DEVELOPMENT AND IN VITRO CHARACTERIZATION OF POLYMER-BASED NASAL FORMULATIONS OF LEVOTHYROXINE
BACKGROUND. Hypothyroidism patients, unable to absorb oral levothyroxine rely on expensive and inconvenient intramuscular injections for life-time hormone replacement. OBJECTIVES: This project aimed to develop a non-invasive, less costly, and patient-friendly nasal delivery alternative using mucoadhesive polymers. METHODS: Nasal formulations were developed with carbopol, polycarbophil, chitosan, and hydroxypropyl methylcellulose (HPMC), respectively. The physicochemical properties and potential for nasal delivery were characterized. RESULTS: The formulation yield was high, with drug loading percentage of 72 -98% and mean particle size of less than 50 µm. The zeta-potential of the powder particles were electronegative and the differential calorimetric analysis and X-ray powder diffraction confirmed drug-polymer integration. The in vitro release studies demonstrated sustained levothyroxine release from the polymers over an extended period and their potential for nasal administration. CONCLUSIONS: Results of this study showed that carbopol, polycarbophil, chitosan, and HPMC can be used as sustained-release polymers for intranasal delivery of levothyroxine.