Diltiazem is a commonly used calcium channel blocker primarily used to treat cardiovascular diseases. This medication blocks calcium ions from entering myocardial cells and vascular smooth muscle cells, achieving effects such as vasodilation, slowing heart rate, and lowering blood pressure. Its core indications include hypertension, angina pectoris, and specific types of arrhythmias (such as atrial fibrillation or atrial tachycardia).
Diltiazem increases blood supply to the myocardium and reduces myocardial oxygen consumption by dilating coronary and peripheral blood vessels, making it widely used to stabilize symptoms in patients with angina. Additionally, this medication can regulate the electrophysiological properties of the atria and ventricles, used to control irregular heart rhythms. It is important for physicians to adjust the optimal dosage and administration method based on the patient's age, severity of condition, and other concomitant medications.
The generic name for Diltiazem is Diltiazem Hydrochloride, and it has different brand names in various countries and regions. Common brands in Taiwan include "Cardizem®" and "Tiazac®", while products like "Dilacor XR®" are available in the U.S. market. Some generic medications produced by pharmaceutical companies may be labeled with the generic name or the abbreviation "Diltiazem".
It is important to note that some combination formulations may combine Diltiazem with other antihypertensive medications, but when used alone, it should be based on a physician's prescription. Patients should confirm the active ingredients on the medication label or package insert to avoid misuse.
Diltiazem is classified as a "calcium channel blocker" (CCB) within the "non-dihydropyridine" subtype. Unlike dihydropyridine CCBs (such as amlodipine), Diltiazem has a stronger effect on cardiac electrophysiological properties, thus providing greater advantages in controlling heart rhythm.
Based on its mechanism of action, this medication has both "vasodilatory" and "negative inotropic" effects. This classification feature also determines its unique efficacy in treating angina and arrhythmias, but it is also necessary to be cautious of interactions with other cardiovascular medications.
The main indications for Diltiazem include: hypertension (essential hypertension), stable angina, and tachycardia caused by atrial fibrillation or atrial flutter. In specific situations, physicians may also use it to treat left ventricular outflow tract obstruction due to hypertrophic cardiomyopathy.
Clinically, this medication is often used as an alternative to beta-blockers, especially in patients who cannot tolerate beta-blockers. Additionally, for certain arrhythmia patients who do not respond well to other antiarrhythmic medications, Diltiazem can also serve as a second-line treatment option.
Mild side effects include dizziness, headache, lower limb edema, and fatigue, which usually occur at the beginning of treatment and will alleviate over time. Some patients may experience gastrointestinal discomfort, such as nausea, diarrhea, or bloating. Allergic reactions such as facial flushing or skin itching may occur occasionally.
Serious side effects requiring immediate medical attention:
Contraindications: Severe cardiac conduction block (such as second-degree or third-degree AV block), sick sinus syndrome (without a pacemaker), cardiogenic shock, and individuals allergic to the drug's components should avoid this medication. Patients with severe liver dysfunction should also refrain from using it.
Pregnancy is classified as Category C; women who are pregnant or planning to become pregnant should assess risks with their physician. Use during breastfeeding may lead to bradycardia in infants and should be evaluated cautiously. There have been reports indicating that concurrent use with certain antifungal medications may induce bradycardia, requiring special attention.
Combining Diltiazem with beta-blockers may lead to bradycardia or hypotension, requiring strict monitoring. When used with statin medications (such as atorvastatin), there may be an increased risk of muscle toxicity. Concurrent use with certain antibiotics (such as erythromycin, clarithromycin) or antifungal drugs (such as ketoconazole) may increase the blood concentration of Diltiazem, raising the risk of side effects.
When used with digoxin, Diltiazem may prolong its half-life, increasing the risk of digoxin toxicity. Patients should avoid taking this medication with grapefruit or grapefruit juice, as the components may inhibit liver metabolism, leading to increased drug concentration. When using anticoagulants (such as warfarin), INR values should be monitored, as it may enhance anticoagulant effects.
The initial dose for hypertension treatment is typically 30-60 mg daily, divided into 2-3 doses, with a maximum dose adjustable to 180-360 mg daily. For controlling arrhythmias, more frequent dosing may be required, such as every 6 hours. Extended-release formulations (such as Cardizem CD®) should be swallowed whole and not chewed to maintain stable blood concentrations.
For angina patients, the initial dose may be 30-60 mg orally every 4-6 hours, adjusting the dose based on blood pressure response. Patients with severe heart failure or liver dysfunction should have their doses reduced, typically starting at half the initial dose. It is recommended to take the medication consistently with meals or on an empty stomach, but avoid taking it with high-fat meals to prevent absorption issues.
If a dose is missed within 1-2 hours, it should be taken as soon as possible and the regular dosing schedule resumed. If it is close to the next scheduled dose (such as more than 6 hours), the missed dose should be skipped, and the next dose should be taken at the regular time. Doubling the dose to make up for a missed dose is strictly prohibited.
Long-term missed doses or irregular medication use may lead to poor blood pressure control or recurrent arrhythmias. Patients are advised to use pill organizers or set reminders and to have regular follow-up appointments to assess treatment response.
Diltiazem overdose may cause severe hypotension, bradycardia, or even cardiac arrest. If overdose is suspected, immediate medical attention should be sought, and the medication bottle should be brought for reference. Symptoms may include cold extremities, altered consciousness, and shallow breathing.
Emergency measures include intravenous administration of atropine or isoproterenol to increase heart rate; in severe cases, temporary cardiac pacing may be necessary. Currently, there is no specific antidote, and treatment mainly focuses on supportive care and monitoring of ECG changes.
What should I do if I occasionally forget to take Diltiazem on time?
If a dose of Diltiazem is missed, it should be taken as soon as possible, but if it is close to the next scheduled dose, the missed dose should be skipped, and normal dosing should resume. Do not take a double dose to make up for the missed medication, as this may increase the risk of hypotension or bradycardia.
How can I alleviate dizziness or headache side effects while taking Diltiazem?
Dizziness or headache may be initial side effects that usually resolve as the body adapts to the medication. It is recommended to avoid sudden standing after taking the medication and to rise slowly to reduce the risk of orthostatic hypotension. If symptoms are severe or persistent, contact a doctor immediately for dosage adjustment.
What should I be aware of when using Diltiazem with lipid-lowering medications (such as statins)?
Combining Diltiazem with statin medications may increase the risk of muscle pain or liver function abnormalities. Physicians will regularly monitor liver function and muscle enzymes; patients should avoid adjusting medication doses on their own and report any unexplained muscle soreness or fatigue immediately.
What should I do if arrhythmia symptoms suddenly worsen while undergoing Diltiazem treatment?
If symptoms such as bradycardia (e.g., pulse below 50 beats per minute), worsening dizziness, or syncope occur, it may indicate overdose or cardiac conduction abnormalities. Immediately stop taking the current dose and seek medical attention; do not adjust the medication on your own, and allow a physician to reassess cardiac function and treatment plans.
What preparations should long-term Diltiazem users take before undergoing surgery?
Before planned surgery, inform the anesthesiologist that you are using Diltiazem, as it may interact with anesthetic agents and increase the risk of hypotension. The physician may adjust preoperative medications or monitor cardiac function to ensure surgical safety.
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