In human studies of Butorphanol (see Clinical Trials), sedation is commonly noted at doses of 0.5 mg or more. Narcosis is produced by 10 to 12 mg doses of Butorphanol administered over 10 to 15 minutes intravenously.
Butorphanol, like other mixed agonist-antagonists with a high affinity for the k-receptor, may produce unpleasant psychotomimetic effects in some individuals.
Nausea and/or vomiting may be produced by doses of 1 mg or more administered by any route.
In human studies involving individuals without significant respiratory dysfunction, 2 mg of Butorphanol IV and 10 mg of morphine sulfate IV depressed respiration to a comparable degree. At higher doses, the magnitude of respiratory depression with Butorphanol is not appreciably increased; however, the duration of respiratory depression is longer. Respiratory depression noted after administration of Butorphanol to humans by any route is reversed by treatment with naloxone, a specific opioid antagonist (see OVERDOSAGE: Treatment section).
Butorphanol tartrate demonstrates antitussive effects in animals at doses less than those required for analgesia.
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The analgesic efficacy of Butorphanol tartrate injection in postoperative pain was investigated in several double-blind active-controlled studies involving 958 Butorphanol-treated patients. The following doses were found to have approximately equivalent analgesic effect: 2 mg Butorphanol, 10 mg morphine, 40 mg pentazocine, and 80 mg meperidine.