Epidural diamorphine and bupivacaine stability study

Abstract

Diamorphine and bupivacaine are commonly used together for spinal analgesia, although stability data relating to the mixture of the two drugs have not actually been established. We therefore performed a stability study using high performance liquid chromatography for both drugs and the British Pharmacopoeia 2,6-dimethylaniline limit test for bupivacaine, over a period of eight days and at room temperature. Diamorphine and bupivacaine were combined in various concentrations in 100 ml bags for use with the Bard patient controlled analgesia pump.

We found no significant change in concentration of either drug, and the 2,6- dimethylaniline limit test was well within set limits. We therefore conclude that it is safe to combine these two drugs in this way.