FENTANYL-INDUCED MUSCLE RIGIDITY AS AFFECTED BY PRETREATMENT WITH AMANTADINE HYDROCHLORIDE

Study Objective: To determine whether the degree of muscle rigidity in humans caused by the administration of high-dose fentanyl is affected by pretreatment with amantadine hydrochloride, a drug that stimulates the release of dopamine in the basal ganglia. Design: Randomized, observer-blinded comparison of regimes. Setting: Inpatient surgery at a university-affiliated teaching hospital. Patients: Sixteen patients scheduled for elective surgery in whom the administration of high-dose fentanyl was felt to be appropriate. Interventions: Eight patients in the control group were given diazepam 5 mg orally 1 hour prior to induction of anesthesia. Eight patients in an experimental group were given the same dose of diazepam and also were treated with amantadine 1 g orally in divided doses over a period of 25 hours prior to their scheduled surgery. At the time of surgery, all patients were given fentanyl 50 mug/kg intravenously at a rate of 1 mg/min and were clinically evaluated for the degree of muscle rigidity of the chest wall, abdomen, and extremities. Measurements and Main Results: A single observer, blinded to the technique, evaluated and recorded the degree of muscle rigidity present in the chest wall, abdomen, and upper extremities immediately after administration of the fentanyl and 3 minutes later. The observer was the same individual in all instances. In no case did the muscle rigidity compromise our ability to adequately oxygenate the patient. Conclusions: Muscle rigidity associated with the administration of high-dose fentanyl is not attenuated by prior administration of amantadine in the dose range studied.