Calcium channel blocker with maximum effect on conduction in hea is:
Verapamil is phenylalkylamine which depresses the SA node and slows AV conduction. Others are less potent. But verapamil can cause constipation It is class 4 antiarrhythmic drug REF.Essentials of Pharmacology KD Tripathi 8th ed.
Phenylamine
Nifedipine
Diltiazem
Verapamil
Cardiovascular system