API: Diltiazem

What Is Diltiazem and How Does It Work?

Diltiazem is a nondihydropyridine, benzothiazepine-derived calcium channel blocker that is primarily used to treat hypertension, angina, and arrhythmia.  By blocking the influx of extracellular calcium ions into myocardial and vascular smooth muscle cells, the drug causes vasodilation of the coronary and peripheral systemic arteries. This lowers blood pressure by reducing peripheral resistance and allowing blood to flow more easily. It also decreases heart contractility by slowing conduction through the atrioventricular node and the sinoatrial node.1

Approved Indications2:

  • Hypertension: Diltiazem effectively treats hypertension by lowering blood pressure.
  • Chronic Stable Angina Pectoris: Because it works to improve blood flow through the coronary arteries, Diltiazem can be used for long-term management of chronic stable angina pectoris.
  • Atrial Fibrillation/Flutter: Diltiazem can help normalize heart rhythms by decreasing heart contractility.
  • Paroxysmal Supraventricular Tachycardia: Tachycardia is characterized by fast heart rate, and diltiazem works to lower heart rate.
  • Migraine Prophylaxis: Diltiazem is sometimes used off-label for migraine prevention.3

Side Effects and Drug Interactions:

Common side effects of diltiazem include4:

  • Headache
  • Feeling dizzy or lightheaded
  • Low heart rate
  • Weakness
  • Vomiting
  • Constipation or Diarrhea
  • Nasal congestion
  • Cough

Patients should contact a physician immediately if they experience the following serious side effects:

  • Swelling of the face, lips, tongue, eyes, hands, arms, feet, lower legs, or ankles
  • Fainting
  • Difficulty breathing or swallowing
  • Jaundice
  • Rash
  • Bleeding or bruising easily
  • Extreme fatigue
  • Loss of appetite
  • Upper right stomach pain
  • Increased chest pain

Patients who have a history of congestive heart failure, sick sinus syndrome, atrioventricular block, low heart rate, low blood pressure, liver disease, or kidney disease should talk to a doctor before taking diltiazem. Patients who are pregnant or breastfeeding should only take diltiazem if it is absolutely necessary.5

Diltiazem is both an inhibitor and a substrate of the enzyme CYP3A4, so taking it in conjunction with other drugs that act on the enzyme could alter its efficacy or side effects. These drugs include benzodiazepines, beta blockers, carbamazepine, cimetidine, HIV protease inhibitors, tricyclic antidepressants, quinidine, rifampin, and certain statins.6 Patients are also advised against taking diltiazem alongside grapefruit juice, which contains bergamottin, another inhibitor of CYP3A4.7

Latest News and Research

Recent research probes the relationship between diltiazem and diabetes. One study found that type II diabetes patients who took blood pressure medications, including diltiazem, were less likely to die prematurely or suffer from a heart attack or stroke, even if they had not been specifically diagnosed with hypertension.8 Diltiazem may also provide effective treatment for diabetes mellitus.9 Investigations into how the drug works to treat these conditions are ongoing.

Scientists are also exploring other alternative uses for diltiazem. Recent research indicates that diltiazem can decrease cocaine cravings in rats, most likely because of the effects of calcium channel blockers on dopaminergic and glutaminergic signaling, and some scientists hope to use the drug to treat cocaine addiction in the future.10 Studies also show that diltiazem can be taken orally or applied topically to heal chronic anal fissures.11 Diltiazem may also facilitate kidney stone passage.12

Buying Guide

Many compound pharmacists elect Verapamil and Nifedipine, which are calcium channel blockers that treat many of the same conditions as diltiazem but interact with fewer medications. Please find more information about our Bulk APIs here.

Show 12 footnotes

  1. “Diltiazem,” 2016, https://pubchem.ncbi.nlm.nih.gov/compound/39186
  2. “Dosing & Uses,” 2016, http://reference.medscape.com/drug/cardizem-cd-diltiazem-342374#0
  3. “Medications for Migraine Prophylaxis,” January 2006, http://www.aafp.org/afp/2006/0101/p72.html
  4. “What is Diltiazem (Cardizem)?” October 27, 2014, http://www.everydayhealth.com/drugs/diltiazem
  5. “Diltiazem,” 2016, http://www.webmd.com/drugs/2/drug-3783-276/diltiazem-oral/diltiazem-tablet—oral/details#precautions
  6. “Drug Interactions,” January 5, 2011, http://www.rxlist.com/cardizem-la-drug/side-effects-interactions.htm
  7. “Inactivation of cytochrome P450 3A4 by bergamottin, a component of grapefruit juice,” April 1998, https://www.ncbi.nlm.nih.gov/pubmed/9548795
  8. “Blood Pressure Meds Lower Heart, Stroke Risks in Diabetics: Analysis,” February 10, 2015, http://www.drugs.com/news/blood-pressure-meds-lower-heart-stroke-risks-diabetics-analysis-55580.html
  9. “Dihydropyridine calcium-channel blockers for the treatment of hypertensive diabetic patients,” 2000, https://eurheartj.oxfordjournals.org/content/ehj/21/1/2.full.pdf
  10. “Common Heart Drug May Reduce Cocaine Cravings,” February 28, 2008, https://www.sciencedaily.com/releases/2008/02/080227155016.htm
  11. “A randomized trial of oral vs. topical diltiazem for chronic anal fissures,” August 2001, http://www.ncbi.nlm.nih.gov/pubmed/11535842
  12. “Adjunctive Therapy to Promote Stone Passage,” Spring 2005, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1477562/