In-vitro dissolution behavior of some sustained-release theophylline dosage forms

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery Systems
• Physical Chemistry

Background:

• Sustained-release (SR) theophylline preparations are crucial for managing respiratory conditions.
• Understanding in-vitro dissolution is key to predicting in-vivo performance and ensuring therapeutic efficacy.
• The influence of external factors like pH and apparatus on dissolution profiles requires detailed investigation.

Purpose of the Study:

• To evaluate the in-vitro dissolution of six commercial theophylline SR preparations.
• To investigate the impact of pH and rotating speed on the dissolution rates.
• To characterize the surface and textural changes of SR products during dissolution and determine release mechanisms.

Main Methods:

• In-vitro dissolution testing using rotating basket and rotating bottle apparatus.
• Scanning electron microscopy (SEM) for surface and textural analysis.
• Comparative analysis of dissolution profiles across different pH conditions and rotating speeds.

Main Results:

• Dissolution behavior was found to be pH-dependent and varied among the SR products.
• The rotating bottle method showed limitations, particularly for matrix-type SR tablets due to adherence.
• Three distinct release mechanisms were identified: Fickian, non-Fickian, and zero-order transport.

Conclusions:

• The choice of dissolution apparatus and pH conditions significantly impacts the evaluation of theophylline SR products.
• Different theophylline SR formulations exhibit unique release kinetics, necessitating tailored assessment methods.
• SEM analysis provides valuable insights into the physical transformations governing drug release from SR systems.