A novel solid dosage form of rifampicin and isoniazid with improved functionality

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery Systems
• Medicinal Chemistry

Background:

• Rifampicin is prone to degradation in acidic environments, complicating its formulation.
• Simultaneous administration of rifampicin and isoniazid requires careful consideration of drug-drug interactions and release profiles.
• Existing formulations may not adequately protect rifampicin from degradation or achieve targeted drug release.

Purpose of the Study:

• To develop a novel dosage form for rifampicin and isoniazid.
• To minimize rifampicin degradation in acidic conditions.
• To modulate the release of rifampicin in the stomach and isoniazid in the intestine.

Main Methods:

• Gastroretentive tablets of rifampicin were prepared using hydroxypropyl methylcellulose, calcium carbonate, and polyethylene glycol 4000.
• Enteric-coated capsules of isoniazid were developed.
• A combination dosage form was created by encapsulating rifampicin tablets and isoniazid capsules.
• In vitro drug release and degradation studies were conducted using modified apparatus.

Main Results:

• The novel dosage form demonstrated controlled release of rifampicin over 4 hours with zero-order kinetics.
• Over 90% of isoniazid was released within 30 minutes in an alkaline medium.
• Rifampicin degradation was significantly reduced (3.6%-4.8% over 4 hours) compared to immediate-release formulations.
• Minimized physical contact and controlled release protected rifampicin from degradation in acidic media.

Conclusions:

• The developed novel dosage form effectively minimizes rifampicin degradation.
• This formulation allows for targeted release of rifampicin in the stomach and isoniazid in the intestine.
• The strategy of controlled release and physical separation alleviates rifampicin degradation issues.