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 is not true about phenytoin ? 
Select and explain. 
A. It follows saturation kinetics, B. It causes hyperglycemia, C. It is teratogenic, D. It does not block insulin release
D: It does not block insulin release
Answer: D: It does not block insulin release 
Explanation: Ans. is 'd' i.e., It does not block insulin release Phenytoin inhibits insulin release which results in hyperglycemia. Phenytoin follows saturation kinetics i.e. at lower concentrations it has first order kinetic, whereas at higher concentrations kinetics becomes zero order due to saturation of metabolic pathways. Phenytoin is a known teratogen, produces fetal hydantoin syndrome.