Citric acid as a plasticizer for spray-dried microcapsules

Area of Science:

• Pharmaceutical Sciences
• Materials Science

Background:

• Cellulose polymers like sodium carboxymethylcellulose (NaCMC) and hydroxypropylmethylcellulose (HPMC) are used for drug delivery.
• Controlling drug release and particle morphology is crucial for effective pharmaceutical formulations.

Purpose of the Study:

• To investigate the effect of citric acid as a plasticizer on the spray-drying of theophylline-loaded NaCMC and HPMC microcapsules.
• To determine the optimal plasticizer concentration for enhanced drug release and spherical particle formation.

Main Methods:

• Aqueous spray-drying technique was employed to encapsulate theophylline.
• Citric acid was used as a plasticizer at varying concentrations.
• Film strength, drug crystal form (X-ray diffraction), particle size, and drug release (dissolution T50%) were analyzed.

Main Results:

• Film strength correlated directly with dissolution T50% values.
• Citric acid altered polymer-drug interactions and crystal morphology in HPMC and NaCMC films.
• Spherical NaCMC microcapsules formed with 20-30% w/w plasticizer.
• Increased HPMC plasticizer concentration led to larger particle sizes.
• A 30% w/w plasticizer concentration was optimal for both drug release and spherical particle formation.

Conclusions:

• Citric acid effectively modifies the properties of NaCMC and HPMC for spray-dried drug delivery systems.
• The study identified an optimal plasticizer concentration for achieving desired theophylline microcapsule characteristics.