Development and Characterization of Thermosensitive intranasal Gel Containing Paliperidone Loaded Microspheres

Purpose: The objective of the present investigation was to fabricate a thermosensitive gel containing paliperidone loaded microspheres for the treatment of schizophrenia for brain delivery through nasal route. Incorporation of drug in to microspheres and then in to gel should increase the duration of release and nasal duration time respectively. Material and Method: Ethyl cellulose microspheres containing paliperidone palmitate were prepared by emulsification of ethyl acetate dispersion containing polymer and drug with aqueous external phase containing polysorbate 80. Amount of ethyl cellulose and polysorbate 80 were identified as critical formulation variables influencing the drug release at critical time points, percentage yield and particle size. These factors were studied using 2 factors and 3 level face centered factorial design using Design Expert®. Drug-excipient compatibility was ascertained using FTIR analysis. The paliperidone microspheres were then incorporated in to Pluronic F127 and HPMC gel having required thermo sensitive and muco adhesive properties. Gel containing microspheres was subjected to Ex vivo permeation study, irritation study using sheep nasal mucosa and pharmacodynamic study (spontaneous motor activity in mice). Results: Microspheres that could sustain the drug release up to 8 hours were developed. Thermoreversible gel having required thermo sensitive and muco adhesive properties was developed. The Ex vivo permeation study and pharm a codynamic study of the drug loaded microsphere containing gel confirmed the release up to 8 hours. The histopathology study showed absence of irritation on sheep nasal mucosa. Conclusion: Paliperidone palmitate loaded microspheres containing gel could prolong and target the drug release to brain and therefore give prolonged and intense action.