Determination of the in Vitro Degradation Products of Poly(Lactide-Co-Glycolide) Stent Coating by High Performance Liquid Chromatography

In order to investigate the in vitro degradation of polymer coating in a new absorbable zinc alloy drug-eluting coronary stent system (stent), the work as mentioned by the title was done. The stent was suspended in a 50 mL centrifuge tube, and 10 mL of phosphate buffer solution preheated to 37℃ was added to immerse the stent, which was shaking at 37℃. On 0, 7, 14, 21, 28 d, the degradation solution was collected, adjusted to pH 2.8±0.2 with phosphoric acid, filtered through 0.20 μm membrane, and determined by high performance liquid chromatography. The morphology was observed to evaluate the degradation of the drug coating. As shown by the results, linear relationships between values of peak area and mass concentration of glycolic acid and L-lacticacid were found in definite ranges, with detection limits (3S/N) of 0.50 mg·L^-1 and 0.70 mg·L^-1, respectively. Test for precision was carried out on blank spiked water samples, with RSDs (n=6) in the range of 0.12%-2.7%. Test for recovery was made on the blank samples by standard addition method, giving results in the range of 91.6%-118%. According to the cumulative amounts of degradation products, the polymer coating in the stent was basically completely degraded in 28 d.