nonDHP

Non-dihydropyridine calcium channel blockers, often abbreviated as nonDHP CCBs, are a subclass of calcium channel blocking drugs that predominantly target the heart and, to a lesser extent, vascular smooth muscle. They contrast with dihydropyridine (DHP) CCBs, which are more vascular-selective.

They block L-type voltage-gated calcium channels (Cav1.2) in cardiac nodal tissue and myocardium, reducing calcium entry. This leads to slowed conduction through the atrioventricular node, decreased heart rate, and reduced myocardial contractility, along with some vasodilation.

Most are hepatically metabolized, with varying half-lives. Common examples include verapamil and diltiazem. They can interact with beta-blockers, digoxin, and other agents that depress conduction, increasing the risk of bradycardia, AV block, and heart failure symptoms. Verapamil can cause constipation; edema is common with nonDHP and DHP. Grapefruit juice may inhibit metabolism of some CCBs.

Indications include hypertension, stable angina, vasospastic angina, and rate control in atrial fibrillation or flutter (predominantly with diltiazem or verapamil). They are used with caution in patients with left ventricular systolic dysfunction, heart block, or severe bradycardia. Combination with beta-blockers is common but requires monitoring for excessive bradycardia or conduction abnormalities.

Verapamil and diltiazem are the primary nonDHP agents. Bepridil was used historically but is rarely used due to proarrhythmic risk and interactions.