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Diltiazem (INN) () is a nondihydropyridines (non-DHP) calcium channel blocker used in the treatment of hypertension, angina pectoris, and some types of arrhythmia. It relaxes the smooth muscles in the walls of arteries, which opens (dilates) the arteries, allows blood to flow more easily, and lowers blood pressure. Additionally, it lowers blood pressure by acting on the heart itself to reduce the rate, strength, and conduction speed of each beat. It is also used off-label as an effective preventive medication for migraine. It is a class 3 antianginal drug, and a class IV antiarrhythmic. It is a common adulterant of cocaine seized in the UK, and has been found to reduce cocaine cravings in rats, indicating it may prolong the "high" (see below). Diltiazem is metabolized by and acts as an inhibitor of the CYP3A4 enzyme which can cause it to interact with a variety of other medications. ==Mechanism== 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, another nondihydropyridine (non-DHP) calcium channel blocker. Chemically, it is based upon a 1,4-thiazepine ring making it a benzothiazepine type calcium channel blocker. It is a vasodilator of coronary and peripheral vessels, which reduces peripheral resistance and afterload. Though not as potent as the dihydropyridine (DHP) calcium channel blockers. This results in minimal reflex sympathetic changes. Diltiazem has negative inotropic, chronotropic, and dromotropic effects. This means diltiazem causes a decrease in heart muscle contractility - how strong the beat is, lowering of heart rate - due to slowing of the sinoatrial node, and a slowing of conduction through the atrioventricular node - increasing the time needed for each beat. Each of these effects results in reduced oxygen consumption by the heart, reducing angina symptoms. These effects also reduce blood pressure by causing less blood to be pumped out. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「diltiazem」の詳細全文を読む スポンサード リンク
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