Isosorbide Dinitrate 20mg Tablets
It is used to prevent chest pain (angina pectoris) in people with heart disease.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antianginal, Vasodilator
Pharmacologic Class
Organic Nitrate
Pregnancy Category
C
FDA Approved
Jan 1951
DEA Schedule
Not Controlled
Overview
What is this medicine?
Isosorbide dinitrate is a medication used to prevent chest pain (angina) caused by heart disease. It works by relaxing blood vessels, which helps more blood and oxygen reach your heart, and reduces the workload on your heart.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, take it exactly as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. If you need to stop taking this medication, do not stop suddenly without first consulting your doctor, as this may increase your risk of side effects. Instead, your doctor will advise you on how to gradually taper off the medication.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature, away from direct light and moisture. Keep the container in a dry place, such as a closet or drawer, and avoid storing it in the bathroom. Make sure to keep the lid tightly closed. It is also essential to keep all medications in a secure location, out of the reach of children and pets, to prevent accidental ingestion.
What to Do If You Miss a Dose
If you forget to take a dose, take it as soon as you remember. However, if it is close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To get the most benefit from your medication, take it exactly as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. If you need to stop taking this medication, do not stop suddenly without first consulting your doctor, as this may increase your risk of side effects. Instead, your doctor will advise you on how to gradually taper off the medication.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature, away from direct light and moisture. Keep the container in a dry place, such as a closet or drawer, and avoid storing it in the bathroom. Make sure to keep the lid tightly closed. It is also essential to keep all medications in a secure location, out of the reach of children and pets, to prevent accidental ingestion.
What to Do If You Miss a Dose
If you forget to take a dose, take it as soon as you remember. However, if it is close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take this medication exactly as prescribed, usually with a nitrate-free interval each day to prevent tolerance.
- Avoid sudden changes in position (e.g., standing up quickly) to prevent dizziness or fainting.
- Avoid alcohol, as it can increase the blood pressure-lowering effects.
- Be aware that headache is a common side effect and often indicates the medication is working. It may lessen with continued use.
- Do not stop taking this medication suddenly without consulting your doctor.
- Inform your doctor or pharmacist about all other medications you are taking, especially erectile dysfunction drugs (e.g., Viagra, Cialis) as they are strictly contraindicated.
Available Forms & Alternatives
Available Strengths:
- Isosorbide Dinitrate 30mg Oral Tabs
- Isosorbide Dinitrate 5mg Oral Tabs
- Isosorbide Dinitrate 20mg Tablets
- Isosorbide Dinitrate 10mg Oral Tabs
- Isosorbide Mononitrate 10mg Tabs
- Isosorbide Mononitrate 120mg ER Tab
- Isosorbide Mononitrate 30mg ER Tabs
- Isosorbide Mononitrate 60mg ER Tabs
- Isosorbide Mononitrate 60mg ER Tabs
- Isosorbide Dinitrate 40mg Tablets
- Isosorbide Mononitrate 30mg ER Tabs
- Isosorbide Mononitrate 120mg ER Tab
- Isosorbide Mononitrate 20mg Tabs
- Isosorbide Mononitrate 20mg Tabs
- Isosorbide Mononitrate 10mg Tabs
Dosing & Administration
Adult Dosing
Standard Dose:
20 mg orally 2 to 3 times daily, with a 14-hour nitrate-free interval
Dose Range:
5 - 40 mg
Condition-Specific Dosing:
anginaProphylaxis:
Initial: 5-20 mg orally 2-3 times daily. Maintenance: 10-40 mg orally 2-3 times daily. Doses should be administered to allow for a 14-hour nitrate-free interval (e.g., 7 AM, 12 PM, 5 PM for a 3-dose regimen, or 7 AM, 12 PM for a 2-dose regimen).
acuteAngina:
Sublingual: 2.5-10 mg as needed for acute attack, repeat every 5-10 minutes for up to 3 doses.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment recommended, monitor for adverse effects.
Moderate:
No specific adjustment recommended, monitor for adverse effects.
Severe:
Use with caution; monitor for prolonged effects and adverse reactions due to potential accumulation of active metabolites. Consider lower starting doses.
Dialysis:
Not well studied; use with caution. Metabolites are renally excreted.
