DILTIAZEM (CARDIZEM): What is used for?

What is Diltiazem?

Diltiazem is a drug used to treat high blood pressure and angina. The product ingredienst are: Diltiazem hydrochloride (hcl), Diltiazem malate, Diltiazem maleate.

The brand names of Diltiazem in the United States are: Cardizem, Cartia XT, Dilt-XR, Cardizem CD.

Mechanism of action (MOA) of Diltiazem

Diltiazem selectively limits calcium entry through the slow calcium channels of vascular smooth muscle and myocardial muscle fibers in a voltage-dependent manner. By means of this mechanism, diltiazem reduces the concentration of intracellular calcium.

Therapeutic indications, benefits and dosage of Diltiazem



There are two types of preparations for the oral route: quick release (distribute the dose in 2-3 doses) and prolonged release (allows a single daily dose). Due to the differences in bioavailability and speed of absorption between the different oral forms, the substitution of one for the other is not recommended unless expressly recommended by the prescribing physician.
It is advisable to start treatment with the lowest possible dose and adjust according to response and tolerability.

Recommended dose:

Treatment and prevention of angina: start: 60 mg/12 h, maintenance: 180-360 mg/day in one or more doses depending on the preparation. In unstable angina the maximum dose is 480 mg/day.

High blood pressure (HBP): start 120-240 mg/day, maintenance: 180-360 mg/day in one or more doses depending on the preparation. The maximum antihypertensive effect is normally observed after 14 days of treatment. Max. dose: 360 mg/day.

Method of administration of Diltiazem

Oral use:

  1. Immediate-release tablets: to be administered before main meals.
  2. Prolonged-release tablets: administer with or without food. Always take at the same time. Take whole,         without chewing and with a glass of water.
  3. Prolonged-release capsules: administer at the same time at any time of day, with or without food, take         whole with a little water.

Contraindications of Diltiazem

  • Hypersensitivity to diltiazem.
  • Sinus node disease and second or third degree atrioventricular block, except in the presence of a functioning ventricular pacemaker.
  • Severe bradycardia (< or = equal to 40 beats per minute).
  • Left ventricular insufficiency with pulmonary congestion.
  • Hypotension (systolic blood pressure < 90 mmHg).
  • Complicated AMI (bradycardia, severe hypotension, ventricular insufficiency).
  • Shock.
  • Congestive heart failure with pulmonary edema or left ventricular ejection fraction. (LVEF) < 40%.
  • Concomitant with dantrolene (infusion).
  • Atrial fibrillation or flutter with s. Wolff-Parkinson-White.
  • Pregnancy and lactation.
  • Combination with ivabradine.
  • Women of childbearing age who do not use a suitable contraceptive method.

Warnings and precautions with Diltiazem

  • Liver failure.
  • Kidney failure.
  • Elderly.
  • Anesthesia.
  • Patients at risk of developing intestinal obstruction, diabetes mellitus (due to possible increase in blood glucose), monitoring in case of: left ventricular insufficiency, bradycardia (risk of aggravation) or first-degree AV block (risk of aggravation).
  • Chronic heart failure (CHF).
  • Monitoring of liver and kidney function.
  • Regular control of heart rhythm (should not fall below 50 beats/min).Risk of symptomatic hypotension, depression.
  • Not recommended for children.

Liver failure

Caution. Since diltiazem is metabolized mainly at hepatic level, in case of alteration of hepatic function there could be an increase in the plasma levels of diltiazem, so the dosage must be adjusted according to the hepatic functional level.
Strict monitoring at the beginning of treatment, periodic monitoring of parameters in prolonged treatments.

Renal insufficiency

Caution. Since diltiazem is mostly eliminated by the renal route, an accumulation of active metabolites could occur, for this reason, the initial dose adjustment should be made with caution.
Strict monitoring at the beginning of treatment, periodic monitoring of parameters in prolonged treatment.

Interactions with Diltiazem

  • Contraindicated association with: administration IV with dantrolene, ivabradine.
  • Enhancement of the hypotensive effect with: alpha antagonists, nitrate derivatives.
  • Rhythm disorders, conduction alterations and heart failure with: ß-blockers.
  • Increased risk of bradycardia with: amiodarone, digoxin.
  • Additive effect with: antiarrhythmics.
  • Increases levels of: cyclosporine, carbamazepine, theophylline.
  • Plasma levels increased by: cimetidine, ranitidine.
  • Plasma levels decreased by: rifampicin.
  • Increased neurotoxicity with: lithium.
  • May increase (orally) plasma concentrations of: lovastatin, simvastatin, triazolam, midazolam, tacrolimus, buspirone, prednisone.
  • Monitor when starting treatment with methylprednisolone.
  • Risk of myopathy and rhabdomyolysis with statins metabolized by CYP3A4.

Pregnancy and Diltiazem

Contraindicated, it is teratogenic in certain animal species.


It is excreted at low concentrations by breast milk. Breastfeeding should be avoided during treatment.

Effects on driving ability

No studies have been conducted on the effects on the ability to drive vehicles or use machines. However, since a drop in blood pressure may occur at the start of treatment and may be accompanied by dizziness and even fainting in some cases, it is advisable not to perform tasks requiring special attention until the response is satisfactory.

Adverse reactions and side effects of Diltiazem

Headache, dizziness; atrioventricular block (may be first, second, or third degree; blockage of the branch of the beam may occur), palpitations; flushing; constipation, dyspepsia, gastric pain, nausea; erythema, rash; edema of the lower limbs, malaise.


Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).

In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.


PubChem CID: 39186
NCI Thesaurus: C61725

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