Description: Diltiazem is a calcium channel blocker that relaxes the muscles of your heart and blood vessels.
Onset: 30-60 min (oral); 3 min (IV).
Duration: 1-3 hr (IV bolus).
Absorption: Rapidly and almost completely absorbed from the GI tract. Bioavailability: Approx 40%. Time to peak plasma concentration: Approx 3-8 hr (oral).
Distribution: Enters breast milk. Volume of distribution: 3-13 L/kg. Plasma protein binding: Approx 80%.
Metabolism: Undergoes extensive hepatic first-pass effect; by CYP3A4 isoenzyme into desacetyldiltiazem (as metabolites, approx 25-50% as potent as the parent compound).
Excretion: Via urine (approx 2-4% as unchanged drug, 6-7% as metabolites); bile (remaining metabolites). Half-life: Approx 3-8 hr.


Diltiazem is used to prevent chest pain (angina). It may help to increase your ability to exercise and decrease how often you may get angina attacks.

Diltiazem may also be used to control your heart rate if you have a fast/irregular heartbeat (such as atrial fibrillation). Long-acting forms of diltiazem may be used to treat high blood pressure.


Should not be given to patients with:

  • Sick sinus syndrome
  • Second or third degree AV block
  • Severe hypotension
  • Hypersensitivity to the drug
  • Acute myocardial infarction and pulmonary congestion

How to use diltiazem

  • Take this medication by mouth before meals and at bedtime as directed by your doctor, usually 3 to 4 times a day.
  • Swallow the tablets whole. Do not split, crush, or chew the tablets.

Use this medication regularly to get the most benefit from it.

Cardiac conduction:  Diltiazem may cause abnormally slow heart rates or second- or third- degree AV block.  Concomitant use of diltiazem with beta-blockers or digitalis may result in additive effects on cardiac conduction.

Congestive Heart failure: Worsening of congestive heart failure has been reported in patients with preexisting impairment of ventricular function. Experience with the use of diltiazem hydrochloride in combination with beta-blockers in patients with impaired ventricular function is limited. Caution should be exercised when using this combination.

Hypotension: Decreases in blood pressure associated with diltiazem hydrochloride therapy may occasionally result in symptomatic hypotension.

Acute hepatic injury: Mild elevations of transaminases with and without concomitant elevation in alkaline phosphatase and bilirubin have been observed in clinical studies. Such elevations were usually transient and frequently resolved even with continued diltiazem treatment.

Common side effects:

  • Dizziness,
  • lightheadedness,
  • weakness,
  • nausea,
  • flushing,
  • constipation, and
  • headache

To lower the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.

Tell your doctor immediately if any of these unlikely but serious side effects occur:

  • fainting,
  • slow/irregular/pounding/fast heartbeat,
  • swelling ankles/feet,
  • shortness of breath,
  • unusual tiredness,
  • unexplained/sudden weight gain,
  • mental/mood changes (such as depression, agitation),
  • unusual dreams

Tell your doctor immediately if any of these rare but very serious side effects occur:

  • severe stomach/abdominal pain,
  • dark urine,
  • persistent nausea/vomiting,
  • yellowing eyes/skin


  • Allergy: Before taking diltiazem, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies.
  • Medical conditions: Before using this medicine, consult your doctor or pharmacist if you have: certain types of heart rhythm problems (such as sick sinus syndrome/atrioventricular block unless you have a pacemaker).
  • Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver disease, kidney disease, heart failure.

Pregnancy Risk: Category C. Use diltiazem hydrochloride in pregnant women only if the potential benefit justifies the potential risk to the fetus.

Breastfeeding:  This drug passes into breast milk and may have undesirable effects on a nursing infant. Consult your doctor before breast-feeding.


  • Some products that may interact with this drug include: amiodarone, digoxin, fingolimod.
  • Other medications can affect the removal of diltiazem from your body, which may affect how this medication works. Examples include cimetidine, quinidine, St. John’s wort, azole antifungals such as ketoconazole, macrolide antibiotics such as erythromycin, rifamycins including rifabutin and rifampin.
  • Diltiazem may also affect how your body gets rid of many drugs (such as buspirone, cyclosporine, ivabradine, certain anti-seizure drugs including carbamazepine, certain benzodiazepines including triazolam and midazolam).
  • Cimetidine is a nonprescription drug that is commonly used to treat extra stomach acid. Because cimetidine may interact with diltiazem, ask your pharmacist about other products to treat extra stomach acid.


If overdose is suspected, contact a poison control center or emergency room immediately.


Do not share this medication with others.

Laboratory and/or medical tests (such as kidney/liver function tests, pulse, blood pressure, EKG) may be performed from time to time to monitor your progress or check for side effects. Consult your doctor for more details.

There are different brands and types of this medication available. Many do not have the same effects. Do not change brands or types without consulting your doctor or pharmacist.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.


Store at room temperature at 68-77 degrees F (20-25 degrees C) away from light and moisture. Do not store in the bathroom. Keep all medicines away from children and pets. Different brands of this medication may have different storage needs. Ask your pharmacist about the brand you are using.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.


Available Brands

  • Angiozem [ Littman ]
  • Dilzem [ Pfizer ]

Also marketed as

  • Corvizem [ Vitalink ]
  • Dilatam [ Teva ]
  • Dilcardia [ Danlex ]
  • Diltelan [ OEP Phils ]
  • Dyalac [ Crisdy-Na ]
  • Filazem [ Filadams ]
  • RiteMED Diltiazem [ RiteMED ]
  • Tildiem [ sanofi-aventis ]
  • Vasmulax [ Integrated Pharma ]
  • Zandil [ Therapharma ]
  • Zemtrial [ IAE ]

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