Stability of thyroid hormones during continuous infusion.

We investigated the stability of thyroid hormones during a mode of continuous drug infusion via polypropylene tubing using the same conditions that would be applied to treating patients in a hospital setting. The diluted thyroid hormones were prepared using aseptic technique, stored at 2-8°C (36-46°F) and tested within 24 h of preparation for stability and percent recovery from within plastic tubing. Experiments were done in duplicate with triplicate sets of readings for each assay point. Only T(4) prepared with 5% dextrose water (D5W) containing 1 mg/mL albumin remained constant, stable, predictable and accurate over time under various conditions. Other methods of preparation lost drug by adhering to the plastic containers and tubing by as much as 40% of starting concentration. T(3) recovery in the presence of 1 mg/mL of albumin was 107±2% (mean±standard error of the mean) of anticipated drug concentrations. We conclude from this series of experiments that to maintain an accurate and stable dosing of patients receiving intravenous thyroid hormones, 1 mg/mL of albumin must be added to the infusate to prevent lost on the plastic intravenous tubing.