The research proposes the design of a model predictive control (MPC) for automatic drug dosing to regulate high blood pressure and urine production rate in an elderly patient. Combining hydrochlorothiazide and oxybutynin is commonly used for regulation of blood pressure in elderly patients. The patient’s model tries to captures the responses to the drugs as the blood pressure and urine production rates attains their various set-points. Hence, this research aims at improving the control scheme which ensured that these two physiological variables are regulated. Simulation was done in MATLAB/Simulink environment with the use of MPC Toolbox, and the controlled variables were constrained to operate at 80mmHg for blood pressure and between 24-49 ml/kg/hr for urine production rate respectively while the manipulated variables remained unconstrained. From the simulation results, the MPC controller achieved good set-point tracking and disturbance rejection, which is an indication of a healthy level of regulation within acceptable tolerances.