Evaluation of polycaprolactone matrices for sustained intravaginal delivery of a natural macromolecular microbicide, lactoferrin

Abstract

Polycaprolactone (PCL) matrices incorporating lactoferrin as a natural macromolecular microbicide, were prepared by rapidly cooling a suspension of lactoferrin particulates in PCL solution to induce crystallisation and hardening of the polymer. Thermal analysis revealed a 7% decrease in crystallinity of the PCL phase for 10% lactoferrin-loaded matrices compared with lactoferrin-free matrices and a 41% decrease in hardness of lactoferrin -loaded matrices, indicating a major influence of lactoferrin through inhibition of PCL crystal nucleation and growth. Exposure of the matrices to simulated vaginal fluid (SVF) at 37 °C resulted in rapid release of 13–14% of the lactoferrin content on day 1 and sustained delivery of the glycoprotein with high efficiency (90–95% of the content) over 14 days. SDS-PAGE analysis confirmed molecular weight preservation of the lactoferrin released from PCL matrices into SVF, indicating that it was not degraded during formulation and release. These findings recommend further investigations of PCL matrices as vaginal delivery systems for controlled release of macromolecular microbicides in the treatment and prevention of sexually transmitted infections.