Interaction between Ukrain and Naltrexone in the writhing syndrome test in mice

The interaction between Ukrain and Naltrexone, a nonselective opioid receptor antagonist, was studied in the 'writhing syndrome' test in mice. Naltrexone (1 mg/kg s.c.) was administered i.p. 30 min before Ukrain (2.375, 4.75, 9.5 and 19 mg/kg). In addition, the antinociceptive properties of Ukrain and Naltrexone in 10-day treatment in mice were studied. The results show that the antinociceptive effect of both single dose and prolonged administration of Ukrain is completely antagonized by Naltrexone.