rate of infusion rate of infusion in pharmacokinetics, the rate of infusion (or dosing rate) refers not just to the rate at which a drug is administered, but the desired rate at which a drug should be administered to achieve a steady state of a fixed dose which has been demonstrated to be therapeutically effective. abbreviations include kin, k0, or r0. it can be calculated as the steady-state concentration in the plasma multiplied by the clearance: k i n = c s s ⋅ c l =c_\cdot cl}