Dissolution and bioavailability of phenobarbital in solid dispersion with phosphatidylcholine

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery Systems
• Physical Pharmacy

Background:

• Phenobarbital (PB) is a widely used anticonvulsant drug.
• Improving the dissolution rate and bioavailability of poorly soluble drugs like PB is a significant challenge in pharmaceutical development.
• Solid dispersions offer a promising approach to enhance drug solubility and dissolution.

Purpose of the Study:

• To investigate the dissolution behavior of phenobarbital (PB) from solid dispersions with phosphatidylcholine (PC).
• To evaluate the impact of PB-PC solid dispersions on drug supersaturation and in vivo bioavailability.
• To determine the optimal formulation for enhanced phenobarbital delivery.

Main Methods:

• Preparation of phenobarbital-phosphatidylcholine (PB-PC) solid dispersions at various mole fractions.
• In vitro dissolution studies in pH 1.2 and pH 6.8 media.
• Assessment of supersaturation phenomena.
• In vivo pharmacokinetic studies in rabbits following oral administration.

Main Results:

• PB existed in an amorphous state in PB-PC solid dispersions for PB mole fractions below 0.75.
• Supersaturation was observed in both pH media, with the highest degree at a PB mole fraction of 0.25.
• Rapid and complete dissolution (>90% within 5 min) was achieved for PB-PC formulations.
• Oral administration in rabbits showed significantly higher maximum plasma concentration and faster time to maximum concentration for PB-PC compared to PB crystals.

Conclusions:

• Phenobarbital-phosphatidylcholine solid dispersions significantly enhance the dissolution rate of phenobarbital.
• The amorphous state and supersaturation effect contribute to improved drug absorption.
• PB-PC solid dispersions represent a viable strategy for improving phenobarbital bioavailability.