Hepatic Impairment:
Mild:
No specific adjustment recommended.
Moderate:
Use with caution; monitor for increased effects due to impaired metabolism. Consider lower starting doses.
Severe:
Use with caution; monitor for increased effects due to impaired metabolism. Consider lower starting doses.
Pharmacology
Mechanism of Action
Isosorbide dinitrate is an organic nitrate that acts as a vasodilator. It is metabolized to nitric oxide (NO) in vascular smooth muscle cells. NO activates guanylate cyclase, leading to an increase in cyclic guanosine monophosphate (cGMP). Increased cGMP causes dephosphorylation of myosin light chains, resulting in relaxation of vascular smooth muscle. This leads to venodilation (primary effect, reducing preload and myocardial oxygen demand) and, to a lesser extent, arterial dilation (reducing afterload). It also dilates coronary arteries, improving blood flow to ischemic areas.
Pharmacokinetics
Absorption:
Bioavailability:
Oral: 20-25% (due to significant first-pass metabolism); Sublingual: 50-60%
Tmax:
Oral: 1 hour; Sublingual: 6 minutes
FoodEffect:
Food may delay absorption but does not significantly affect the extent of absorption.
Distribution:
Vd:
Not readily available, but widely distributed.
ProteinBinding:
Not extensively protein bound (less than 10%).
CnssPenetration:
Limited
Elimination:
HalfLife:
Parent drug: 1 hour; Isosorbide-2-mononitrate: 1.5-2 hours; Isosorbide-5-mononitrate: 4-6 hours
Clearance:
High systemic clearance.
ExcretionRoute:
Renal (primarily as glucuronide conjugates of metabolites).
Unchanged:
<1% (parent drug)
Pharmacodynamics
OnsetOfAction:
Oral: 20-60 minutes; Sublingual: 2-5 minutes
PeakEffect:
Oral: 1-2 hours; Sublingual: 15-45 minutes
DurationOfAction:
Oral: 4-6 hours; Sublingual: 1-3 hours
Confidence:
Medium
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Attention Immediately
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical help right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Severe dizziness or fainting
Abnormal heartbeat, either fast or slow
Other Possible Side Effects
Like all medications, this drug can cause side effects. Although many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms that bother you or persist, contact your doctor for guidance:
Headaches, which may occur when you start taking this medication. In most cases, this side effect improves over time. Do not adjust your dosage without consulting your doctor, as they can suggest ways to minimize this symptom.
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects not mentioned here. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical help right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Severe dizziness or fainting
Abnormal heartbeat, either fast or slow
Other Possible Side Effects
Like all medications, this drug can cause side effects. Although many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms that bother you or persist, contact your doctor for guidance:
Headaches, which may occur when you start taking this medication. In most cases, this side effect improves over time. Do not adjust your dosage without consulting your doctor, as they can suggest ways to minimize this symptom.
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects not mentioned here. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe or persistent headache
- Dizziness, lightheadedness, or fainting spells
- Blurred vision
- Unusual weakness or fatigue
- Rapid or irregular heartbeat
- Worsening chest pain or new onset of chest pain
- Blue lips, fingernails, or skin (signs of methemoglobinemia, rare but serious)
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced.
Certain health conditions, including:
+ Heart failure (weak heart)
+ Recent heart attack
Current medications, particularly:
+ Avanafil
+ Riociguat
+ Sildenafil
+ Tadalafil
+ Vardenafil
Please note that this is not an exhaustive list of all potential interactions. To ensure your safety, it is crucial to discuss all of your:
Prescription and over-the-counter (OTC) medications
Natural products
Vitamins
* Health problems
with your doctor and pharmacist. They will help determine whether it is safe to take this medication in conjunction with your other medications and health conditions. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced.
Certain health conditions, including:
+ Heart failure (weak heart)
+ Recent heart attack
Current medications, particularly:
+ Avanafil
+ Riociguat
+ Sildenafil
+ Tadalafil
+ Vardenafil
Please note that this is not an exhaustive list of all potential interactions. To ensure your safety, it is crucial to discuss all of your:
Prescription and over-the-counter (OTC) medications
Natural products
Vitamins
* Health problems
with your doctor and pharmacist. They will help determine whether it is safe to take this medication in conjunction with your other medications and health conditions. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
If you are using this drug to manage chest pain, it is crucial to understand that it will not provide immediate relief during an attack. Instead, this medication is designed to help prevent or reduce the frequency of chest pain episodes. If you experience new or worsening chest pain or pressure, seek emergency medical attention immediately.
