Niosome-based delivery systems for olanzapine: Formulation, characterisation, and kinetic evaluation

This study investigates the development and characterisation of niosome-based delivery systems for olanzapine, an antipsychotic drug. Niosomes were prepared using various grades of Span surfactants (Span 60, Span 40, and Span 20) in combination with cholesterol at different ratios. The formulations were characterised in terms of particle size, polydispersity index, zeta potential, and encapsulation efficiency. Results showed an inverse relationship between surfactant hydrophilic-lipophilic balance (HLB) values and niosome size, with Span 60 producing the smallest vesicles. Optimal formulations were achieved with a 1:1 ratio of surfactant to cholesterol. Span 60 niosomes exhibited the highest encapsulation efficiency (up to 81 ± 2.5 %) and the most negative zeta potential, indicating superior stability. <i>In vitro</i> release studies demonstrated sustained release profiles for all niosomal formulations compared to the free drug, with Span 60 formulations showing the slowest release rates. Release kinetics analysis revealed a Fickian diffusion-controlled mechanism best described by the Korsmeyer-Peppas model. These findings suggest that niosomal formulations, particularly those based on Span 60, offer a promising approach for improving olanzapine delivery, potentially enhancing its bioavailability and therapeutic efficacy in the treatment of psychiatric disorders.