A novel method of preparing PLGA microcapsules utilizing methylethyl ketone

Area of Science:

• Polymer Science
• Materials Science
• Pharmaceutical Technology

Background:

• Traditional microencapsulation often uses dichloromethane, a solvent with safety concerns.
• Developing safer alternatives for poly(d,l-lactide-co-glycolide) (PLGA) microcapsule preparation is crucial for pharmaceutical applications.

Purpose of the Study:

• To develop a solvent extraction process using methylethyl ketone (MEK) as a safer alternative to dichloromethane for preparing PLGA microcapsules.
• To investigate the encapsulation efficiency and morphology of microcapsules prepared using MEK.

Main Methods:

• PLGA and progesterone were dissolved in MEK to form a dispersed phase.
• This phase was emulsified in a MEK-saturated aqueous phase (W1) to create a transient oil-in-water (O/W1) emulsion.
• The emulsion was transferred to water (W2) to extract MEK from the polymeric droplets.

Main Results:

• The solvent extraction process yielded progesterone encapsulation efficiencies between 60% and 77%.
• Encapsulation efficiency was influenced by the amount of MEK in W1 and the progesterone payload.
• Rapid MEK diffusion and water ingress resulted in the formation of hollow microcapsules, confirmed by SEM.

Conclusions:

• Water-immiscibility of the dispersed phase is not essential for successful PLGA microencapsulation using solvent extraction/evaporation.
• Controlling the initial MEK extraction rate and the formation of the primary transient O/W1 emulsion are critical for successful microencapsulation and determining microcapsule morphology.