Development of a controlled-release tofacitinib formulation using acid-sensitive pore-forming components for an osmotic drug delivery system

Acid-sensitive ingredient porosity osmotic drug delivery systems (AID) are a simplified and scalable alternative to conventional ODDS. In the current study, the tofacitinib-loaded AID formulation was optimized using an I-optimal mixture design. The three coating excipients examined as independent variables were cellulose acetate (X₁; 25.8-43.8 %), sodium bicarbonate (X₂; 20.0-30.0 %), and hydroxypropyl cellulose (X₃; 26.3-46.3 %). Response variables included cumulative drug release at 2 h (Y₁), 4 h (Y₂), and 8 h (Y₃), as well as the percentage of residual drug after 8 h (Y₄), which were analyzed using a quadratic model within the I-optimal framework. The coefficient of determination (R²) values for Y₁, Y₂, Y₃, and Y₄ were 0.79, 0.74, 0.55, and 0.48, respectively. The optimized AID exhibited zero-order drug release kinetics (R² = 0.9931), with a release rate constant (K₀) of 0.20 h⁻¹, indicating a consistent and controlled release profile throughout the evaluation period. Pharmacokinetic studies indicated no significant lag time for the AID, while Xeljanz® XR 11 mg exhibited an initial lag time of approximately 0.64 h, consistent with the characteristics of conventional ODDS technologies. Maximum plasma concentrations (C_max) were 75.7 ± 40.8 ng/mL for Xeljanz® XR 11 mg and 79.4 ± 37.1 ng/mL for AID. The areas under the plasma concentration-time curve were 610.0 ± 187.5 ng/mL for Xeljanz® XR 11 mg and 586.1 ± 210.5 ng/mL for AID. Times to maximum plasma concentration were 5 h for Xeljanz® XR 11 mg and 2 h for AID. Collectively, this modified approach reduces the initial lag time and allows for faster drug action.