This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
All of the following drugs acts by blocking calcium channels except 
Select and explain. 
A. Dantrolene, B. Nicardipine, C. Diltiazem, D. Verapamil
A: Dantrolene
Answer: A: Dantrolene 
Explanation: Dantrolene is a directly acting skeletal muscle relaxant. It is used for treating malignant hypehermia. It is available as an injection All others are calcium channel blockers used in HTN REF.Essentials of Pharmacology KD Tripathi 8th ed.