ATCvet code: QNO2AF01
Pharmacotherapeutic group: Analgesics, Opioids, Morphinan derivatives
Pharmacodynamics
The veterinary medicinal product contains butorphanol, a centrally acting analgesic showing opioid -agonist and -antagonist activity. Its analgesic activity is about 4-7 times that of morphine, and its narcotic antagonist activity about 1/40 that of naloxone. Analgesic effects are dose-related, and in the horse last 15-90 minutes. Butorphanol assists in the production of profound sedation in combination with detomidine, medetomidine, or romifidine; in the production of sedation and analgesia in combination with acepromazine as a premedicant to general anaesthesia; pre-operative analgesia prior to induction of anaesthesia with a variety of agents. In high doses, respiratory depression followed by cardiovascular depression can occur.
Pharmacokinetics
After intravenous injection in horses of butorphanol at 0.1 mg/kg, the elimination half-life is brief with a Cmax of 680.6±568.5 ng/ml at 5 minutes post-treatment. A mean plasmatic butorphanol concentration of about 5 ng/ml three hours post injection is observed. It is metabolized in the liver and eliminated by the urine.
Preclinical studies and clinical experience have shown that analgesic effects are seen within 15 minutes of injection and last approximately 2 hours.