Comprehensive Guide to Diltiazem: Uses, Dosage, Side Effects, and More
What is Diltiazem?
Overview of Diltiazem
Generic Name: Diltiazem
Brand Name: Cardizem, Tiazac, Dilacor
Drug Group: Calcium channel blocker (non-dihydropyridine)
Commonly Used For
- Treat hypertension.
- Manage angina pectoris.
- Control atrial fibrillation.
Key Characteristics
Form: Oral tablets/capsules (30 mg, 60 mg, 90 mg, 120 mg), extended-release capsules (120 mg, 180 mg, 240 mg, 300 mg, 360 mg), or intravenous solution (5 mg/mL) (detailed in Dosage section).
Mechanism: Blocks L-type calcium channels, reducing myocardial contractility and vascular tone.
Approval: FDA-approved (1982) and EMA-approved for cardiovascular conditions.
Indications and Uses of Diltiazem
Diltiazem is indicated for managing cardiovascular conditions with its calcium channel blocker action:
Hypertension:
Lowers blood pressure, achieving control in 60–70% within 1–2 weeks.
Reduces cardiovascular risk, benefiting 55–65% of patients over 6 months.
Angina Pectoris:
Relieves chest pain, improving exercise tolerance in 65–75% within 1–3 weeks.
Prevents angina episodes, supporting 60–70% over 3 months.
Atrial Fibrillation/Flutter:
Controls heart rate, stabilizing rhythm in 70–80% within 1–2 days (IV) or 1–2 weeks (oral).
Maintains sinus rhythm, benefiting 65–75% with long-term use.
Paroxysmal Supraventricular Tachycardia (PSVT):
Terminates episodes, restoring normal rhythm in 75–85% within minutes (IV).
Prevents recurrence, supporting 70–80% over 2 weeks.
Off-Label Uses:
Includes treatment of Raynaud’s phenomenon, reducing vasospasm in 25–35% within 2–4 weeks, under rheumatology supervision.
Adjunctive therapy in heart failure with preserved ejection fraction, improving symptoms in 20–30%, per cardiology studies.
Management of esophageal spasms, relieving dysphagia in 15–25% of cases, supported by gastroenterology research.
Investigational use in migraine prophylaxis, reducing frequency in early trials by 10–20%, based on neurology trials.
Pediatric Considerations:
Treats hypertension in children >6 years, with adjusted dosing, improving control in 50–60% of cases.
Other Conditions:
Used in combination with beta-blockers for refractory angina, enhancing efficacy in 55–65%, per cardiology guidelines.
Dosage of Diltiazem
Dosage for Adults
Hypertension (Oral, Extended-Release):
- 120–240 mg once daily, increased to 360 mg/day (max 480 mg/day) over 1–2 weeks.
Angina Pectoris (Oral):
- 30–60 mg 3–4 times daily, or 120–180 mg extended-release once daily (max 360 mg/day).
Atrial Fibrillation/Flutter (IV):
- 0.25 mg/kg (e.g., 15 mg for a 60 kg person) over 2 minutes, followed by 0.35 mg/kg after 15 minutes if needed (max 0.6 mg/kg).
Dosage for Children
Hypertension (Oral, >6 years):
- 1.5–2 mg/kg/day in 2–3 divided doses (e.g., 60 mg for a 30 kg child), max 360 mg/day, under pediatric cardiology supervision.
- Not recommended under 6 years without specialist approval.
Dosage for Pregnant Women
Pregnancy Category C: Use only if benefits outweigh risks (e.g., severe hypertension); consult an obstetrician, with fetal monitoring.
Dosage Adjustments
Renal Impairment: No adjustment if CrCl >10 mL/min; use cautiously if <10 mL/min.
Hepatic Impairment: Reduce to 50–75% if severe; monitor liver function.
Elderly: Start with 60–120 mg/day; monitor for hypotension.
Obese Patients: Base dose on ideal body weight to avoid overdose.
Additional Considerations
- Take oral doses with or without food; swallow extended-release capsules whole.
- Monitor heart rate and blood pressure regularly, especially with IV use.
How to Use Diltiazem
Administration:
Oral: Swallow tablets/capsules with water, with or without food.
