Diltiazem

Diltiazem is a member of the group of drugs known as benzothiazepines, which are a class of calcium channel blockers, used in the treatment of hypertension, angina pectoris, and some types of arrhythmia. It is also an effective preventive medication for migraine. It is a class 3 anti-anginal drug, and a class IV antiarrhythmic. It incites very minimal reflex sympathetic changes. It is based upon a 1,4-thiazepine ring.
Diltiazem is a potent vasodilator, increasing blood flow and variably decreasing the heart rate via strong depression of A-V node conduction. Its pharmacological activity is somewhat similar to verapamil.[1]
Diltiazem is metabolized by and acts as an inhibitor of the CYP3A4 enzyme.
Diltiazem is relatively contraindicated in the presence of sick sinus syndrome, atrioventricular node conduction disturbances, bradycardia, impaired left ventricle function, peripheral artery occlusive disease, chronic obstructive pulmonary disease, and Prinzmetal's angina.

Stable (exercise-induced) Angina. Diltiazem increases coronary blood flow and decreases myocardial oxygen consumption, secondary to decreased peripheral resistance, heart rate, and contractility.[3][4]
Variant Angina. Diltiazem is effective due to its direct effects on coronary dilation.
Unstable (preinfarction, crescendo) Angina. Diltiazem may be particularly effective if the underlying mechanism is vasospasm.
Supraventricular tachycardias. Diltiazem appears to be as effective as verapamil in treating reentrant supraventricular tachycardia.[5]
Atrial fibrillation or flutter.
Hypertension. Because of its vasodilatory effects, diltiazem is useful for treating hypertension. Calcium channel blockers are well-tolerated, and especially effective in treating low-renin hypertension.[6]