Diltiazem (Cardizem): Uses, Warnings, and Key Facts
Quick summary: Diltiazem is a calcium channel blocker used for high blood pressure and angina. It is available in different oral forms, and the exact product, dose, and instructions can vary by brand and...
This content is for educational purposes only and does not replace medical advice, diagnosis or treatment from a qualified healthcare professional.
Quick summary: Diltiazem is a calcium channel blocker used for high blood pressure and angina. It is available in different oral forms, and the exact product, dose, and instructions can vary by brand and formulation.
This article summarizes the information in the original content and highlights the main safety points, interactions, and administration notes to verify with the official leaflet or a healthcare professional.
Medical disclaimer: This page is for general information only. It does not replace the advice of a doctor, pharmacist, or the official product leaflet. Do not use this information to diagnose a condition, and do not start, stop, or change any medicine without professional guidance.
What is diltiazem?
Diltiazem is a medicine used to treat high blood pressure and angina. The original content lists the active ingredient forms as diltiazem hydrochloride, diltiazem malate, and diltiazem maleate.
In the United States, brand names mentioned in the source include Cardizem, Cartia XT, Dilt-XR, and Cardizem CD.
How diltiazem works
Diltiazem limits calcium entry through slow calcium channels in vascular smooth muscle and heart muscle. This reduces intracellular calcium and helps explain its effects on blood vessels and the heart.
What diltiazem is used for
The original content identifies two main uses:
- Angina treatment and prevention
- High blood pressure
Different oral formulations may be used in different ways, so the exact instructions depend on the product prescribed.
Dosage information from the original content
The source describes oral use in adults and notes that there are immediate-release and prolonged-release preparations. It also states that switching between formulations is not recommended unless specifically advised by the prescribing physician.
It is also noted that treatment is generally started with the lowest possible dose and adjusted according to response and tolerability.
| Use | Information in the source |
|---|---|
| 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 | 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. Max. dose: 360 mg/day. |
Important: These figures come from the original content and may not apply to every product or patient. Always check the exact label for the prescribed formulation.
How it is taken
Oral administration
- Immediate-release tablets: take before main meals.
- Prolonged-release tablets: take with or without food, at the same time each day, and swallow whole with water.
- Prolonged-release capsules: take at the same time each day, with or without food, and swallow whole with a little water.
The source emphasizes that oral formulations are not interchangeable unless a clinician specifically recommends the change.
When diltiazem should not be used
The original content lists the following contraindications:
- Hypersensitivity to diltiazem
- Sinus node disease and second- or third-degree atrioventricular block, unless a functioning ventricular pacemaker is present
- Severe bradycardia
- Left ventricular insufficiency with pulmonary congestion
- Hypotension
- Complicated acute myocardial infarction
- Shock
- Congestive heart failure with pulmonary edema or left ventricular ejection fraction below 40%
- Concomitant use with dantrolene infusion
- Atrial fibrillation or flutter with Wolff-Parkinson-White syndrome
- Pregnancy and lactation
- Combination with ivabradine
- Women of childbearing age who do not use a suitable contraceptive method
Warnings and precautions
The source highlights extra caution in the following situations:
- Liver failure
- Kidney failure
- Older adults
- During anesthesia
- Risk of intestinal obstruction
- Diabetes mellitus, due to possible increases in blood glucose
- Left ventricular insufficiency
- Bradycardia
- First-degree AV block
- Chronic heart failure
- Need for liver and kidney function monitoring
- Need for regular heart rhythm monitoring
- Risk of symptomatic hypotension
- Depression
- Use in children is not recommended
Liver and kidney impairment
Liver failure
The source states that diltiazem is mainly metabolized in the liver. If liver function is impaired, plasma levels may increase, so dose adjustment and close monitoring are advised.
Renal insufficiency
The source also advises caution in renal insufficiency because active metabolites may accumulate. Initial dose adjustment and periodic monitoring are recommended in prolonged treatment.
Drug interactions
The original content lists several interactions that should be checked carefully with a pharmacist or prescriber:
- Contraindicated: IV dantrolene, ivabradine
- May enhance blood pressure lowering: alpha antagonists, nitrate derivatives
- May cause rhythm or conduction problems / heart failure risk: beta-blockers
- May increase bradycardia risk: amiodarone, digoxin
- Additive effect: antiarrhythmics
- May increase levels of: cyclosporine, carbamazepine, theophylline
- May increase diltiazem levels: cimetidine, ranitidine
- May decrease diltiazem levels: rifampicin
- May increase neurotoxicity: lithium
- May increase oral concentrations of: lovastatin, simvastatin, triazolam, midazolam, tacrolimus, buspirone, prednisone
- Monitor when starting: methylprednisolone
- Myopathy/rhabdomyolysis risk: statins metabolized by CYP3A4
Pregnancy and breastfeeding
The source states that diltiazem is contraindicated in pregnancy and that it is teratogenic in certain animal species.
For breastfeeding, the source says diltiazem is excreted in low concentrations in breast milk and that breastfeeding should be avoided during treatment.
Driving and using machines
No studies were found in the original content on driving or machine use. However, because diltiazem may lower blood pressure and cause dizziness or fainting at the start of treatment, caution is advised with tasks that require attention until the response is known.
Possible adverse reactions
The source lists the following side effects and adverse reactions:
- Headache
- Dizziness
- Atrioventricular block
- Palpitations
- Flushing
- Constipation
- Dyspepsia
- Gastric pain
- Nausea
- Erythema
- Rash
- Lower-limb edema
- Malaise
FAQ
▸ What is diltiazem mainly used for?
Diltiazem is used for high blood pressure and angina, according to the original content.
▸ Are all diltiazem products taken the same way?
No. The source distinguishes between immediate-release and prolonged-release forms, and it says they should not be substituted for one another unless a clinician specifically recommends it.
▸ Can diltiazem interact with other heart medicines?
Yes. The original content lists interactions with beta-blockers, amiodarone, digoxin, ivabradine, and other medicines. A pharmacist or prescriber should review the full medication list.
▸ What side effects are mentioned in the source?
The source mentions headache, dizziness, flushing, constipation, nausea, palpitations, edema, rash, and atrioventricular block among others.
▸ Should pregnancy or breastfeeding be checked before use?
Yes. The original content states that diltiazem is contraindicated in pregnancy and that breastfeeding should be avoided during treatment.
▸ Where can I verify the official information?
Check the FDA medication guide and the official leaflet for the exact product and formulation prescribed.
Safety reminder: If you have chest pain, fainting, severe dizziness, a very slow heartbeat, breathing problems, or signs of an allergic reaction, seek urgent medical help. Always confirm the exact diltiazem product, strength, and instructions on the package leaflet or with a healthcare professional.
Sources and official references
The original content cites FDA-related and scientific identifier resources. Useful places to verify official information include the FDA medication guide and the product-specific label.
Medical disclaimer
This content is for educational purposes only. It should not be used as a substitute for professional medical advice, diagnosis or treatment. Always ask a doctor, pharmacist or qualified healthcare professional before starting, stopping or changing any medicine.
Sources and verification
The following sources or official references are listed to support verification of the medicine information discussed in this article.
Medicine information can change and may vary depending on country, product formulation, patient history and professional guidance. Always check official medicine information and ask a healthcare professional for personal medical questions.