This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Which of the following about phenytoin is true ? 
Select and explain. 
A. It follows zero order kinetics, B. Not an hepatic enzyme inducer, C. It is excreted unchanged in urine, D. It is not teratogenic
A: It follows zero order kinetics
Answer: A: It follows zero order kinetics 
Explanation: Ans. is 'a' i.e., It follows zero order kinetics Phenytoin is metabolized in liver by hydroxylation and glucuranide conjugation (option 'c' is incorrect) o This drug follows saturation kinetics (kinetics changes from first order to zero order within therapeutic concentrations) Phenytoin is an enzyme inducer and induces the metabolism of many drugs. Phenytoin is a known teratogenic and produces fetal hydantoin syndrome.