Dissolution of DEHP from PVC Administration Tube. Estimation of DEHP Dissolution Based on HCO 60 Concentration and Drip Conditions.

Di-2-ethylhexyl Phthalate (DEHP) is reported to have been formed and identified in a polyvinyl chloride (PVC) administration tube during the infusion of an injection fluid containing polyoxyethlated caster oil (HCO60) as a solvilizing agent.This paper describes a experimental formula for estimating the amount of DEHP dissolution, which was obtained under several drip conditions and using an aqueous solution of HCO60.The DEHP concentration was determined using HPLC. The DEHP dissolution followed a general pattern, in which the DEHP concentration in the solution linearly increased over time as first and thereafter reached a plateau. The amount of DEHP dissolution depended on the drip conditions. The maximum (plateau) DEHP concentration CD (μg/mL) was proportional to the square root of the HCO60 concentration CH (mg/mL), the length of the tube H (cm) and the inner diameter of the tube R (cm), but was inversely proportional to the drip rate S (mL/hr). The time T1 (hr), which becomes CD=aT1 (a : inclination of the graph before reaching it in plateau), was proportional to H and R2, but inversely proportional to S.T1 was not dependent on CH. Based on these results, the formula for calculating the total amount of dissolution of DEHP Dtotal (μg) during the total time of the infusion T (hr) was determined to be as follows : Dtotal=4.09RH√CH (T-0.755R2H/S).The application of this formula will make it easier to estimate the amount of DEHP intake by patients during the infusion of an injection containing HCO60 using a PVC administration tube.