The release kinetics of drug eluting stents containing sirolimus as coated drug: role of release media.

Prior understanding on the in vitro release profile of the drug from drug eluting devices such as stent (DES) is crucial in designing and optimizing the drug embedded coating or matrices. In fact, assessing in vitro release profile is a mandatory requirement prior to the clinical evaluation of DES. The in vitro release is also employed to estimate parameters such as T1/2. The release profile largely depends on the release medium selected for the studies. Normally PBS with a pH of 7.4 is used for assessing the release kinetics of the drug. Often drug undergoes irreversible changes such as hydrolysis in PBS leading to erroneous assessment of the release profile. This is particularly true in the case of sirolimus, one of the widely used drugs in various applications. We studied the influence of various media on the release profile of sirolimus from DES. The data generated suggested that a release medium consisting of 9:1 (v/v) of normal saline and isopropanol is a most suitable one for assessing in vitro the release kinetics of sirolimus from DES.