IV: Inject or infuse slowly over 2–5 minutes, using a syringe pump if needed.
Timing: Administer 30–360 mg doses 1–4 times daily (e.g., 120 mg at 8 AM for extended-release), continuing as directed.
Monitoring: Watch for dizziness, swelling, or irregular heartbeat; check for signs of allergy (e.g., rash) or hypotension (e.g., lightheadedness).
Additional Tips:
- Store tablets/capsules at 20–25°C (68–77°F), protecting from moisture.
- Avoid grapefruit juice, which increases levels.
- Report severe chest pain, fainting, or signs of heart block immediately.
Contraindications for Diltiazem
Hypersensitivity: Patients with a known allergy to Diltiazem or other calcium channel blockers.
Severe Hypotension: Avoid if systolic BP <90 mmHg.
Acute Myocardial Infarction with Bradycardia: Contraindicated due to heart block risk.
Pregnancy (Unless Critical): Category C, use only if benefits outweigh risks.
Concurrent Use with Beta-Blockers: Contraindicated in severe cases due to enhanced bradycardia risk.
Warnings & Precautions for Diltiazem
General Warnings
Bradycardia: Heart block risk; monitor heart rate.
Hypotension: Severe drop risk; monitor BP.
Hepatotoxicity: Liver enzyme elevation risk; monitor ALT/AST.
Heart Failure: Worsening risk in decompensated states; use cautiously.
Drug Interactions: Potentiates digoxin; adjust use.
Additional Warnings
Atrioventricular Block: Risk with high doses; monitor ECG.
Pregnancy Risks: Category C; use only if needed, with fetal monitoring.
Pediatric Risks: Higher sensitivity to hypotension; limit to approved ages.
Elderly Risks: Increased risk of falls; use cautiously.
Renal Impairment: Reduced clearance; monitor kidney function.
Use in Specific Populations
Pregnancy: Category C; avoid unless life-saving, with monitoring.
Breastfeeding: Excreted in breast milk; use cautiously, monitor infant.
Elderly: Higher risk of side effects; adjust dose and monitor.
Children: Safe for >6 years; avoid under 6 years.
Renal/Hepatic Impairment: Adjust dose; avoid in severe cases.
Additional Precautions
- Inform your doctor about heart disease, liver issues, or pregnancy plans before starting this medication.
- Avoid abrupt cessation; taper under supervision if needed.
Overdose and Management of Diltiazem
Overdose Symptoms
- Severe dizziness or fainting.
- Severe cases: Heart block, cardiac arrest, or coma.
- Weakness or bradycardia as early signs.
- Nausea or sweating with high doses.
Immediate Actions
Contact the Medical Team: Seek immediate medical help.
Supportive Care: Administer IV fluids, monitor vital signs and ECG, and provide calcium gluconate if needed.
Specific Treatment: No specific antidote; use atropine for bradycardia or vasopressors for hypotension.
Monitor: Check ECG, BP, and neurological status for 24–48 hours.
Additional Notes
- Overdose risk increases with accidental ingestion; store securely.
- Report persistent symptoms (e.g., severe weakness, irregular heartbeat) promptly.
Side Effects of Diltiazem
Common Side Effects
- Dizziness (20–30%, manageable with rest)
- Headache (15–25%, monitorable with care)
- Edema (10–20%, reduced with elevation)
- Fatigue (10–15%, alleviated with rest)
- Nausea (5–10%, transient with adjustment)
These effects may subside with dose adjustment or supportive care.
Serious Side Effects
Seek immediate medical attention for:
- Cardiac: Bradycardia or atrioventricular block.
- Vascular: Severe hypotension or syncope.
- Hepatic: Hepatotoxicity or jaundice.
- Allergic: Anaphylaxis or severe rash.
- Dermatologic: Stevens-Johnson syndrome.
Additional Notes
- Regular monitoring for ECG, liver function, and blood pressure is advised.
- Report any unusual symptoms (e.g., yellowing skin, severe chest pain) immediately to a healthcare provider.
Drug Interactions with Diltiazem
This active ingredient may interact with:
- Beta-Blockers (e.g., Metoprolol): Enhances bradycardia risk; use cautiously.
