Diltiazem is a common calcium channel blocker primarily used to treat cardiovascular diseases. This medication inhibits calcium entry into cardiac myocytes and vascular smooth muscle cells, resulting in vasodilation, slowed heart rate, and lowered blood pressure. Its main indications include hypertension, angina pectoris, and certain types of arrhythmias such as atrial fibrillation or atrial flutter.
Diltiazem works by dilating coronary and peripheral arteries, increasing myocardial blood supply, and reducing myocardial oxygen consumption. Therefore, it is widely used to stabilize symptoms in patients with angina. Additionally, the drug can modulate the electrophysiological properties of the atria and ventricles, used to control irregular heart rhythms. It is important to note that physicians will adjust the optimal dosage and administration method based on the patient's age, severity of condition, and concomitant medications.
The generic name of Diltiazem is Diltiazem Hydrochloride. Different countries and regions have various brand names. Common brands in Taiwan include "Cardizem®" and "Tiazac®," while in the United States, products like "Dilacor XR®" are available. Some generic formulations may be labeled with the generic name or abbreviated as "Diltiazem."
It is important to note that some combination formulations may contain Diltiazem along with other antihypertensive agents, but when used alone, it should be prescribed by a healthcare professional. Patients should verify the active ingredients on the medication label or leaflet to avoid misuse.
Diltiazem is classified as a non-dihydropyridine calcium channel blocker within the Calcium Channel Blockers (CCBs) category. Unlike dihydropyridine CCBs (such as amlodipine), Diltiazem has a stronger effect on cardiac electrophysiology, making it more advantageous in controlling heart rhythm.
Based on its mechanism of action, the drug exhibits dual effects of vasodilation and negative inotropic action. This classification also determines its unique efficacy in treating angina and arrhythmias, but it also requires careful consideration of interactions with other cardiovascular drugs.
The primary indications for Diltiazem include: primary hypertension, stable angina pectoris, and tachyarrhythmias caused by atrial fibrillation or atrial flutter. In certain cases, it may also be used to treat left ventricular outflow tract obstruction caused by hypertrophic cardiomyopathy.
Clinically, this medication is often used as an alternative to beta-blockers, especially in patients intolerant to beta-blockers. Additionally, for some arrhythmia patients who do not respond well to other antiarrhythmic drugs, Diltiazem can serve as a second-line treatment option.
Mild side effects include dizziness, headache, lower limb edema, and fatigue, which usually occur early in treatment and tend to resolve over time. Some patients may experience gastrointestinal discomfort such as nausea, diarrhea, or bloating. Occasionally, facial flushing or skin itching may occur as allergic reactions.
Contraindications: Patients with severe cardiac conduction block (such as second- or third-degree atrioventricular block), sick sinus syndrome (without a pacemaker), cardiogenic shock, or known hypersensitivity to the drug should avoid use. Patients with severe hepatic impairment should also avoid this medication.
Pregnancy is classified as Category C; women who are pregnant or planning pregnancy should consult their healthcare provider to evaluate risks. Use during breastfeeding may cause bradycardia in infants and should be carefully considered. Reports have indicated that combining Diltiazem with certain antifungal medications may induce bradycardia, requiring special attention.
Concurrent use of Diltiazem with beta-blockers may lead to excessive bradycardia or hypotension, requiring close monitoring. When combined with statins (such as atorvastatin), there may be an increased risk of myopathy. Using with certain antibiotics (like erythromycin, clarithromycin) or antifungals (like ketoconazole) can elevate Diltiazem blood levels, increasing side effects.
When used with digoxin, Diltiazem may prolong its half-life, increasing the risk of digoxin toxicity. Avoid consuming grapefruit or grapefruit juice during treatment, as components may inhibit hepatic metabolism and raise drug concentrations. When anticoagulants like warfarin are used, INR levels should be monitored as the drug may enhance anticoagulant effects.
For hypertension, the initial dose is usually 30-60 mg daily, divided into 2-3 doses, with a maximum dose of 180-360 mg per day. For arrhythmia control, higher dosing frequency may be required, such as every 6 hours. Extended-release formulations (e.g., Cardizem CD®) should be swallowed whole and not chewed to maintain stable blood concentrations.
Initial doses for angina may be 30-60 mg orally every 4-6 hours, adjusted based on blood pressure response. Patients with severe heart failure or hepatic impairment should start at half the usual dose. Timing of administration should be consistent with meals or fasting, but avoid high-fat meals that may affect absorption.
If a dose is missed within 1-2 hours, take it as soon as possible and resume the regular schedule. If it is close to the next dose (more than 6 hours away), skip the missed dose and continue with the regular schedule the following day. Do not double doses to make up for missed medication.
Long-term missed doses or irregular intake 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 assessments.
Overdose of Diltiazem can cause severe hypotension, bradycardia, or even cardiac arrest. If overdose is suspected, seek immediate medical attention and bring the medication container. Symptoms may include cold extremities, altered consciousness, and shallow or slow breathing.
Emergency treatment includes intravenous atropine or isoproterenol to increase heart rate; in severe cases, temporary pacemaker placement may be necessary. There is no specific antidote; supportive care and continuous ECG monitoring are the main treatments.
If I occasionally forget to take Diltiazem on time, what should I do?
If you miss a dose of Diltiazem, take it as soon as possible. If it is close to the next scheduled dose (more than 6 hours away), skip the missed dose and continue with your regular schedule. Do not take a double dose to compensate for the missed one, as this may increase the risk of hypotension or bradycardia.
How can I reduce dizziness or headache when taking Diltiazem?
Dizziness or headache may be initial side effects that usually improve as your body adjusts to the medication. It is recommended to avoid sudden standing; instead, stand up slowly to reduce orthostatic hypotension. If symptoms are severe or persistent, consult your doctor for dose adjustment.
What should I be aware of when combining Diltiazem with statins or other lipid-lowering drugs?
Combining Diltiazem with statins may increase the risk of muscle pain or liver enzyme abnormalities. Regular monitoring of liver function and muscle enzymes is recommended. Patients should avoid self-adjusting doses and report any unexplained muscle pain or weakness promptly.
If arrhythmia symptoms suddenly worsen during Diltiazem therapy, what should I do?
If you experience bradycardia (heart rate below 50 bpm), worsening dizziness, or syncope, it may indicate overdose or conduction abnormalities. Discontinue the medication immediately and seek medical attention. Do not attempt to adjust the dose yourself; a healthcare professional should reassess your cardiac function and treatment plan.
What precautions should patients on long-term Diltiazem therapy take before surgery?
Patients planning surgery should inform the anesthesiologist about Diltiazem use, 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 safety during the procedure.
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