1. Introduction
Isosorbide dinitrate is a nitrate vasodilator used to prevent and manage angina pectoris and heart failure. It works by relaxing blood vessels, reducing myocardial oxygen demand, and improving blood flow to the heart.
2. Indications
- Approved Indications:
- Angina pectoris (chronic and stable angina).
- Acute and chronic heart failure (as part of combination therapy, e.g., with hydralazine).
- Acute angina episodes (sublingual form).
- Off-Label Uses:
- Pulmonary hypertension (in specific cases).
3. Dosage
- Chronic Angina Prevention:
- Immediate-release: 10–40 mg orally 2–3 times daily, ensuring a nitrate-free interval of at least 14 hours to prevent tolerance.
- Extended-release: 40–80 mg once daily in the morning or as directed.
- Acute Angina Episodes:
- Sublingual tablets: 2.5–10 mg under the tongue as needed. May repeat every 5–10 minutes, up to 3 doses in 15 minutes.
- Heart Failure:
- 20–30 mg 2–3 times daily, titrated based on clinical response.
- Elderly:
- Use the standard adult dose but monitor closely for hypotension or dizziness.
4. Administration
- Oral Tablets: Take with water. Immediate-release forms should be taken at regular intervals, ensuring a nitrate-free period.
- Sublingual Tablets: Place under the tongue and let dissolve completely without swallowing.
- Extended-Release Tablets: Swallow whole; do not crush or chew.
5. Forms Available
- Sublingual tablets: 2.5 mg, 5 mg, 10 mg.
- Oral tablets (immediate-release): 5 mg, 10 mg, 20 mg, 40 mg.
- Extended-release tablets: 40 mg, 60 mg.
6. Side Effects
6.1. Common Side Effects
- Headache (often severe initially).
- Dizziness or light-headedness.
- Flushing.
6.2. Less Common Side Effects
- Nausea.
- Fatigue.
6.3. Rare but Serious Side Effects
- Severe hypotension.
- Syncope (fainting).
- Paradoxical angina (worsening chest pain).
7. Warnings
- Tolerance: Continuous use without a nitrate-free interval leads to reduced efficacy.
- Hypotension: Increased risk in volume-depleted or hypotensive patients.
- Interaction with Phosphodiesterase Inhibitors: Concomitant use with sildenafil, tadalafil, or vardenafil may result in life-threatening hypotension.
8. Precautions
- Use cautiously in patients with:
- Severe hypotension or shock.
- Hypertrophic obstructive cardiomyopathy (may worsen symptoms).
- Cerebrovascular disease (increased risk of syncope).
9. Interactions
- Drug-Drug Interactions:
- Phosphodiesterase inhibitors (e.g., sildenafil): Severe hypotension risk.
- Alcohol: Exacerbates dizziness and hypotension.
- Antihypertensives: Additive blood pressure-lowering effects.
- Drug-Food Interactions:
- No significant interactions, but avoid alcohol.
10. Monitoring Parameters
- Frequency and severity of angina episodes.
- Blood pressure (to detect hypotension).
- Signs of adverse effects (e.g., headache, dizziness).
11. Use in Children
- Not recommended for use in children, as safety and efficacy have not been established.
12. Use in Pregnancy
- Category C: Use only if the benefits outweigh risks. Consult a healthcare provider for use during pregnancy.
13. Use in Elderly
- Safe for use but monitor for increased sensitivity to hypotension and dizziness.
14. Use in Kidney Disease
- No dose adjustment is typically required, as isosorbide dinitrate is metabolised by the liver.
15. Use in Liver Disease
- Use cautiously in severe liver impairment due to altered metabolism of the drug.
16. Patient Counselling Points
- Take isosorbide dinitrate as prescribed, ensuring a nitrate-free interval to prevent tolerance.
- Headaches are common initially and usually improve with continued use. Use paracetamol for headache relief if needed.
- Avoid alcohol, as it may increase dizziness and flushing.
- For acute angina episodes, use sublingual tablets as directed and seek medical help if symptoms persist after 3 doses in 15 minutes.
- Report severe dizziness, fainting, or worsening chest pain to your doctor immediately.
17. Table of Brand Names, Manufacturers, and Prices
Brand Name | Manufacturer | Price (USD) |
---|---|---|
Isordil (sublingual) | Pfizer | $15–25 (30 tablets, 10 mg) |
Sorbitrate | Abbott Laboratories | $10–20 (30 tablets, 10 mg) |
Generic Isosorbide Dinitrate | Various manufacturers | $5–15 (30 tablets, 10 mg) |
18. FAQs (15 Questions)
- What is isosorbide dinitrate used for?
It is used to prevent angina, treat heart failure, and manage acute angina episodes. - How does isosorbide dinitrate work?
It relaxes blood vessels, reducing the heart’s workload and improving oxygen delivery to the heart. - How long does isosorbide dinitrate take to work?
Sublingual tablets work within 2–5 minutes, while oral forms may take 30–60 minutes. - Can isosorbide dinitrate cause headaches?
Yes, headaches are a common side effect, especially during initiation of therapy. - What is the difference between isosorbide dinitrate and isosorbide mononitrate?
Isosorbide dinitrate is a prodrug converted into the active form (mononitrate), while isosorbide mononitrate is directly active and longer-acting. - How should isosorbide dinitrate be taken?
Take as prescribed, ensuring a nitrate-free interval to prevent tolerance. - What should I do if I miss a dose?
Take it as soon as you remember, but skip it if it is close to your next dose. Do not double up. - Can I drink alcohol while taking isosorbide dinitrate?
Avoid alcohol, as it may worsen side effects like dizziness and hypotension. - Is isosorbide dinitrate safe during pregnancy?
Use only if necessary, under the guidance of a healthcare provider. - Can isosorbide dinitrate cause low blood pressure?
Yes, hypotension is a common side effect, especially in volume-depleted patients. - Can I use isosorbide dinitrate for an acute angina attack?
Yes, sublingual tablets are effective for immediate relief of acute angina episodes. - Does isosorbide dinitrate interact with other medications?
Yes, it interacts with phosphodiesterase inhibitors, antihypertensives, and alcohol. - How should I store isosorbide dinitrate?
Store at room temperature, away from moisture and heat. - Can isosorbide dinitrate cause dizziness?
Yes, dizziness is a common side effect, particularly when starting treatment. - What should I do if chest pain persists after using isosorbide dinitrate?
Seek immediate medical attention if symptoms persist after 3 doses within 15 minutes.