This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Pharmacology, Subject name: Pharmacology
Percentage of drug existing as enantiomer is: 
Select and explain. 
A. <1%, B. 10%, C. >50%, D. 100%
C: >50%
Answer: C: >50% 
Explanation: Ans: c (>50%) Ref: Katzung, 10 ed, p. 4Due to chirality (stereoisomerism) more than half of all useful drugs exists as enantiomers.Other important properties:One of the enantiomers will be more potent than its mirror image. The potent enantiomer which is active at one type of receptor may not be active at another type.One of the enantiomers will be more susceptible to drug metabolizing enzymes than the other.