Properties of nylon 12 balloons after thermal and liquid carbon dioxide treatments.

Critical design attributes of angioplasty balloons include the following: tear resistance, high burst pressures, controlled compliance, and high fatigue. Balloons must have tear resistance and high burst pressures because a calcified stenosis can be hard and nominal pressures of up to 16 atm can be used to expand the balloon. The inflated balloon diameter must be a function of the inflation pressure, thus compliance is predictable and controlled.

A nonelutable low-molecular weight heparin stent coating for improved thromboresistance.

Low-molecular weight heparin (LMWH) has been widely used as a systemic anticoagulant during percutaneous coronary intervention. In this study, LMWH was covalently immobilized to the surface of a cobalt chromium reservoir-based sirolimus-eluting stent to create a nonelutable nanoscale coating for enhanced thromboresistance. Toludine-blue stained stents revealed uniform heparin coverage on all surfaces of the stent.

Control of cilostazol release kinetics and direction from a stent using a reservoir-based design.

Sustained release formulations of a potent antithrombotic drug, cilostazol, in poly-(lactic acid-co-glycolic acid) (PLGA) matrices were created for luminal release from a novel drug-eluting stent utilizing reservoirs (RES TECHNOLOGY™). The crystallinity of cilostazol and the morphology of the cilostazol/polymer matrix in the stent reservoirs were examined by cross-polarized optical microscopy and differential scanning calorimetry. An in vitro method was developed to study release kinetics of various cilostazol formulations and to examine correlation with in vivo release.

Morphological and degradation studies of sirolimus-containing poly(lactide-co-glycolide) discs.

The effect of residual solvent and copolymer ratio on the in vitro degradation and drug release behavior of a bioabsorbable polymer/drug system was investigated in an effort to understand and develop the use of these excipients for controlled drug delivery devices. Sirolimus-containing poly(lactide-co-glycolide) (PLGA) discs were fabricated by a solution-casting method using dimethyl sulfoxide (DMSO) as the solvent. The residual DMSO was removed from a set of discs by supercritical carbon dioxide extraction, and reflections of crystalline sirolimus were observed in the wide-angle X-ray scattering profile observed after extraction.

Microstructure and drug-release studies of sirolimus-containing poly(lactide-co-glycolide) films.

Sirolimus-containing poly(lactide-co-glycolide) (PLGA) films were prepared by solution casting and removing the residual solvent, 1,4-dioxane, by liquid and supercritical carbon dioxide (CO(2) ) extraction. The effect of lactide:glycolide ratio, stereochemistry of PLGA, and extraction condition (i.e.

Polymers for drug eluting stents.

Currently approved drug eluting stents (DES) consist of a metallic scaffold and an elutable drug dispersed in a polymer matrix that conformally surrounds the struts. These primarily biostable polymers bind the drug to the stent and modulate the elution of the drug into the arterial tissue. This chapter summarizes the key requirements for polymers used in the DES, including physical properties, stability, compatibility with drugs, biocompatibility with vascular tissue and control of drug release.