Factors affecting the availability of organic nitrates from plastic infusion systems: structure of organic nitrate, nature of plastic and effect of temperature

Abstract

The organic nitrate most recently introduced for clinical use (isosorbide-5-mono-nitrate) is not lost by sorption into the plastics of infusion systems. Other organic nitrates with 2 or 3 nitrate groups are lost by sorption into the plastic matrix of infusion systems at ambient temperature. At higher temperatures, evaporation of nitroglycerin and ethylene glycol dinitrate from the plastic to the atmosphere also contributes to the total loss of these compounds. The temperature-dependent sorption of all 3 organic nitrates by the plastic infusion bags is accounted for by changes in the diffusion coefficients of the organic nitrates in the plastic matrix, the plastic-water partition coefficients being independent of temperature. The extent of loss of the 3 organic nitrates corresponds to the rank order of their plastic (and organic solvent)-water partition coefficients i.e. nitroglycerin > isosorbide dinitrate > ethylene glycol dinitrate. It is suggested that the chloroform-water partition coefficient may be a useful parameter for the prediction of the interaction of a drug with polyvinyl chloride infusion systems.