the present invention relates to microparticles containing an active principle against malaria , such as primaquine , one of its amino acid derivatives , or their conjugates with a hepatotropic vector or their pharmaceutically acceptable salts , and a biocompatible and biodegradable polymer controlling the kinetics of release of the active principle , like polylactide . the invention also relates to pharmaceutical compositions comprising microcapsules according to the invention . lastly , the invention relates to processes for the preparation of microparticles as mentioned above , the processes comprising : dissolving the polymer in a volatile solvent , adding to this solution the active principle and possibly a substance regulating the size of the microparticles , and at the end of evaporation , recovering the microparticles by centrifugation and filtration .