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

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

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

1. U.S. Food and Drug Administration (FDA). (2025). Cardizem (Diltiazem) Prescribing Information.
   • Official FDA documentation detailing the drug’s approved uses, dosage, and safety.
2. European Medicines Agency (EMA). (2025). Diltiazem Summary of Product Characteristics.
   • EMA’s comprehensive information on the medication’s indications and precautions in Europe.
3. National Institutes of Health (NIH). (2025). Diltiazem: MedlinePlus Drug Information.
   • NIH resource providing detailed information on the drug’s uses, side effects, and precautions.
4. World Health Organization (WHO). (2025). WHO Model List of Essential Medicines: Diltiazem.
   • WHO’s consideration of Diltiazem for cardiovascular therapy.
5. Journal of the American College of Cardiology. (2024). Diltiazem in Heart Disease Management.
   • Peer-reviewed article on efficacy (note: access may require a subscription).