According to the FDA (2024), Nitroglycerin is the first-line treatment for the acute relief of angina pectoris due to its rapid onset of action.
A study published in the Journal of the American College of Cardiology (2022) emphasizes that a nitrate-free interval of 10-12 hours is essential to prevent pharmacological tolerance.
The American Heart Association (AHA) guidelines state that Nitroglycerin must not be administered to patients who have taken Sildenafil within 24 hours or Tadalafil within 48 hours.
Data from DailyMed (2024) confirms that sublingual nitroglycerin tablets lose potency rapidly if exposed to light or moisture, requiring storage in amber glass bottles.
The RALES trial and subsequent reviews have highlighted the importance of nitroglycerin in managing acute decompensated heart failure by reducing cardiac preload.
According to the National Institutes of Health (NIH), the half-life of nitroglycerin is remarkably short, typically between 1 and 4 minutes.
Research in the British Journal of Clinical Pharmacology (2023) indicates that mitochondrial aldehyde dehydrogenase (ALDH2) is the key enzyme responsible for nitroglycerin's bioactivation.
The FDA-approved labeling for Rectiv (2024) specifies a 0.4% concentration of nitroglycerin for the treatment of pain associated with chronic anal fissures.
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Nitro-dur, you must consult a qualified healthcare professional.
Nitroglycerin is a potent nitrate vasodilator primarily used for the acute relief and prophylactic management of angina pectoris. It functions by relaxing vascular smooth muscle, thereby reducing myocardial oxygen demand and improving coronary blood flow.
💊Usage & Dosage
Adult Dosage
Dosage for nitroglycerin is highly individualized based on the patient's response and the specific formulation used. Healthcare providers typically aim for the lowest effective dose to minimize side effects like headaches.
Sublingual Tablets: For acute angina, the standard dose is 0.3 mg, 0.4 mg, or 0.6 mg dissolved under the tongue at the first sign of an attack. This may be repeated every 5 minutes for a maximum of 3 doses in 15 minutes. If pain persists after the first dose, many protocols suggest seeking emergency medical care immediately.
Translingual Spray: 1 to 2 sprays (0.4 mg per spray) onto or under the tongue at the onset of pain. No more than 3 sprays should be used in a 15-minute period.
Transdermal Patch: Typically started at 0.2 mg/hr to 0.4 mg/hr. Patches are usually worn for 12 to 14 hours and then removed for a 10- to 12-hour 'nitrate-free' period to prevent the development of drug tolerance.
Topical Ointment: Usually applied as 0.5 to 2 inches of ointment twice daily, with a nitrate-free interval.
Intravenous Infusion: Started at 5 mcg/min and titrated upward by 5 mcg/min every 3–5 minutes based on clinical response and blood pressure monitoring.
Pediatric Dosage
Nitroglycerin is generally not approved for use in pediatric populations. Safety and effectiveness have not been established in children. In rare, specialized pediatric cardiac intensive care cases, it may be used off-label under the direct supervision of a pediatric cardiologist, but this is not standard practice.
Dosage Adjustments
Renal Impairment
Specific dosage adjustments for patients with kidney disease are generally not required for nitroglycerin, as it is rapidly metabolized by the liver and vascular tissues. However, patients with severe renal impairment should be monitored for fluid balance if receiving intravenous formulations.
Hepatic Impairment
Because the liver is a primary site of metabolism, patients with severe hepatic cirrhosis may have reduced clearance of nitroglycerin. Healthcare providers typically use caution and monitor blood pressure closely in these individuals, though specific dose-reduction formulas are not standardized.
Elderly Patients
Older adults are often more sensitive to the hypotensive (blood pressure lowering) effects of nitroglycerin. Clinical guidelines suggest starting at the lower end of the dosing range. There is an increased risk of falls due to dizziness (orthostatic hypotension) in this population.
How to Take Nitroglycerin
Proper administration is vital for the effectiveness of nitroglycerin:
1Sublingual Tablets: Do not swallow the tablet. Sit down before taking it to avoid falling if you become dizzy. Place the tablet under the tongue and let it dissolve completely. Do not eat, drink, or smoke while the tablet is dissolving.
