Sedative efficacy of droperidol and diazepam in the rat

Droperidol and diazepam were evaluated for sedative properties in 12 male Sprague Dawley rats (Rattus norvegicus). Over a period of several weeks, each rat was treated subcutaneously with 0.5 mg droperidol/kg, 2.0 mg droperidol/kg, 5.0 mg diazepam/kg, 15.0 mg diazepam/kg, and physiologic saline according to a randomized schedule. After each treatment, the animals were evaluated for their response to a series of four common clinical manipulations (tail-vein bleeding, orbital bleeding, teeth clipping, and toenail bleeding) at five time points over the 90 min following the injection. Rats were scored on the basis of their responses to each manipulation. Response to cardiac puncture was assessed once in each animal immediately prior to euthanasia. Histologic lesions associated with subcutaneous and intramuscular administration of these drugs were evaluated in a separate group of animals. Results indicate that both droperidol and diazepam (at either dose) allow easier manipulation for toenail bleeding and teeth clipping when compared with saline control. There was no advantage in using these sedatives for tail-vein bleeding. Orbital bleeding could not be performed humanely with either drug. Diazepam at a dose of 15.0 mg/kg allowed humane cardiac puncture. Subcutaneous injection of diazepam or 2.0 mg droperidol/kg resulted in various degrees of inflammation revealed by histologic examination, although no clinical signs were associated with these lesions. Subcutaneous administration of droperidol at a dose of 0.5 mg/kg is recommended for nonpainful, noninvasive manipulations as it provides adequate sedation for most procedures without inducing the subcutaneous inflammation observed with diazepam or 2.0 mg droperidol/kg.(ABSTRACT TRUNCATED AT 250 WORDS)