Effects of phenoxybenzamine on the narcotic withdrawal syndrome in the rat

The effects of various α- and β-adrenergic blocking agents on the narcotic withdrawal syndrome in rats were determined. α-Adrenergic blockers caused a dose-dependent suppression of two behavioural responses characteristic of precipitated narcotic withdrawal in the rat: diarrhoea and, most notably, wet-dog shakes. The β-adrenergic blocker, propranolol, did not effect the expression of the narcotic withdrawal syndrome. The effects of α-blockers on withdrawal behaviour did not appear to be due to the slight degree of sedation produced by the highest doses of the drugs, because pentobarbital and promethazine, in doses sufficient to induce marked sedation and anaesthesia, did not decrease the severity of withdrawal. In fact, pentobarbital appeared to exacerbate the abstinence syndrome.