The present study compares two methods of preparation of microparticles of
3,4-diaminopyridine (3,4-DAP) for the treatment for
multiple sclerosis and Lambert-Eaton myasthenia syndrome.
Poly( epsilon -caprolactone) microparticles were prepared with a
solvent-evaporation W/O method. The 3,4-DAP was dispersed in
dichloromethane, leading to a
suspension. The dispersion and the solidification of the
dichloromethane droplets in an aqueous phase have led to microparticles of 55.3+/-34.7 microm. The incorporation of the
drug by milligram of
powder was very low (1.91 micrograms/mg) and the scanning electron microscopy (SEM) did not show any crystal but marks of dissolved crystals were observed on the polymeric surface. EudragitRS
microspheres containing 3,4-DAP were prepared by a
solvent-evaporation technique using light
mineral oil as continuous phase. The
drug and the
polymer were completely dissolved in an
acetone solution, used as discontinuous phase. This formulation have led to a higher incorporation of the
drug (88.25 micrograms/mg). The particle size was 91.8+/-44.3 microm. The observation, by SEM, shows many crystals on the surface and inside the microparticles. A slow-release of the
drug in a
phosphate buffer pH 7.4 was observed (50% in 60 min and about 70% in 4 h).