Chlorpromazine is erratically absorbed from the gastro-intestinal tract and is also subject to variations from one individual to another. In addition when given orally it gets metabolised in the gut wall and the liver to certain extent leading to low blood concentrations. Hence, it is very difficult to determine the exact blood bio availability of oral v/s injectable forms. The dosage also varies from one individual to another and from one indication to another. Generally the dose is 25mg three times daily but can go up to 100mg three times daily or even higher in psychotic cases. The total daily dose must not exceed 600 to 800mg.