A study of the interaction of selected drugs and plastic syringes

It is common hospital pharmacy practice to preload syringes with selected drugs and store them ready for use. Because the several components of syringes, (such as barrels, gasket seals, etc.) may vary among manufacturers, there exists the possibility that syringe components of differing provenance might interact e.g., by sorption, with stored drugs to differing degrees. To examine possible interactions, three brands of commercially available syringes were compared to determine what influence, if any, short term storage of injectable solutions might exert on the solutions or the syringes. Four drugs; dexamethasone sodium phosphate, diazepam, diatrizoate meglumine and nitroglycerin USP were individually loaded into 3 mL syringes and stored at temperatures between -20 degrees C and + 25 degrees C for periods from 6 hours to 30 days. The syringes were examined for any gross changes. Drug solutions were analyzed after storage to determine the presence of organic leachates from the syringes and any change from original drug concentration values. No syringes showed gross physical changes after storage with drug solution nor were any drug solutions found to contain leachates on gas chromatographic-mass spectroscopic analysis. Drug concentrations were seen to change following storage, the greatest changes occurring with the highly lipophilic drugs dexamethasone and diazepam. In most instances loss of drug concentration was most rapid at room temperature. Although there were clear differences among the three brands of syringe, no overall pattern emerged which might allow the selection or rejection of one syringe over another for the extemporaneous preloading of the drugs examined.