Nonionic microemulsions for oral and transdermal delivery of gentamicin

Gentamicin sulfate (GS) is used usually as intravenous or intramuscular solution because of its poor oral bioavailability. However, the intravenous administration is associated with pain and needs some skills. In this study, five nonionic microemulsions (MEs) for oral and transdermal application were developed using nonionic surfactants. The MEs were characterized for their droplets sizes and rheological properties. Moreover, GS encapsulation in the MEs was studied using Fourier Transform Infrared Spectroscopy (FTIR). The transdermal release was evaluated through rat's skin using Franz diffusion cell. Furthermore, one of these formulations was chosen for oral bioavailability studies in rats in comparison to an aqueous solution of GS. These MEs complied with the colloidal properties. Also, FTIR was used successfully to prove the encapsulation of GS and alignment of the surrounding surfactants in the MEs. The best transdermal flux of MEs was 1.892 mg/cm2*h. The same ME showed a relative bioavailability of 239.7 % in comparison to the oral solution.