PSYCHOPHARMACOLOGY AND ABUSE POTENTIAL OF TRANSNASAL BUTORPHANOL

The effects of butorphanol administered by a nasal spray (transnasal, TN) and by intramuscular (IM) injection were compared to determine the onset of action, relative potency, profile of effects, and relative a buse liability of TN butorphanol. TN/IM placebo and TN and IM butorpha nol (1, 2, and 4 mg) were tested in seven male opioid abusers not curr ently physically dependent on opioids using a double-blind, double-dum my, Latin square design. Measures of subjective, behavioral and physio logical response were assessed. The onset and duration of action of bu torphanol administered by the IM and TN routes were similar at low dos es, but onset of TN butorphanol 4 mg was slower than that of 4 mg IM. IM butorphanol produced miosis, some opiate-like behavioral and subjec tive effects, and increasing dysphoric sedation and perceptual effects with increasing dose. TN and IM butorphanol 1 and 2 mg produced effec ts that were qualitatively and quantitatively similar; however, TN but orphanol 4 mg was less potent than 4 mg IM. Pharmacodynamic evidence s uggests that the abuse potential of TN butorphanol is not different fr om that of IM butorphanol.