An injectable intramuscular depot composition suitable for forming an in situ solid implant in a body, comprisinga drug which is paliperidone and/or its pharmaceutical acceptable salts in any combination thereof, a biocompatible copolymer based on lactic and glycolic acid having a monomer ratio of lactic to glycolic acid in the range from 50:50 and a DMSO solvent, wherein the composition releases the drug with an immediate onset of action and continuously for at least 8 weeks and wherein the composition has a pharmacokinetic profile in vivo suitable for the formulation to be administered each 8 weeks or even longer periods.
