Compatibility studies on some commercially available gentamicin sulphate injections with commonly co-administered parenterals.

Compatibility of four brands of gentamicin sulphate injection with five parenteral drugs-dexamethasone, diazepam, hyoscine butylbromide, furosemide and promethazine were studied. These drugs are commonly used together in pre-anaesthetic or post-anaesthetic medications among others. For the different test situations, solutions of varying concentrations of gentamicin sulphate were prepared and mixed with the test drugs. After the test period, all the admixtures were evaluated for gentamicin potency, Ph changes, clarity and extent of interaction. Potency changes were determined by microbial assays while the extend of interaction was determined by chromatographic techniques. No significant changes in pH were observed in all the admixture studied. A significant reduction in potency was observed in all the admixtures of Gentarad. No significant interactions were observed based on the chromatographic studies.