A unit dosage form, such as a capsule or the like, for delivering a skeletal muscle relaxant, such as cyclobenzaprine hydrochloride, into the body in an extended or sustained release fashion comprising one or more populations of drug-containing particles (beads, pellets, granules, etc.) is disclosed along with a method of preparation therefor. The dosage form comprises active core particles which are individually surrounded by a water insoluble polymer coating which lacks plasticizer.
