Nanoemulsion-based intranasal drug delivery system of saquinavir mesylate for brain targeting

The central nervous system (CNS) is an immunological privileged sanctuary site-providing reservoir for HIV-1 virus. Current anti-HIV drugs, although effective in reducing plasma viral levels, cannot eradicate the virus completely from the body. The low permeability of anti-HIV drugs across the blood-brain barrier (BBB) leads to insufficient delivery. Therefore, developing a novel approaches enhancing the CNS delivery of anti-HIV drugs are required for the treatment of neuro-AIDS. The aim of this study was to develop intranasal nanoemulsion (NE) for enhanced bioavailability and CNS targeting of saquinavir mesylate (SQVM). SQVM is a protease inhibitor which is a poorly soluble drug widely used as antiretroviral drug, with oral bioavailability is about 4%. The spontaneous emulsification method was used to prepare drug-loaded o/w nanoemulsion, which was characterized by droplet size, zeta potential, pH, drug content. Moreover, ex-vivo permeation studies were performed using sheep nasal mucosa. The optimized NE showed a significant increase in drug permeation rate compared to the plain drug suspension (PDS). Cilia toxicity study on sheep nasal mucosa showed no significant adverse effect of SQVM-loaded NE. Results of in vivo biodistribution studies show higher drug concentration in brain after intranasal administration of NE than intravenous delivered PDS. The higher percentage of drug targeting efficiency (% DTE) and nose-to-brain drug direct transport percentage (% DTP) for optimized NE indicated effective CNS targeting of SQVM via intranasal route. Gamma scintigraphy imaging of the rat brain conclusively demonstrated transport of drug in the CNS at larger extent after intranasal administration as NE.