Coated microparticles for sustained-release of an active pharmaceutical ingredient after parenteral administration, and methods of producing such coated microparticles, are provided. The coated microparticles comprise core particles of an active pharmaceutical ingredient and a first polymeric coating on the core particles. The first polymeric coating is permeable to the active pharmaceutical ingredient forms a saturated solution within the coated microparticle, resulting in pseudo-zero-sustained release period. A second polymeric coating can be employed to add mechanical support or as a rate-controlling element.
