Modification of antinociceptive action of morphine by Ukrain in rodents.

Morphine-induced (0.1 mg/kg s.c.)antinociceptive action was determined in rodents by using the writhing syndrome, hot plate and tail-flick tests. Ukrain given i.p. in doses equivalent to 0.05 and 0.1 LD50 did not affect the reactivity of the mice in the writhing syndrome test. Only in a dose of 0.1 LD50 did Ukrain produce an antinociceptive effect in the hot-plate and tail-flick tests. Ukrain significantly enhanced the antinociceptive effect of morphine in the hot-plate and tail-flick tests. The action of morphine was significantly suppressed by Ukrain in the writhing syndrome test in mice. These results indicated that Ukrain modified the antinociceptive action of morphine.