VAGINAL DELIVERY OF A HYDROPHOBIC ANTIRETROVIRAL DRUG CSIC FOR HIV PREVENTION: NOVEL FORMULATION STRATEGIES FOR IMPROVED DRUG SOLUBILIZATION AND LYMPHATIC TARGETING

[摘要] HIV epidemic is an ongoing health concern globally. Sexual transmission accounts for the overwhelming majority of new infections. Vaginal microbicides are under investigation as pre-exposure prophylaxis (PrEP) products for HIV prevention. Although progress has been made, the development of more efficacious products is warranted. Cervicovaginal tissue and draining lymph nodes contain an adequate amount of HIV target cells and play critical roles in HIV replication and sedimentation at the early stage of infection. Improved efficacy can be achieved with the use of specially designed drug delivery systems which achieve greater drug concentrations in these two sites of action. In this dissertation, we hypothesized that the hydrophobic microbicide candidate CSIC can be formulated in a polymeric vaginal film and a nanocrystal formulation with high loading capacities using multiple formulation strategies. We further hypothesized that the nano-delivery strategy can improve cervicovaginal tissue drug penetration and achieve lymphatic drug delivery. Series of preformulation studies were conducted to evaluate the physicochemical and biological properties of the drug candidate CSIC.The major challenge for CISC formulation development was identified as its hydrophobicity. Therefore, a cosolvent system comprising PEG 400, propylene glycol, and glycerin at a ratio of 5:2:1 has been optimized and utilized in a polymer based vaginal film formulation for increased drug solubility, long term stability, and lack of leakage. Additionally, a CSIC nanocrystal formulation, with a particle size of 243nm and near neutral surface charge, was developed. CSIC nanocrystals have been proved to possess increased drug saturation solubility, rapid mucus penetration properties, and improved drug permeation in the cervicovaginal tissue. More importantly, the pharmacokinetic study provided the first evidence of lymphatic targeting after intravaginal application without causing any epithelial damage. Furthermore, CSIC was able to release from the nanocrystals in a sustained mode, indicating its potential use as a coitally independent PrEP product that could improve user adherence. In summary, this work sets the stage to create new opportunities for sexually transmitted HIV prevention through the development of a novel dual targeting delivery system. The developed approaches can be used to deliver other drugs that lack solubility or require lymphatic targeting.

[发布机构] the University of Pittsburgh