Preparation and characterization of PLGA particles for subcutaneous controlled drug release by membrane emulsification
G. Gasparini
S.R. Kosvintsev
Michael T. Stillwell
Richard Holdich
2134/3364
https://repository.lboro.ac.uk/articles/journal_contribution/Preparation_and_characterization_of_PLGA_particles_for_subcutaneous_controlled_drug_release_by_membrane_emulsification/9242048
Uniformly sized microparticles of poly(DL, lactic-co-glycolic) (PLGA) acid, with controllable
median diameters within the size range 40 to 140 microns, were successfully prepared by
membrane emulsification of an oil phase injected into an aqueous phase, followed by solvent
removal. Initially, simple particles were produced as an oil-in-water emulsion, where
dichloromethane (DCM) and PLGA were the oil phase and water with stabiliser was the
continuous phase. The oil was injected into the aqueous phase through an array type
microporous membrane, which has very regular pores equally spaced apart, and two different
pore sizes were used: 20 and 40 microns in diameter. Shear was provided at the membrane
surface, causing the drops to detach, by a simple paddle stirrer rotating above the membrane.
Further tests involved the production of a primary water-in-oil emulsion, using a mechanical
homogeniser, which was then subsequently injected into a water phase through the
microporous membrane to form a water-in-oil-in-water emulsion. These tests used a water
soluble model drug (blue dextran) and encapsulation efficiencies of up to 100% were obtained
for concentrations of 15% PLGA dissolved in the DCM and injected through a 40 micron
membrane.
Solidification of the PLGA particles followed by removal of the DCM through the surrounding
aqueous continuous phase. Different PLGA concentrations, particle size and osmotic
pressures were considered in order to find their effect on encapsulation efficiency. Osmotic
pressure was varied by changing the salt concentration in the external aqueous phase whilst
maintaining a constant internal aqueous phase salt concentration. Osmotic pressure was
found to be a significant factor on the resulting particle structure, for the tests conducted at
lower PLGA concentrations (10 and 5% PLGA). The PLGA concentration and particle size
distribution influence the time to complete the solidification stage and a slow solidification,
formed by stirring gently overnight, provided the most monosized particles and highest
encapsulation efficiency.
2008-06-04 10:12:23
PLGA
Membrane emulsification
Microparticle
Osmotic pressure
Encapsulation efficiency
Chemical Engineering not elsewhere classified