Sustained release oral dosage forms of an r-baclofen prodrug

594648 Disclosed herein is an oral tablet dosage form comprising a tablet and a coating, the tablet comprising: 3 wt-% to 20 wt-% (3R)-4-{ [(1S)-2-methyl-1-(2-methylpropanoyloxy)propoxy) carbonylamino} -3-(4-chlorophenyl)butanoic acid or a pharmaceutically acceptable salt thereof; 15 wt-% to 40 wt-% microcrystalline cellulose; 15 wt-% to 40 wt-% hydroxypropylmethyl cellulose; 3 wt-% to 30 wt-% of a release rate-controlling polymer; and dibasic calcium phosphate dihydrate or dibasic calcium phosphate anhydrous in an amount selected from 19 wt-% to 22 wt-% and 23 wt-% to 33 wt-%; based on the total weight of the dosage form; wherein the release-rate controlling polymer is a poly( ethylacrylate, methyl methacrylate, trimethylammonioethyl methacrylate chloride) copolymer having 8.8% to 12.0% ammonio methacrylate units on a dry substance basis. Additionally disclosed is a method of preparing said oral table dosage form comprising compacting the dry blend formulation to provide an oral tablet dosage form.