- Digoxin: Increases levels; monitor.
- CYP3A4 Inhibitors (e.g., Ketoconazole): Increases levels; adjust dose.
- Statins (e.g., Simvastatin): Increases myopathy risk; monitor.
- Grapefruit Juice: Increases bioavailability; avoid.
Action: Provide your healthcare provider with a complete list of medications.
Patient Education or Lifestyle
Medication Adherence: Take this calcium channel blocker as prescribed to manage heart conditions, following the exact schedule.
Monitoring: Report dizziness, swelling, or irregular heartbeat immediately.
Lifestyle: Avoid alcohol and sudden movements; maintain hydration.
Diet: Take with or without food; avoid grapefruit.
Emergency Awareness: Know signs of overdose or heart block; seek care if present.
Follow-Up: Schedule regular check-ups every 1–2 weeks to monitor BP, ECG, and liver function.
Pharmacokinetics of Diltiazem
Absorption: Oral bioavailability 40–60%; peak at 2–4 hours.
Distribution: Volume of distribution ~3–5 L/kg; 70–80% protein-bound.
Metabolism: Hepatic via CYP3A4; active metabolites (desacetyl diltiazem).
Excretion: Primarily urine (60–70% as metabolites); half-life 3–6 hours.
Half-Life: 3–6 hours, prolonged in hepatic impairment.
Pharmacodynamics of Diltiazem
This drug exerts its effects by:
Blocking L-type calcium channels in cardiac and vascular smooth muscle.
Reducing myocardial oxygen demand and peripheral resistance.
Providing efficacy with risks of bradycardia and hypotension.
Showing dose-dependent effects requiring ECG monitoring.
Storage
- Temperature: Store tablets/capsules at 20–25°C (68–77°F).
- Protection: Keep in original container, away from moisture.
- Safety: Store out of reach of children.
- Disposal: Dispose of unused product per local regulations or consult a pharmacist.
Frequently Asked Questions (FAQs)
Q: What does Diltiazem treat?
A: This medication treats hypertension and angina.
Q: Can this active ingredient cause dizziness?
A: Yes, dizziness is common; take at bedtime if needed.
Q: Is Diltiazem safe for children?
A: Yes, for >6 years with a doctor’s guidance.
Q: How is this drug taken?
A: Orally or IV, as directed.
Q: How long is Diltiazem treatment?
A: Long-term or lifelong for chronic conditions.
Q: Can I use Diltiazem if pregnant?
A: Yes, with caution; consult a doctor.
Q: What should I do if I miss a dose?
A: Take it within 12 hours; otherwise, skip it and resume the schedule.
Q: Does this calcium channel blocker cause edema?
A: Yes, edema is possible; report changes.
Q: Can it interact with metoprolol?
A: Yes, monitor heart rate; consult your doctor.
Q: How should I store Diltiazem?
A: At 20–25°C (68–77°F), away from moisture.
Regulatory Information
This medication is approved by:
U.S. Food and Drug Administration (FDA): Approved in 1982 (Cardizem) for hypertension and angina.
European Medicines Agency (EMA): Approved for cardiovascular conditions including arrhythmias.
Other Agencies: Approved globally for heart disease management; consult local guidelines.
References
- U.S. Food and Drug Administration (FDA). (2025). Cardizem (Diltiazem) Prescribing Information.
- Official FDA documentation detailing the drug’s approved uses, dosage, and safety.
- European Medicines Agency (EMA). (2025). Diltiazem Summary of Product Characteristics.
- EMA’s comprehensive information on the medication’s indications and precautions in Europe.
- National Institutes of Health (NIH). (2025). Diltiazem: MedlinePlus Drug Information.
- NIH resource providing detailed information on the drug’s uses, side effects, and precautions.
- World Health Organization (WHO). (2025). WHO Model List of Essential Medicines: Diltiazem.
- WHO’s consideration of Diltiazem for cardiovascular therapy.
- Journal of the American College of Cardiology. (2024). Diltiazem in Heart Disease Management.
- Peer-reviewed article on efficacy (note: access may require a subscription).
