Formulation, in vitro release and transdermal diffusion of acyclovir and ketoconazole for skin conditions in HIV/AIDS patients
Jacobs, Gerda Alida
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The aim of this in vitro study was to investigate the efficacy of the novel Pheroid™ technology system in a semi-solid dosage form, for the topical delivery of acyclovir (5% w/w), an anti-viral agent and ketoconazole (2% w/w) an anti-fungal agent. The human immununodeficiency virus (HIV) had an immense impact on the spectrum of diagnosis of cutaneous diseases since its first manifestation in the late 1970's (Yen-More et al., 2000:432). The skin is the most commonly affected organ in HIV infected individuals with skin manifestations present in up to 92% of HIV-positive patients. According to Ramdial (2000:113) the skin may also be the first or the only organ affected throughout the course of the HIV/AIDS disease. HIV/AIDS patients are more susceptible to infections due to their compromised immune systems (Durden & Elewski, 1997:200) and an exceptionally wide range of infectious skin manifestations presents in HIV/AIDS infected individuals, some of which are viral and fungal. Acyclovir is an anti-viral active against herpes simplex virus type 1 and type 2, varicella-zoster virus, Epstein-Barr virus and the cytomegalovirus (Hayden, 2001:1317). The anti-fungal drug, ketoconazole has activity against the majority of pathogenic fungi which include Candida species and Histoplasma capsulatum (Bennett, 2001:1301). It is appropriate to formulate a topical product containing both acyclovir and ketoconazole because viral and fungal cutaneous manifestations are regularly encountered in combination in HIV/AIDS infected individuals,. This combination topical product may be useful in the treatment of viral and fungal opportunistic skin manifestations. Curing these skin lesions may also assist to improve the state of mind and wellbeing of infected individuals. The skin, however, acts as a barrier against diffusion of substances through the underlying tissue. The main problem in transdermal and dermal delivery of actives is to overcome the stratum corneum, the skin's natural barrier (Menon, 2002:4). The Pheroid™ delivery system can promote the absorption and increase the efficacy of a selection of active ingredients in dermatological preparations (Grobler et al., 2008:284). The aim of this study was to formulate a stable semi-solid product containing Pheroid™ to determine whether Pheroid™ technology would enhance the flux and/or delivery of acyclovir and ketoconazole to the epidermal and dermal layers of the skin. In vitro studies and tape stripping were used to determine the effect that the Pheroid™ delivery system had on skin permeation of acyclovir and ketoconazole in semi-solid formulations. The formulae containing no Pheroid™ were used as a control against which the efficacy of the formulations containing Pheroid™ was measured. The stability of the formulated semi-solid products was examined over a period of 6 months according to the International Conference of Harmonisation (ICH) Tripartite Guidelines (2003) and the Medicines control council (MCC) of South Africa (2006). The formulated products were stored at three different temperatures. The stability tests included the assay of the actives and other attributes in the formulation, pH, viscosity, mass loss and particle size observation. These tests were conducted at 0, 1, 2, 3 and 6 months. The results demonstrated that the transdermal flux, epidermal and dermal penetration of acyclovir was enhanced by the Pheroid™ cream formulation. Ketoconazole's transdermal flux as well as delivery to the epidermal and dermal layers of the skin was improved by the Pheroid™ emulgel formula. The topical delivery of ketoconazole and acyclovir was thus enhanced by Pheroid™ technology. The Pheroid™ formulations, however, did not meet the requirements for stability according to the ICH and MCC.
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