Lidocaine stability in cardioplegic solution stored in glass bottles and polyvinyl chloride bags

The stability of lidocaine hydrochloride in buffered cardioplegic solutions stored in glass and polyvinyl chloride bags was studied. Concentrations of lidocaine (incorporated as the hydrochloride salt) were measured in buffered cardioplegic solutions containing potassium chloride, sodium bicarbonate, dextrose, and sodium chloride. Solutions were stored at 22 +/- 2 degrees C and 4 degrees C in glass bottles and 500-ml and 250-ml polyvinyl chloride (PVC) containers; some 250-ml PVC bags were underfilled to study the effects of varying surface area-volume ratios. Lidocaine concentrations were measured using a homogeneous enzyme immunoassay (EMIT, Syva Corporation) on days 0, 1, 2, 7, and 21. Lidocaine concentrations decreased significantly in all PVC bags stored at 22 degrees C and in underfilled PVC bags stored at 4 degrees C. Lidocaine loss in PVC bags appeared to result from sorption. It is concluded that lidocaine is stable in cardioplegic solutions when these are refrigerated and stored in glass containers or filled large-volume PVC bags for 21 days.