Phenytoin is a drug that follows zero order kinetics at high doses and first order kinetics at low doses. Suppose, 400 mg phenytoin is present in the body and its rate of elimination at this dose is 200 mg/hr, how much will remain in plasma after 2 hours?

* We cannot predict because we don't know when it will sta following first order kinetics. Order of kinetics: FIRST ORDER ZERO ORDER Constant fraction of drug is eliminated Constant amount is eliminated Rate of elimination is directly propoional to plasma concentration Rate of elimination is constant Clearance is constant Clearance is inversely propoional to plasma concentration Half life is constant Half life is directly propoional to plasma concentration.