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
Racemic mixture of two enantiomers with different pharmaeokinetic and pharmacodynamic propeies is seen in - 
Select and explain. 
A. Dilantin, B. Digoxin, C. Verapamil, D. Octreotide
C: Verapamil
Answer: C: Verapamil 
Explanation: Ans. is 'c' i.e., Verapamil " Verapamil is prescribed as a racemate, L-Verapamil is a more potent calcium channel blocker than is dverapamil. However with oral therapy, the 1-enantiomer undergoes more extensive first - pass hepatic metabolism. For this reason, a given concentration of verapamil prolongs the PR interval to a greater extent when the drug is administered intravenously (where concentrations of the 1-and d-enantiomers are equivalent) than when it is administered orally."