Evaluation of tacrolimus sorption to PVC- and non-PVC-based tubes in administration sets: Pump method vs. drip method

Tacrolimus sorption to tubes was evaluated using pump and drip methods For tubes, polyvinylchloride (PVC)- and non-PVC-based (polyurethane [PU] and polyolefin [PO]) tubes were used. First, inner surface properties of tubes were analyzed using field emission scanning electron microscopy and X-ray photoelectron spectroscopy. Tacrolimus was quantitatively analyzed using high-performance liquid chromatography with UV detection. For kinetic sorption analysis, diluted tacrolimus to 10 μg/mL was passed through 1-m-long tubes at 10 mL/h. Samples were collected at 1–4 h. The inner surface of PO-based tubes was relatively smooth and soft compared with those of PVC- and PU-based tubes. Atomic compositions of tubes matched chemical formulas of polymers excluding low-level impurity in PVC-based tubes. Tacrolimus was successfully analyzed and linearly determined at 2.5–20 μg/mL. From both methods, PVC- and PO-based tubes exhibited the highest and the lowest (<10%) sorption levels to tacrolimus, respectively. Tacrolimus was stably delivered using the pump method. Results suggested that the pump method can estimate tacrolimus sorption in administration set tubes and evaluate other sorptional drugs used at low concentrations. PO-based tubes also have promising potential as an alternative for administration set tubes.