The Exploration of a Novel Biodegradable Drug-Eluting Biliary Stent: Preliminary Work

To explore the degradation, drug release, and mechanical properties of drug-incorporated films made of different ratios of poly(lactic-co-glycolic acid) (PLGA) and different amounts of paclitaxel (PTX), which may serve as the material platform for the manufacturing of biodegradable drug-eluting biliary stents.

PLGA of different lactic acid/glycolic acid ratios (50/50, 70/30, and 80/20) and 0%, 10, 20, and 30% weight by weight (w/w) PTX was mixed to make PLGA films, which were then cut into small pieces for further testing. Films were immersed in phosphate-buffered saline (pH 7.4) for a maximum of 11 weeks. Samples were taken randomly at Day 2, 4, 6, 8, 10, 12, 14, and weekly thereafter until Week 11 to test tensile strength, weight loss, pH value of the soaking solution, and drug release. The morphology of films was observed using scanning electron microscope (SEM).

At Week 10 of degradation, PLGA 80/20 still withstood a tensile strength of 9.7 newton (N), while PLGA 50/50 and 70/30 cracked spontaneously since Day 4. At Week 11, weight loss of PLGA 50/50, 70/30, and 80/20 was 95.15, 82.32, and 16.17%, respectively; and the lowest pH value of soaking solution was 1.87, 1.95, and 6.58, respectively. Drug release of 10, 20, and 30% PTX groups was 3.52-4.48%, 1.90-2.26%, and 1.44-2.06%, respectively. SEM proved smooth films before degradation; however, after the tensile strength was lost, cracks could be seen.

The degradation rate of PLGA can be controlled by altering lactic acid/glycolic acid ratio. Overall, PLGA 50/50 and 70/30 degrade significantly faster than 80/20. PLGA can serve as an effective drug carrier for PTX while being the stent strut, and PTX can be slowly released as PLGA degrades.