Compatibility with medical plastics and stability of continuously and simultaneously infused isosorbide dinitrate and heparin

Abstract The compatibility and stability of continuously infused isosorbide dinitrate (ISDN) and heparin with medical plastics were investigated by simulating therapeutic conditions practiced in hospital. High-performance liquid chromatography (HPLC) with UV detection and C18 column was used to quantify the drugs. The results show that the compatibility of ISDN and heparin solutions with polypropylene syringesduring a 12 h continuous infusion is good. Preparing the syringes 8 h in advance does not alter the stability of the drugs, as long as the ISDN is not refrigerated (at + 4°C). The stability of ISDN with PVC/PE tubing (polyvinyl chloride on the outside and polyethylene inside) is also satisfactory irrespective of whether it is administered alone or mixed with heparin. The behaviour of heparin with the PVC/PE tubing is more difficult to interpret, since the variations in concentration near 10% of the initial concentration of heparin. ISDN and heparin both have a compatibility problem with PVC tubing. ISDN is rapidly fixed on PVC and then released: it is released earlier when it is administered with heparin in the tube. Some heparin is lost in the PVC tubing. This loss is relatively stable with time and is similar and independent of the type of infusion solvent, or whether heparin is used by itself or in combination with ISDN.