Abstract
Polymeric implants loaded with drugs can overcome the disadvantages of oral or injection drug administration and deliver the drug locally. Several methods can load drugs into polymers. Herein, soaking and supercritical CO2 (scCO2) impregnation methods were employed to load aspirin into poly(l-lactic acid) (PLLA) and linear low-density polyethylene (LLDPE). Higher drug loadings (DL) were achieved with scCO2 impregnation compared to soaking and in a shorter time (3.4 ± 0.8 vs. 1.3 ± 0.4% for PLLA; and 0.4 ± 0.5 vs. 0.6 ± 0.5% for LLDPE), due to the higher swelling capacity of CO2. The higher affinity of aspirin explained the higher DL in PLLA than in LLDPE. Residual solvent was detected in LLDPE prepared by soaking, but within the FDA concentration limits. The solvents used in both methods acted as plasticizers and increased PLLA crystallinity. PLLA impregnated with aspirin exhibited faster hydrolysis in vitro due to the catalytic effect of aspirin. Finally, PLLA impregnated by soaking showed a burst release because of aspirin crystals on the PLLA surface, and released 100% of aspirin within 60 days, whereas the PLLA prepared with scCO2 released 60% after 74 days by diffusion and PLLA erosion. Hence, the scCO2 impregnation method is adequate for higher aspirin loadings and prolonged drug release.
Highlights
Acetylsalicylic acid is a common anti-inflammatory drug and is widely prescribed as an anti-platelet to prevent cardiovascular events [1,2,3]
We reported that the mass of CO2 sorbed in linear low-density polyethylene (LLDPE) is less than half that sorbed in poly(L-lactic acid) (PLLA) in the same conditions
This paper investigated aspirin loading in PLLA and LLDPE through soaking and supercritical CO2 impregnation methods to develop local delivery systems as an alternative to oral administration
Summary
Acetylsalicylic acid (aspirin) is a common anti-inflammatory drug and is widely prescribed as an anti-platelet to prevent cardiovascular events [1,2,3]. An alternative to oral administration is developing aspirin local delivery systems by loading the aspirin into polymeric implants for cardiovascular applications, such as stents [7,8,9,10], scaffolds [11,12,13], and gels [6]. Soaking is a conventional method that consists of immersing the polymer in a drugconcentrated solution, allowing the drug to diffuse into its amorphous regions and be retained due to interactions with the polymeric chains [14,16,17]. Soaking is a simple method and can be used to load a variety of drugs according to the right combination of {solvent + polymer + drug}
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