EXCRETION OF COMBINED MORPHINE IN THE TOLERANT AND NON-TOLERANT DOG

¹ From the Department of Pharmacology, State University of Iowa, Iowa City

1. The "combined morphine" in urine of morphinized dogs may be separated into "easily" and "difficultly hydrolyzable" fractions.

2. Tolerant dogs excrete relatively greater amounts of the "easily hydrolyzable" fraction of the combined morphine than do non-tolerant dogs.

3. Seven to twenty-four hours after injection of morphine, urine of tolerant dogs contains mostly free morphine. During this same period, non-tolerant dogs excrete relatively large amounts of the "difficultly hydrolyzable" morphine fraction.

4. Tolerant dogs reach a peak in rate of morphine excretion more quickly than do the non-tolerant animals. The latter, however, continue to excrete relatively large quantities of morphine after the drug has practically disappeared from the urine of tolerant dogs.