Study and development of microemulsion formulations to increase the permeability of acyclovir

Abstract

The purpose of this study was to improve the permeability of acyclovir (ACV) by developing a water-in-oil microemulsion, since it is an important factor that influences the oral absorption and, consequently, the oral bioavailability of drugs. Pseudoternary phase diagrams (PTPD) were constructed to identify the regions for obtaining microemulsions (ME). From the region of fluid transparent systems, five ME were chosen to evaluate the effect on ACV permeability by using two-compartment horizontal Franz diffusion cells, using a bio-mimetic artificial membrane, which simulates the typical lipophilic characteristics of the biological membranes. The characterization of ME was carried out by PTPD, conductivity determination and Nuclear Magnetic Resonance studies. The formulation that showed the higher incorporation of ACV (81.57 mg/ml) consisted of 13.3% Polysorbate 80, 13.3% ethanol, 6.6% ginger oil and 66% water. An increase in ACV permeability was observed, reaching an apparent permeability coefficient of 1.99.10−6 cm/s, corresponding to a fraction of human absorbed dose of 99.97%, according to the correlation previously established by our research group. These results indicated the ability of ME to improve the permeability of ACV, representing a system with the potential to improve the efficacy of ACV in oral administrated pharmaceutical formulation.