An Experimental Design to Evaluate the Effects of Process and Formulation on the Viability and Efficacy of L. reuteri Enteric-Coated Pellets in a Rat Model with Colitis.

Abstract

The efficacy of probiotic products depends on their viability throughout production, storage, and oral administration. This study optimized the formulation and processing of enteric-coated Lactobacillus reuteri (L. reuteri) pellets produced through extrusion-spheronization and fluidized-bed coating, employing a design of experiments (DOE) methodology. The ideal formulation consisted of 25% microcrystalline cellulose (MCC) and a 2:1 ratio of lactose to mannitol, satisfying criteria for disintegration, friability, and in vitro viability. The enteric coating process was refined using a coating percentage (X) of 9% Eudragit&#xae; L 100-55, a pump rate (X) of 10%, and an inlet temperature (X) of 45 &#xb0;C, resulting in a desirability of 0.993 for the prediction. The responses obtained from I-optimal design, a response surface methodology (RSM), were the viability of probiotics after the coating process (Y) and after 2 h at pH 2 (Y), both aligned with the applied mathematical model (p-value&#x2009;<&#x2009;0.0001). The storage stability of the final formulation for 6 months indicated that 2-4 &#xb0;C was the optimal temperature for preserving probiotics, while storage at room temperature (RT) caused a two-log reduction, although counts remained within the effective probiotic dose (-CFU/g per day). Macroscopic and microscopic study of colitis rats demonstrated the optimized formulation totally alleviated symptoms. The serum levels of inflammatory factors (interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF &#x3b1;)), as well as superoxide dismutase (SOD), were comparable to those in the dexamethasone-treated group. These findings identify optimum formulation and process factors that enhance probiotic viability and efficacy in developing resilient L. reuteri products.