Preparation of polymeric microcapsules: formulation studies.

Area of Science:

• Materials Science
• Chemical Engineering
• Pharmaceutical Technology

Background:

• Air-filled microcapsules are prepared using oil-in-water emulsions with biodegradable polyesters.
• Previous work utilized human serum albumin as a surfactant.
• This study explores a new poly(ethylene glycol) (PEG) block copolymer as a surfactant replacement.

Purpose of the Study:

• To optimize the formulation of air-filled microcapsules for improved suspension and emulsion stability during production.
• To evaluate the efficacy of a novel PEG-based block copolymer as a surfactant.
• To investigate the impact of formulation parameters on microcapsule characteristics.

Main Methods:

• Factorial design was employed to study formulation parameters like mannitol, polymer, and surfactant concentrations, pH, and phase ratio.
• Ordinary least-square (OLS) and partial least-square regression (PLSR) were used for data analysis.
• Emulsion stability was assessed at 60°C.

Main Results:

• The PEG block copolymer proved to be a suitable alternative to human serum albumin.
• Emulsion stability at 60°C was significantly influenced by polymer and surfactant concentrations.
• Low polymer concentrations (< 5% w/v in (-)-camphene) yielded the highest microcapsule production.
• Mannitol addition enhanced freeze-drying protection, reducing cracks and shrinkage, and increasing suspension yield.

Conclusions:

• A novel PEG-based surfactant effectively replaces human serum albumin in air-filled microcapsule production.
• Optimized concentrations of polymer and surfactant are crucial for emulsion stability and microcapsule yield.
• Mannitol is a key excipient for improving freeze-drying stability and the quality of the final microcapsule product.