STABILITY OF ADMIXTURES OF PETHIDINE AND METOCLOPRAMIDE IN AQUEOUS-SOLUTION, 5-PERCENT DEXTROSE AND 0.9-PERCENT SODIUM-CHLORIDE

Objective: To study the stability of admixtures of pethidine and metoc lopramide in aqueous solution, 0.9% sodium chloride and 5% dextrose pr eparations. Method: Aqueous mixtures of 1 mi of 50 mg/ml pethidine wit h 2 ml of 5 mg/ml metoclopramide were prepared in plastic syringes, wh ile the 0 9% sodium chloride and 5% dextrose admixtures, each containi ng 7.35 mg/ml of pethidine and 0.15 mg/ml of metoclopramide, were prep ared in infusion bags. The preparations were stored under light and da rk conditions at 32 degrees C for 48 h. Samples were collected at 0, 0 5, 1, 2, 4, 6, 8, 24, 32 and 48 h. A high-performance liquid chromato graphic method was developed to separate and quantify both drugs. Resu lts: All preparations were found to be physically and chemically stabl e for at least 48 h, as concentration changes were within 10% of their initial level, with no development of haze, precipitate or colour. Li ght appeared to have a negligible effect. Although pH changes were obs erved, they were inconsistent and were within the ranges in which the drugs are expected to remain stable. Pethidine and metoclopramide admi xtures can, therefore, on stability grounds be used for the concomitan t management of pain, nausea and vomiting.