Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD
GENERIC NAME: diltiazem
BRAND NAMES: Cardizem, Dilacor, Tiazac and several others
DRUG CLASS AND MECHANISM: Diltiazem is a drug that is used for
treating heart pain (angina), high blood pressure, and abnormal heart rhythms.
It belongs to a class of drugs called calcium channel blockers (CCBs),
which includes amlodipine (Norvasc), verapamil (Calan, Isoptin), nifedipine (Adalat, Procardia) as well as others. CCBs block the entry of calcium into muscle cells that make up the
heart and that surround the arteries. It is the entry of calcium into these
cells that causes the cells to contract, allowing the heart to pump blood, and
the arteries to narrow. By blocking the entry of calcium, diltiazem decreases
the force of contraction of the heart and its rate of contraction. It also
relaxes the muscles surrounding the arteries, allowing the arteries to widen
(dilate). In order to pump blood, the heart needs oxygen. The harder the heart
works, the more oxygen it requires. Angina occurs when the supply of oxygen to
the heart is inadequate for the amount of work the heart must do. By dilating
arteries, diltiazem reduces the pressure in the arteries into which the heart
must pump blood, and, as a result, the heart needs to work less and requires
less oxygen. By reducing the heart's need for oxygen, diltiazem relieves or
prevents angina. Dilation of the arteries also reduces blood pressure. The FDA
approved diltiazem in 1982.
PRESCRIPTION: Yes
GENERIC AVAILABLE: Yes
PREPARATIONS: Tablets (immediate release): 30, 60, 90, and 120 mg.
Tablets (extended release): 120, 180, 240, 300, 360, 420 mg. Capsules (extended
release): 60, 90, 120, 180, 240, 300, 360, 420 mg. Injection: 5 mg/ml. Powder
for injection: 25 mg.
STORAGE: Tablets, capsules and powder for injection should be stored
at room temperature, 15-30 C (59-86 F). Solution for injection should be stored
at 2-8 C (36-46 F).
PRESCRIBED FOR: Diltiazem is used for treating heart pain (angina),
high blood pressure, and abnormal heart rhythms such as atrial fibrillation,
atrial flutter and paroxysmal supraventricular tachycardia.
DOSING: Adult oral doses range between 120 and 480 mg daily. Immediate
release tablets are administered up to 4 times a day. Extended release
formulations are administered once daily at approximately the same time each day
and should not be crushed or chewed.
DRUG INTERACTIONS: Administration of diltiazem with digoxin
(Lanoxin) can
increase digoxin blood levels. Therefore, blood levels of digoxin usually are
monitored to avoid toxicity from digoxin. Similarly, concurrent administration
of diltiazem with an anti-seizure medication, carbamazepine (Tegretol), can
increase blood levels of the seizure medication, and occasionally lead to
toxicity. Diltiazem increases blood levels of lovastatin (Mevacor), atorvastatin
(Lipitor) and simvastatin (Zocor), possibly increasing the risk of adverse
effects. Diltiazem may increase blood levels of buspirone (Buspar),
midazolam
(Versed), triazolam (Halcion) and diazepam (Valium) by reducing their breakdown
and elimination from the body by the liver. This can lead to toxicity from these
drugs. Rifampin (Rifamate,
Rifadin,
Rimactane) reduces the effect of diltiazem by reducing its levels in blood
to undetectable levels.
PREGNANCY: There are no adequate studies of diltiazem in
pregnant
women.
NURSING MOTHERS: Diltiazem is excreted in
breast-milk. To avoid
adverse effects in the infant, diltiazem should not be taken while nursing.
SIDE EFFECTS: Side effects include constipation, nausea, headache,
rash, edema (swelling of the legs with fluid), low blood pressure, drowsiness,
and dizziness. Liver dysfunction and overgrowth of the gums also may occur.
Diltiazem can cause mildly abnormal liver tests that usually return to normal
with discontinuation of the medication. When diltiazem is given to individuals
with heart failure, symptoms of heart failure may worsen because these drugs
reduce the ability of the heart to pump blood. Like other drugs for high blood
pressure, diltiazem is associated with sexual dysfunction.
Last Editorial Review: 1/9/2009
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
- Calcium Channel Blockers - Establishes the medication calcium channel blockers (CCBs), which are drugs used for treating high blood pressure, angina, and abnormal heart rhythms like atrial fibrillation.
- High Blood Pressure - Learn about high blood pressure symptoms like headache, dizziness, shortness of breath, blurred vision and more. Causes, and normal blood pressure information is included.
- Angina - Learn about the causes and symptoms of angina like pressure, heaviness, tightening, squeezing, and aching across the chest. There are two types of angina, stable (the most common) and unstable.
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