Adenosine in the inhibition of diazepam sedationby aminophylline

Abstract

Aminophylline in a low dose has been shown to reverse diazepam sedation. The present investigation was performed as a double-blind study to compare the effects of aminophylline and enprophylline on deep diazepam sedation after surgery. Enprophylline is a xanthine derivative with anti-asthmatic effect but, in contrast to aminophylline, enprophylline has very weak adenosine antagonistic properties. A comparison should make it possible to evaluate if adenosine is involved in the observed effects. Twenty male patients undergoing transurethral surgery in spinal anesthesia were given diazepam during surgery to maintain a state of deep sedation. Postoperatively aminophylline or enprophylline was given from coded ampoules in equipotent antiasthmatic doses (4.5 or 1.5 mg/kg). The degree of sedation was assessed prior to and after the injection. A difference between the groups was obvious. Patients given aminophylline showed rapid reversal of sedation, persisting throughout the 2-h observation period. Following enprophylline, a markedly slower reversal of sedation was observed. It is likely that aminophylline antagonizes diazepam sedation by blocking adenosine receptors. Some clinical implications are outlined.