Controlled-release hydrophilic tablets for individualized theophylline therapy

Area of Science:

• Pharmaceutical Technology
• Pharmacokinetics
• Drug Delivery Systems

Background:

• Theophylline is a critical drug requiring precise dosing to maintain therapeutic efficacy and avoid toxicity.
• Controlled-release (CR) formulations aim to provide consistent drug levels, but individual patient variability necessitates personalized dosing strategies.

Purpose of the Study:

• To develop and evaluate directly compressible controlled-release theophylline tablet formulations.
• To utilize a pharmacokinetic simulation model for individualizing theophylline therapy based on in vitro release data.

Main Methods:

• Preparation of CR theophylline tablets using various grades of Methocels, focusing on non-zero-order release kinetics.
• Development of a pharmacokinetic simulation model using STELLA II software.
• Simulation of plasma concentration-time (C,t) profiles using in vitro release data and published patient pharmacokinetic parameters (clearance, volume of distribution).

Main Results:

• Simulations indicated that CR theophylline formulations with low-viscosity Methocels (E4, K4, K4CR) achieved average steady-state concentrations within the therapeutic range (10-20 µg/mL).
• High-viscosity Methocels (E10CR, K15, K15CR) resulted in subtherapeutic theophylline concentrations, deeming them unsuitable for individualization.
• The pharmacokinetic simulation model successfully predicted in vivo C,t profiles despite non-zero-order drug release.

Conclusions:

• Pharmacokinetic simulation is a valuable tool for predicting in vivo drug behavior and individualizing therapy with CR formulations.
• Low-viscosity Methocel grades are suitable for developing CR theophylline tablets for personalized therapy.
• The study demonstrates the utility of in vitro-in silico approaches for optimizing drug delivery and patient treatment.