pathology
Constipation is a common side‐effect of opioid therapy; in addition to their analgesic effect, opioids reduce intestinal secretion and motility with an increase in whole‐gut transit time. Naloxone, a specific opioid antagonist, reverses these effects but may also cause symptoms of opioid withdrawal in patients on long‐term therapy. Aim: To use an enteric‐release formulation, designed to produce a topical effect in the gut, with minimum systemic effects. Methods: Naloxone 10 mg b.d. and codeine 30 mg b.d. were used with identical placebo capsules in four sets of studies; 12 male volunteers were given the drugs alone and in combination, with a control study involving double placebo, during each of four study periods. Whole‐gut transit time was calculated and compared for each treatment period. Results: Naloxone, both alone and with codeine, significantly shortened the mean whole‐gut transit time compared with the control period, respectively, from 53.1 to 42.1 h ( P =0.005) and to 40.7 h ( P =0.024). Urgency to defecate was reported by two volunteers on naloxone alone and by three on combination therapy. Conclusions: The results show that the naloxone formulation counteracts the effect of codeine on intestinal transit, suggesting that it may have useful clinical applications.