Development and Optimization of Myricetin Loaded Inhalable Microsphere to Treat COPD

To develop and optimize myricetin-loaded inhalable microspheres using ionotropic gelation technique for sustained pulmonary delivery in Chronic Obstructive Pulmonary Disease (COPD) treatment.

Myricetin-loaded microspheres were prepared using varying concentrations of gellan gum and sodium alginate through a 3² full factorial design. Formulations were characterized for physicochemical properties, in vitro release, aerodynamic performance using twin impinger, and stability. The optimized formulation was evaluated for bronchodilatory activity using histamine-induced contraction of goat tracheal chain model and compared with theophylline anhydrous.

The optimized formulation (DF4) exhibited spherical morphology with ideal particle size for pulmonary delivery (7.72 μm), high entrapment efficiency (72.84%), and negative zeta potential ensuring colloidal stability. This formulation demonstrated excellent aerodynamic properties (FPF 31.71%), sustained drug release over 12 h, and remarkable stability over 6 months under both accelerated and real-time storage conditions. The formulation showed significant bronchodilatory activity with 63.47% relaxation at 25 μg/ml, achieving approximately 80.8% efficacy compared to theophylline anhydrous.

The optimized myricetin-loaded inhalable microspheres represent a promising pulmonary delivery system for COPD management, offering advantages of sustained drug release, improved lung deposition, and significant bronchodilatory effect. This formulation holds potential for reducing dosing frequency, enhancing patient compliance, and improving therapeutic outcomes in COPD patients, warranting further in vivo studies before clinical translation.