Niosomes are the non-ionic surfactant vesicles. Tenofovir disoproxil fumarate (TDF), an antiviral drug loaded niosomes which formulated by conventional thin film hydration technique with different molar ratios of surfactant: cholesterol (CHOL): dicetyl phosphate (DCP) as 2.5:1:0.1, 2:1:0.1, 1.5:1:0.1, 1:1:0.1 and 1:1.5:0.1； with two grades of different non-ionic surfactants i.e., sorbitan monostearate (span 60) and polyoxyethylene sorbitan monostearate (tween 60). The surfactants were selected on the bases of their HLB values. Sorbitan monostearate is of lipophilic nature with HLB value of 4.7 and polyoxyethylene sorbitan monostearate is of hydrophilic nature with HLB value of 14.9. The formulated niosomes were characterized for different parameters such as particle size analysis, zeta potential, entrapment efficiency, in vitro release and in vivo studies. Niosomal vesicles formulated with both the surfactants were found spherical in shape, ranging 5.70 μm to 8.55 μm in size. Zeta potential of the vesicles was found in range of -22 to -61. Vesicles with 1:1:0.1 ratios of surfactant: cholesterol: dicetyl phosphate； with both grades of surfactants were found to have higher entrapment efficiencies, which were further selected for in vitro release studies. Vesicles formulated with sorbitan monostearate were found to have maximum drug release (99.091%) at the end of 24 hours and also followed zero order release kinetics. The results of in vivo studies of the selected batch revealed that the niosomal vesicles significantly enhanced the oral bioavailability of TDF in rats after a dose of 95 mg/kg. The average relative bioavailability of niosomal vesicles in relation with plane drug solution was found to be 2.58, indicates more than two fold increase in oral bioavailability of TDF. Mean residential time (MRT) was also found to be significantly increased reflects release retarding efficacy of the vesicles. In conclusion niosomal vesicles could be promising delivery for TDF w
