Provided herein is a method of treating a central nervous system disorder in a patient in need thereof, wherein the central nervous system disorder is selected from schizophrenia, Alzheimer's disease, Huntington's disease, Parkinson's disease, and Lewy Body dementia. The method comprises orally administering an initial dose of between 75 mg and 300 mg xanomeline and an initial dose of between 20 mg and 200 mg trospium chloride to the patient during a 24-hour period. Provided that the patient tolerates said administration, an increased dose of trospium chloride and an increased dose of xanomeline are orally administering to the patient, wherein the increased dose of trospium chloride is greater than the initial dose of the trospium chloride, and wherein the increased dose of xanomeline is greater than the initial dose of the xanomeline.