To ensure your safety, avoid driving and other activities that require alertness until you are familiar with how this medication affects you. To minimize the risk of dizziness or fainting, stand up slowly after sitting or lying down, and exercise caution when navigating stairs. Additionally, monitor your blood pressure and heart rate as directed by your doctor.
Before consuming alcohol, discuss its potential effects with your doctor. Long-term, uninterrupted use of this medication may lead to reduced effectiveness, a phenomenon known as tolerance. To avoid this, your doctor may recommend a daily "nitrate-free" period. If you notice this medication is no longer working as well as it should, consult your doctor; do not exceed the prescribed dosage.
If you are pregnant, planning to become pregnant, or breastfeeding, it is vital to discuss the potential benefits and risks of this medication with your doctor to make an informed decision about its use.
If you are using this drug to manage chest pain, it is crucial to understand that it will not provide immediate relief during an attack. Instead, this medication is designed to help prevent or reduce the frequency of chest pain episodes. If you experience new or worsening chest pain or pressure, seek emergency medical attention immediately.
To ensure your safety, avoid driving and other activities that require alertness until you are familiar with how this medication affects you. To minimize the risk of dizziness or fainting, stand up slowly after sitting or lying down, and exercise caution when navigating stairs. Additionally, monitor your blood pressure and heart rate as directed by your doctor.
Before consuming alcohol, discuss its potential effects with your doctor. Long-term, uninterrupted use of this medication may lead to reduced effectiveness, a phenomenon known as tolerance. To avoid this, your doctor may recommend a daily "nitrate-free" period. If you notice this medication is no longer working as well as it should, consult your doctor; do not exceed the prescribed dosage.
If you are pregnant, planning to become pregnant, or breastfeeding, it is vital to discuss the potential benefits and risks of this medication with your doctor to make an informed decision about its use.
Overdose Information
Overdose Symptoms:
- Severe hypotension (very low blood pressure)
- Persistent throbbing headache
- Palpitations
- Flushing
- Dizziness, vertigo
- Nausea, vomiting
- Diaphoresis (sweating)
- Syncope (fainting)
- Visual disturbances
- Methemoglobinemia (cyanosis, dyspnea, confusion, seizures, coma - rare but serious, especially with very high doses)
What to Do:
Seek immediate medical attention. Call 911 or your local emergency number. For suspected overdose, contact a poison control center at 1-800-222-1222. Management includes supportive care, elevation of legs, IV fluids for hypotension. For methemoglobinemia, methylene blue may be administered.
Drug Interactions
Contraindicated Interactions
- Phosphodiesterase-5 (PDE5) inhibitors (e.g., sildenafil, tadalafil, vardenafil, avanafil) - concurrent use can cause profound and prolonged hypotension, syncope, and myocardial infarction.
- Riociguat (soluble guanylate cyclase stimulator) - concurrent use can cause severe hypotension.
Major Interactions
- Other vasodilators (e.g., hydralazine, minoxidil) - additive hypotensive effects.
- Antihypertensive agents (e.g., beta-blockers, calcium channel blockers, ACE inhibitors, diuretics) - additive hypotensive effects.
- Alcohol - enhances hypotensive effects and may cause orthostatic hypotension.
Moderate Interactions
- Tricyclic antidepressants - may reduce the hypotensive effect of nitrates.
- Phenothiazines - may reduce the hypotensive effect of nitrates.
- Ergotamine - nitrates may antagonize the effects of ergotamine, potentially leading to increased angina.
Minor Interactions
- Not many specific minor interactions, but general caution with any drug that can lower blood pressure.
Monitoring
Baseline Monitoring
Blood Pressure (BP)
Rationale: To establish baseline and assess risk of hypotension.
Timing: Prior to initiation of therapy.
Heart Rate (HR)
Rationale: To establish baseline and assess for reflex tachycardia.
