D'Cruz Osmond J, Samuel Peter, Waurzyniak Barbara, Uckun Fatih M
Drug Discovery Program, Department of Reproductive Biology, Parker Hughes Institute, St. Paul, Minnesota 55113, USA.
Biol Reprod. 2003 Dec;69(6):1843-51. doi: 10.1095/biolreprod.103.019182. Epub 2003 Jul 30.
Stampidine [2',3'-didehydro-2',3'-dideoxythymidine 5'-[p-bromophenyl methoxyalaninyl phosphate], a prodrug of stavudine (STV/d4T) with improved anti-HIV activity, is undergoing development as a novel nonspermicidal microbicide. Here, we report the stability of stampidine as a function of pH, preparation of a novel thermoreversible ovule formulation for mucosal delivery, its dissolution profile in synthetic vaginal fluid, and its mucosal toxicity potential as well as systemic absorption in the rabbit model. Stampidine was most stable under acidic conditions. Stampidine was solubilized in a thermoreversible ovule formulation composed of polyethylene glycol 400, polyethylene glycol fatty acid esters, and polysorbate 80. Does were exposed intravaginally for 14 days to an ovule formulation with and without 0.5%, 1%, or 2% stampidine corresponding to 1 x 107- to 4 x 107-fold higher than its in vitro anti-HIV IC50 value. Vaginal tissues harvested on Day 15 were evaluated for mucosal toxicity and cellular inflammation. Additionally, does were exposed intravaginally to stampidine, and plasma collected at various time points was assayed by analytical HPLC for the prodrug and its bioactive metabolites. Stampidine did not cause mucosal inflammation. The vaginal irritation scores for 0.5-2% stampidine were within the acceptable range for clinical trials. The prodrug and its major metabolites were undetectable in the blood plasma. The marked stability of stampidine at acidic pH, its rapid spreadability, together with its lack of mucosal toxicity or systemic absorption of stampidine via a thermoreversible ovule may provide the foundation for its clinical development as an easy-to-use, safe, and effective broad-spectrum anti-HIV microbicide without contraceptive activity.
司他莫定[2',3'-二脱氢-2',3'-二脱氧胸苷5'-[对溴苯甲氧基丙氨酰磷酸酯]]是司他夫定（STV/d4T）的前药，具有增强的抗HIV活性，目前正在开发成为一种新型非杀精剂的杀菌剂。在此，我们报告了司他莫定在不同pH值下的稳定性、用于粘膜给药的新型热可逆胚珠制剂的制备、其在合成阴道液中的溶解曲线、其粘膜毒性潜力以及在兔模型中的全身吸收情况。司他莫定在酸性条件下最稳定。司他莫定可溶解于由聚乙二醇400、聚乙二醇脂肪酸酯和聚山梨酯80组成的热可逆胚珠制剂中。将雌兔阴道内给药14天，分别给予含0.5%、1%或2%司他莫定的胚珠制剂，其剂量比体外抗HIV IC50值高1×107至4×107倍。在第15天采集阴道组织，评估粘膜毒性和细胞炎症。此外，将雌兔阴道内给予司他莫定，在不同时间点采集血浆，用分析型高效液相色谱法检测前药及其生物活性代谢物。司他莫定未引起粘膜炎症。0.5%-2%司他莫定的阴道刺激评分在临床试验可接受范围内。在前药及其主要代谢物在血浆中未检测到。司他莫定在酸性pH下具有显著稳定性、快速扩散性，且通过热可逆胚珠给药时缺乏粘膜毒性或全身吸收，这可能为其作为一种易于使用、安全有效的无避孕活性的广谱抗HIV杀菌剂的临床开发奠定基础。
