Physical Characterization and Dissolution Properties of Verapamil. HCI Coprecipitates.

Area of Science:

• Pharmaceutical Sciences
• Materials Science

Background:

• Verapamil hydrochloride is a widely used calcium channel blocker.
• Developing stable solid dispersions is crucial for improving drug bioavailability and dissolution.
• Solvent-evaporation is a common technique for preparing solid dispersions.

Purpose of the Study:

• To prepare verapamil hydrochloride coprecipitates using different polymers.
• To investigate the effect of polymer ratios on drug release kinetics.
• To evaluate the physical and chemical stability of the prepared solid dispersions.

Main Methods:

• Solid dispersions were prepared using solvent-evaporation with ethylcellulose, hydroxypropyl cellulose, and hydroxypropyl methylcellulose phthalate (HP 55).
• Dissolution behavior was assessed in various pH buffers over 24 hours.
• Drug release kinetics were analyzed using common models, with Higuchi's equation identified as the best fit.
• Physical characterization included X-ray diffractometry, IR spectrophotometry, and DTA studies.
• Stability was evaluated through nine-month real-time studies.

Main Results:

• Drug release rate was significantly influenced by the polymer ratio in the coprecipitates.
• The diffusion model best described the drug release mechanism.
• Dissolution rate increased with a higher proportion of HP 55.
• Prepared coprecipitates were X-ray amorphous and remained stable over nine months, showing no significant changes in physical or chemical properties.
• Dissolution rates remained consistent during stability testing, indicating the stability of the amorphous drug phase.

Conclusions:

• The ratio of polymers, particularly HP 55, critically affects verapamil hydrochloride dissolution from solid dispersions.
• The prepared solid dispersions exhibit good physical and chemical stability, ensuring consistent drug release over time.
• The solvent-evaporation technique is effective for creating stable, amorphous verapamil hydrochloride solid dispersions with enhanced dissolution properties.