Dependence liability of two antidiarrheals, nufenoxole and loperamide

We compared the dependence liabilities of therapeutic doses of nufenoxole and loperamide. Ten subjects received 10 mg nufenoxole every 12 hr for 10 days, and 9 others received 4 mg loperamide every 12 hr for 10 days. On the eighth day of drug a sensitive single-blind intravenous naloxone challenge was used to assess dependence liability. After 0.2, 0.4, and 0.6 mg naloxone, pupillary constriction (0.618 to 0.540 cm, p less than 0.005) was measured in subjects receiving nufenoxole, whereas slight dilation (0.596 to 0.622 cm, p less than 0.05) was observed in those receiving loperamide. Trapezius electromyogram activity decreased by 30% for nufenoxole and 12% for loperamide. There were slight decreases in core and skin temperatures (0.06 degrees to 0.12 degrees) in both groups, partly attributable to experimental conditions. Changes in physiologic measurements after naloxone were similar in both groups and not of sufficient importance to suggest physical dependence liability for either loperamide or nufenoxole at the doses used.