Formulation and evaluation of microspheres-loaded capsule of duloxetine HCL by extrusion-spheronization techniques

The present Investigation focuses on the formulation; optimization and evaluation of a microsphere-loaded capsule containing Duloxetine HCl; aimed at enhancing its oral bioavailability and therapeutic efficacy. Duloxetine HCl; a selective serotonin and norepinephrine reuptake inhibitor (SNRI); exhibits limited water solubility and is unstable in acidic pH; leading to reduced absorption and erratic bioavailability. The goal was to develop a controlled-release multiparticulate dosage form to improve therapeutic efficacy and patient compliance. A series of formulations were prepared by varying the polymer type and drug-to-polymer ratios; and the process parameters were optimized with a particular focus on spheronization speed (fixed at 1200 rpm) and spheronization time. Optimization was guided by evaluating key parameters such as micromeritic properties (bulk density; tapped density; Carr’s index); particle size distribution; percentage yield; drug entrapment efficiency; and drug release. In vitro drug release studies were conducted over 12 hours to assess sustained-release behavior. Among the prepared batches; the formulation using Sodium Alginate in a 1:2 drug-to-polymer ratio demonstrated optimal performance; exhibiting high entrapment efficiency (above 85%); favorable spherical morphology; and sustained drug release following Higuchi diffusion kinetics. Surface morphology observed under Scanning Electron Microscopy (SEM) confirmed well-formed; discrete; and spherical microspheres. Among the various formulations; batch F6 demonstrated superior performance with excellent flow properties; high entrapment efficiency (85.4 %); and sustained drug release of 83.82% over 12 hours; indicating controlled release behavior. 

The study concludes that through systematic optimization of formulation and process parameters; natural polymer-based microspheres of Duloxetine Hydrochloride can be successfully developed for controlled oral delivery. Drug-to-polymer ratio demonstrated optimal performance; exhibiting high entrapment efficiency (above 85%); physicochemical compatibility using Fourier Transform Infrared Spectroscopy (FTIR); favorable spherical morphology; and sustained drug release following Higuchi diffusion kinetics. The study confirms that the developed microsphere-loaded capsule system offers a promising strategy for improving the solubility; stability; and controlled release of Duloxetine HCl; thereby potentially enhancing patient compliance and therapeutic outcomes.