In vitro drug release profiling of Sirolimus polymeric microparticles coated long-acting stents

In the realm of arterial disease interventions, drug-eluting stents (DES) have become a vital therapeutic choice in preventing atherosclerotic plaque formation and restenosis and facilitating vessel healing. Sirolimus-encapsulated poly Lactic-co-Glycolic acid (PLGA) Microparticles (MPs) were developed using solvent evaporation. MPs were freeze-dried with a cryoprotectant and coated on the stent surface using an efficient and reproducible nitrogen-assisted spray coating technique. The MPs displayed a uniform distribution particle size of 4.38 ± 1.1 μm, span value of 0.88 ± 0.02, coating mass transfer efficiency of 13.45 ± 1.1 % on the stent, and a coating time of ≤ 2 min per stent. Post sterilization, the particle size and morphology of the coated stents remained unchanged. Accelerated in vitro drug release profiles were evaluated under different conditions, indicating significant influences based on dissolution methods ranging from 28.2 %±4.3 %, 42.5 %±5.3 %, 76.6 %±4.7 %, and 84.25 %±3.1 % for dialysis bag (DB), vessel simulating flow-through cell (vFTC), flow-through cell (FTC), and sample and separate (SS) technique respectively for 48 h. The drug release mechanism from the coated stents is governed by the combination of the Korsmeyer Peppas and Higuchi models. The developed dissolution method exhibited discriminative effectiveness when evaluated with critical formulation attributes and process parameter variations. The 48 h accelerated drug release studies correlated well with the 6-month real-time release rate with an R² value of 0.9142 and Pearson's R2 of 0.9561. Ex-vivo studies demonstrated the permeation of MPs into artery tissues. Stability studies confirmed that MPs coated stents maintained desired properties at 4 °C and 30 °C/65 % RH for 6 months. Overall, these findings contribute to advancing stent technology, suggesting the potential for improvement of arterial interventions and enhanced patient outcomes.