Diltiazem.

Diltiazem belongs to a class of medications called calcium channel blockers. These medications block the transport of calcium into the smooth muscle cells lining the coronary arteries and other arteries of the body. Since calcium is important in muscle contraction, blocking calcium transport relaxes artery muscles and dilates coronary arteries and other arteries of the body. By relaxing coronary arteries, diltiazem is useful in treating and preventing chest pain (angina) resulting from coronary artery spasm. Relaxing the muscles lining the arteries of the rest of the body lowers blood pressure, which reduces the burden on the heart as it pumps blood to the body. Reducing heart burden lessens the heart muscle's demand for oxygen, and further helps to prevent angina in patients with coronary artery disease.

How should I take this medicine?

Take diltiazem tablets by mouth. Follow the directions on the prescription label. Swallow the tablets with a drink of water. Take diltiazem tablets on an empty stomach, at least 1 hour before or 2 hours after food. Do not significantly increase grapefruit juice intake while taking this drug, or avoid grapefruit juice if possible. Take your doses at regular intervals. Do not take your medicine more often then directed. Do not stop taking except on your prescriber's advice.

What special precautions should I follow?

Before taking diltiazem,

* tell your doctor and pharmacist if you are allergic to diltiazem or any other drugs.
* tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially heart and blood pressure medications such as beta-blockers, digoxin (Lanoxin), quinidine (Quinaglute, Quinidex), and diuretics (water pills); carbamazepine (Tegretol); cimetidine (Tagamet); cyclosporine (Neoral, Sandimmune); fentanyl (Duragesic); medications to treat depression; medications to treat glaucoma (increased pressure in the eye); theophylline; and vitamins.
* tell your doctor if you have or have ever had heart, liver, or kidney disease.
* tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking diltiazem, call your doctor.
* if you are having surgery, including dental surgery, tell your doctor or dentist that you are taking diltiazem.

Drug Interactions

Diltiazem slows heart electrical conduction, and can cause a dangerously slow heart rate in patients with existing electrical conduction disease of the heart. Concurrent use of diltiazem with a beta blocker (another class of medications that slow heart rate) can occasionally cause profound heart slowing. Diltiazem can aggravate heart failure and cause excessive lowering of blood pressure.

Administration of diltiazem with digoxin can increase digoxin blood levels. Therefore, blood levels of digoxin are usually monitored to avoid toxicity. 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. Concurrent administration of cimetidine (Tagamet) interferes with the liver breakdown of diltiazem, and significantly increases diltiazem blood levels. Therefore, cautious dosing is necessary when both medications are administered. Safety in children has not been established.

Pregnancy

Generally, diltiazem is avoided in pregnancy.

Nursing Mothers

Generally, diltiazem is avoided in nursing mothers.

Side Effects

Side effects are generally mild and transient. Diltiazem can cause difficulty breathing or wheezing as a result of worsening heart failure. It can cause dizziness, weakness or fainting because of slow heart rate or low blood pressure. Other side effects include swelling of the lower extremities, rash, headache, and constipation. Diltiazem can also cause mildly abnormal liver tests that are generally reversible with discontinuation of the medication.

References:
1.http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a684027.html
2.http://www.medicinenet.com/diltiazem/article.htm
3.http://www.drugdigest.org/DD/DVH/Uses/0,3915,206%7CDiltiazem,00.html