Pharmaceutical compositions of metabotropic glutamate 5 receptor (mGlu5) antagonists or a pharmacologically acceptable salt thereof are disclosed. The compositions contain the therapeutic active compound with non-ionic polymer and ionic polymer, binder and fillers in either matrix pellet, matrix tablet or coated pellets. The compositions provide a p H-independent in vitro release profile with NMT 70 % in one hour, NMT 85 % in 4 hour, and NLT 80 % in 8 hours. The compositions are useful for the treatment of CNS disorders, such as Treatment- Resistant Depression (TRD) and Fragile X Syndrome.