Pro-Pheroid-based antiretroviral formulations : HPLC method development and stability studies

Abstract

HIV/AIDS poses an enormous healthcare challenge worldwide and it has become one of the leading causes of death in children. Globally, the number of people living with HIV has risen from around 8 million in 1990 to more than 33.2 million today (AVERT, 2008). According to UNAIDS (2008) and WHO (2008), 1.7 million adults and 330 000 children died from AIDS related disease in 2007. Due to the continual mutation of the HI virus, causing resistance to existing ARV's, it is essential to either develop new drugs or to design delivery systems that would increase the efficacy of existing ARV's. Pheroid™ technology is a novel delivery system consisting mainly of modified essential fatty acids. The effectiveness of Pheroid™ technology has been proven by several national and international clinical trials for formulations based on this technology (Grobler et al., 2008). The Pheroid™ is similar to an emulsion, but contains two liquid phases, as well as a dispersed gas phase, which are associated with the fatty acid dispersed phase. The one liquid phases is aqueous, the other is oil-based. Pro-Pheroid production is identical to that of the Pheroid™, except that no aqueous phase is introduced. Instead, drug substances are introduced to the oil phase. This study was conducted to determine the respective stabilities of three ARV's in the pro-Pheroid delivery system. High performance liquid chromatography (HPLC), was used to evaluate the stability of each ARV in the pro-Pheroid system. The analytical methods were developed and validated in-house. The three formulations were stored at 5°C, 25°C+60%RH, 30°C+65%RH and 40°C+75%RH for three months. Accelerated stability trials were performed according to ICH guidelines. It was found that nevirapine is stable in formulation with pro-Pheroid and that its assay results complied with the in-house specifications (lnitial% ± 5%). Due to the positive results obtained, the nevirapine formulation may be further developed to obtain a commercially viable product. The stability data for abacavir sulphate and efavirenz are inconclusive. Assay results of abacavir sulphate and efavirenz in the pro-Pheroid did not conform to in-house specifications. Further study is needed to ascertain the cause(s) of the variable results obtained. Before these ARVs can be formulated into possibly viable products, the following issues will have to be addressed: • The Pheroid™/pro-Pheroid manufacturing process will have to be assessed and validated to ensure lot uniformity. • Analytical methods for evaluating the pro-Pheroid system in particular, need to be developed and validated. Once such methods are available, the stability of the pro-Pheroid system should be evaluated over a minimum of 6-months period. Only once its stability has been confirmed, should active substances be added. • Separate analytical methods will have to be developed and validated for each formulation containing pro-Pheroid and the respective ARVs. • The physico-chemical properties of each ARV need to be taken into account in future formulation. • Parameters, such as viscosity and particle sizes, will have to be optimised to ensure stability of suspensions. This will most likely also increase the uniformity of samples taken for HPLC assay.