Spinks Crystal B, Zidan Ahmed S, Khan Mansoor A, Habib Muhammad J, Faustino Patrick J
Department of Pharmaceutical Sciences, School of Pharmacy, Howard University, Washington, DC.
Division of Product Quality Research, Office of Pharmaceutical Quality, Food and Drug Administration, Silver Spring, MD, USA; Faculty of Pharmacy, Zagazig University, Zagazig, Egypt.
Clin Pharmacol. 2017 Feb 23;9:29-38. doi: 10.2147/CPAA.S119875. eCollection 2017.
Tenofovir, currently marketed as the prodrug tenofovir disoproxil fumarate, is used clinically to treat patients with HIV/AIDS. The oral bioavailability of tenofovir is relatively low, limiting its clinical effectiveness. Encapsulation of tenofovir within modified long-circulating liposomes would deliver this hydrophilic anti-HIV drug to the reticuloendothelial system for better therapeutic efficacy. The objectives of the current study were to prepare and pharmaceutically characterize model liposomal tenofovir formulations in an attempt to improve their bioavailability. The entrapment process was performed using film hydration method, and the formulations were characterized in terms of encapsulation efficiency and Caco-2 permeability. An efficient reverse-phase high-performance liquid chromatography method was developed and validated for tenofovir quantitation in both in vitro liposomal formulations and Caco-2 permeability samples. Separation was achieved isocratically on a Waters Symmetry C8 column using 10 mM NaPO/acetonitrile pH 7.4 (95:5 v/v). The flow rate was 1 mL/min with a 12 min elution time. Injection volume was 10 µL with ultraviolet detection at 270 nm. The method was validated according to United States Pharmacopeial Convention category I requirements. The obtained result showed that tenofovir encapsulation within the prepared liposomes was dependent on the employed amount of the positive charge-imparting agent. The obtained results indicated that calibration curves were linear with > 0.9995 over the analytical range of 1-10 µg/mL. Inter- and intraday accuracy and precision values ranged from 95% to 101% and 0.3% to 2.6%, respectively. The method was determined to be specific and robust. Regarding the potential of the prepared vectors to potentiate tenofovir permeability through the Caco-2 model, a 10-fold increase in tenofovir apparent permeability was observed compared to its oral solution. In conclusion, this novel and validated method was successfully applied to characterize both in vitro encapsulation efficiency and Caco-2 permeability transport for the pharmaceutical assessment of novel tenofovir formulations.
替诺福韦目前作为前药富马酸替诺福韦二吡呋酯上市，临床上用于治疗艾滋病毒/艾滋病患者。替诺福韦的口服生物利用度相对较低，限制了其临床疗效。将替诺福韦包裹在修饰的长循环脂质体内可将这种亲水性抗艾滋病毒药物递送至网状内皮系统，以提高治疗效果。本研究的目的是制备模型脂质体替诺福韦制剂并对其进行药学表征，以提高其生物利用度。包封过程采用薄膜水化法进行，制剂通过包封效率和Caco-2渗透性进行表征。开发并验证了一种高效反相高效液相色谱法，用于测定体外脂质体制剂和Caco-2渗透性样品中的替诺福韦含量。在Waters Symmetry C8柱上采用10 mM NaPO/乙腈pH 7.4（95:5 v/v）等度洗脱实现分离。流速为1 mL/min，洗脱时间为12 min。进样量为10 µL，在270 nm处进行紫外检测。该方法根据美国药典委员会I类要求进行验证。所得结果表明，制备的脂质体内替诺福韦的包封率取决于所使用的赋予正电荷的试剂的量。所得结果表明，校准曲线在1-10 µg/mL的分析范围内呈线性，r > 0.9995。日内和日间准确度和精密度值分别在95%至101%和0.3%至2.6%之间。该方法具有特异性和稳健性。关于制备的载体增强替诺福韦通过Caco-2模型的渗透性的潜力，与口服溶液相比，替诺福韦的表观渗透率提高了10倍。总之，这种新颖且经过验证的方法成功应用于表征新型替诺福韦制剂的体外包封效率和Caco-2渗透性转运，以进行药学评估。