Timing: Prior to initiation of therapy.
Angina frequency and severity
Rationale: To assess the need for therapy and establish a baseline for efficacy monitoring.
Timing: Prior to initiation of therapy.
Routine Monitoring
Blood Pressure (BP)
Frequency: Regularly, especially during dose titration and if symptoms of hypotension occur.
Target: Maintain within patient's normal range, avoiding symptomatic hypotension.
Action Threshold: Systolic BP <90 mmHg or significant drop from baseline (>20 mmHg) or symptomatic hypotension (dizziness, syncope).
Heart Rate (HR)
Frequency: Regularly, especially during dose titration.
Target: Maintain within patient's normal range.
Action Threshold: Significant tachycardia or bradycardia.
Angina symptoms (frequency, severity, duration)
Frequency: Continuously by patient self-report.
Target: Reduction in angina episodes and severity.
Action Threshold: Worsening angina, new onset of angina, or inadequate control of symptoms.
Headache and other adverse effects (e.g., flushing, dizziness)
Frequency: Regularly, especially during initial therapy.
Target: Acceptable level of side effects.
Action Threshold: Intolerable side effects requiring dose adjustment or discontinuation.
Symptom Monitoring
- Headache (common, often indicates drug activity)
- Dizziness or lightheadedness (especially upon standing)
- Flushing (reddening of face/neck)
- Nausea/vomiting
- Weakness
- Palpitations
- Blurred vision
- Syncope (fainting)
- Worsening angina (paradoxical effect or tolerance development)
Special Patient Groups
Pregnancy
Category C. Animal studies have shown adverse effects, but there are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus.
Trimester-Specific Risks:
First Trimester:
Potential for fetal harm based on animal data; avoid if possible.
Second Trimester:
Use with caution; monitor maternal blood pressure.
Third Trimester:
Use with caution; monitor maternal blood pressure and fetal well-being.
Lactation
It is not known whether isosorbide dinitrate or its metabolites are excreted in human milk. Caution should be exercised when administered to a nursing woman. The American Academy of Pediatrics considers nitrates to be compatible with breastfeeding, but individual risk/benefit should be assessed.
Infant Risk:
L3 (Moderate risk) - Potential for hypotension in the infant. Monitor infant for signs of hypotension (lethargy, poor feeding).
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Use is generally not recommended.
Geriatric Use
Elderly patients may be more susceptible to the hypotensive effects of nitrates and may require lower initial doses and careful titration. Increased risk of falls due to orthostatic hypotension. Monitor blood pressure closely.
Clinical Information
Clinical Pearls
- Nitrate tolerance is a common issue with continuous use. To prevent this, a daily nitrate-free interval (typically 10-14 hours) is crucial. For a twice-daily regimen, this means taking doses approximately 7 hours apart (e.g., 8 AM and 3 PM).
- Headache is a very common side effect, especially at the beginning of therapy. It often indicates the drug is working and may decrease with continued use. OTC pain relievers can be used.
- Isosorbide dinitrate is used for prophylaxis of angina, not for acute relief of an ongoing attack (unless sublingual form is used). For acute relief, sublingual nitroglycerin is preferred.
- Patients should be educated on the absolute contraindication with PDE5 inhibitors (e.g., sildenafil, tadalafil) due to the risk of severe, life-threatening hypotension.
- Orthostatic hypotension is a significant risk. Advise patients to rise slowly from a sitting or lying position.
Alternative Therapies
- Isosorbide mononitrate (long-acting nitrate, active metabolite of ISDN)
- Nitroglycerin (sublingual, transdermal, oral extended-release)
- Beta-blockers (e.g., metoprolol, atenolol)
- Calcium channel blockers (e.g., amlodipine, diltiazem, verapamil)
- Ranolazine
- Coronary artery bypass grafting (CABG)
- Percutaneous coronary intervention (PCI)
Cost & Coverage
Average Cost:
$10 - $50 per 30 tablets (20mg generic)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (for generic formulations)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure safe and effective treatment, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it is a good idea to consult with your pharmacist. If you have any questions or concerns about this medication, do not hesitate to discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When seeking help, be prepared to provide detailed information about the overdose, including the medication taken, the amount, and the time it occurred.