FORMULATION AND DEVELOPMENT OF RISPERIDONE LOADED NIOSOMES FOR IMPROVED BIOAVAILABILITY: IN VITRO AND IN VIVO STUDY

Risperidone is a well-known antipsychotic drug that is extensively employed in the treatment of schizophrenia and other psychotic disorders. Orally administered risperidone get metabolized by cytochrome P-450 enzymes into equipotent 9-hydroxy risperidone which have limited access to blood brain barrier (BBB). To overcome this issue niosomes containing risperidone were formulated, optimized and evaluated based on the assumption that non-ionic surfactant prevents the metabolism of risperidone by cytochrome P-450 enzymes that catalyzes the conversion of risperidone to its metabolite. Niosomes were prepared by sonication method and span 60 formulations exhibited the highest entrapment efficiency (92.83%) followed by span 40, span 80. span 20 and tweens of different grades. Vesicle size ranging from 180 nm to 388.9 nm exhibited lower PIN (0.171 to 0.437) and high zeta potential values (-20.4 mV to -50.6 mV). TEM showed that vesicles are spherical and FTIR and DSC studies revealed the absence of any potential incompatibility between the formulation ingredients. Niosomes exhibited in-vitro sustained release profile and followed Fickian diffusion mechanism. No significant change in general appearance, vesicle size and entrapment efficiency was observed for the formulations stored at refrigerated conditions (4 +/- 1 degrees C) and at room temperature (25 +/- 2 degrees C) for a period of 90 days. The niosomes were stable against solubilization action of bile salts (sodium desoxycholate). Ex-vivo studies revealed that both the flux and permeability coefficient was increased for niosomes with and without bile salts and enhancement ratio was almost 2-fold for niosomes without bile salts and 1.33-folds for niosomes containing bile salts. The relative bioavailability of niosomes prepared with bile salts was observed to be 108% in comparison to standard, whereas niosomes prepared without bile salts exhibited a higher bioavailability of 111%. It can be concluded that the developed niosomes offer better bioavailability of risperidone and this can be used for effective drug delivery.