Psychopharmacology
-
Randomized Controlled Trial Clinical Trial
Subjective, psychomotor, and analgesic effects of oral codeine and morphine in healthy volunteers.
The subjective, psychomotor, and physiological effects of analgesic doses of oral codeine and morphine were examined in 12 healthy volunteers. Subjects ingested placebo, morphine 20 or 40 mg, or codeine 60 or 120 mg in a randomized, double-blind, crossover design. The smaller and larger doses of each drug were putatively equianalgesic, and the cold-pressor test was included to test this assumption. ⋯ Plasma codeine and morphine levels varied as an orderly function of dose. These results suggest that oral codeine and morphine are appropriate drugs for outpatient pain relief because they are effective analgesics at doses that have only modest effects on mood, produce few side effects, and do not impair performance. The results also suggest a possible ceiling effect of codeine on analgesia and subjective effects.