Fentanyl-induced muscle rigidity as affected by pretreatment with amantadine hydrochloride

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.

Randomized, observer-blinded comparison of regimes.

Inpatient surgery at a university-affiliated teaching hospital.

Sixteen patients scheduled for elective surgery in whom the administration of high-dose fentanyl was felt to be appropriate.

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 micrograms/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.

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.

Muscle rigidity associated with the administration of high-dose fentanyl is not attenuated by prior administration of amantadine in the dose range studied.