Stability of fentanyl, bupivacaine and adrenaline solutions for extradural infusion

Abstract

Fentanyl and bupivacaine were tested for their stability when diluted with 0.9% sodium chloride to 4 μg ml-1 and 0.1%, respectively, in 100-ml polyvinyl chloride (PVC) bags, alone and in combination, with and without adrenaline 1:200 000. Changes in drug concentration and pH were investigated for 56 days. The combination of fentanyl, bupivacaine and adrenaline was tested under varying environmental conditions of 35 °C, 4 °C, - 18 °C, room temperature, darkness and after autoclaving. Fentanyl and bupivacaine were adsorbed onto PVC, resulting in reductions of 12.6% and 9.6% drug mass, respectively, at day 3, but remained stable thereafter. Adrenaline was progressively degraded to a maximum reduction of 37.3% at 35 °C by day 56. Solutions containing adrenaline became more acidic over 56 days. Fentanyl and bupivacaine were stable. © 1992 British Journal Anaesthesia.