2Translingual Spray: Do not shake the canister. Spray onto or under the tongue. Do not inhale the spray.
3Transdermal Patches: Apply to a clean, dry, hairless area of the upper body or upper arms. Rotate the application site daily to avoid skin irritation. Ensure the patch is removed at the time directed by your doctor to maintain the nitrate-free interval.
4Storage: Sublingual tablets are extremely sensitive to light and moisture. They must be kept in their original amber glass bottle. Do not put cotton or other medications in the bottle. Close the cap tightly immediately after use.
Missed Dose
For maintenance forms (patches or ointment), if you miss a dose, apply it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose. Do not apply two patches or a double dose of ointment to make up for a missed one, as this can cause dangerously low blood pressure.
Overdose
An overdose of nitroglycerin can cause severe hypotension (very low blood pressure) and methemoglobinemia (a condition where the blood cannot carry oxygen effectively).
Symptoms: Severe throbbing headache, confusion, fever, vertigo, palpitations, visual disturbances, vomiting, bloody diarrhea, fainting, and dyspnea (shortness of breath).
Emergency Measures: If an overdose is suspected, seek emergency medical attention immediately. Keep the patient lying down with legs elevated to support blood pressure. In the hospital, treatment may include intravenous fluids and, in the case of methemoglobinemia, methylene blue.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop taking this medication without medical guidance.
⚠️Side Effects
Common Side Effects (>1 in 10)
Side effects of nitroglycerin are primarily related to its mechanism as a vasodilator. Because it widens blood vessels throughout the body, not just in the heart, several predictable reactions occur:
Nitrate Headache: This is the most common side effect, affecting a large majority of patients. It is often described as a sharp or throbbing pain. It occurs because the blood vessels in the brain are also dilating. These headaches usually decrease in intensity and frequency as the body becomes accustomed to the medication over several days or weeks.
Flushing: A feeling of warmth, redness, or tingling in the face, neck, or chest.
Dizziness and Lightheadedness: Especially when standing up quickly from a sitting or lying position (orthostatic hypotension).
Less Common Side Effects (1 in 100 to 1 in 10)
🔴Warnings
Important Safety Information
Nitroglycerin is a potent medication that requires careful handling and adherence to safety protocols. Patients must be aware that while it is highly effective for chest pain, it can significantly alter blood pressure and interact with other substances. Always sit or lie down when taking fast-acting nitroglycerin to prevent injury from fainting.
Black Box Warnings
As of 2026, there are no FDA black box warnings for Nitroglycerin. However, clinical guidelines emphasize the extreme danger of mixing this drug with erectile dysfunction medications or certain pulmonary hypertension drugs.
Major Precautions
Hypotension and Shock: Nitroglycerin should not be used in patients with very low blood pressure, severe dehydration (volume depletion), or those in cardiogenic shock. It can worsen these conditions by further reducing the return of blood to the heart.
🔄Interactions
Contraindicated Combinations (Do Not Use Together)
The following medications must NEVER be used with Nitroglycerin. The interaction is considered life-threatening:
PDE5 Inhibitors (Sildenafil, Tadalafil, Vardenafil, Avanafil): These drugs (commonly used for erectile dysfunction or pulmonary hypertension) inhibit the breakdown of cGMP. Since nitroglycerin increases cGMP production, the combination leads to an uncontrolled accumulation of cGMP, resulting in profound, irreversible vasodilation and fatal hypotension.
Riociguat (Adempas): Used for pulmonary hypertension. Similar to PDE5 inhibitors, it works on the same pathway as nitroglycerin and can cause severe low blood pressure.
Serious Interactions (Monitor Closely)
Antihypertensive Medications
🚫Contraindications
Absolute Contraindications
In certain clinical situations, the risks of nitroglycerin far outweigh any potential benefits. It must NEVER be used in the following cases:
Use of PDE5 Inhibitors: As detailed in the interactions section, use of sildenafil, tadalafil, or vardenafil within the last 24 to 48 hours is an absolute contraindication due to the risk of fatal hypotension.
Severe Anemia: In patients with very low red blood cell counts, the blood's ability to carry oxygen is already compromised. Nitroglycerin-induced vasodilation can further reduce oxygen delivery to vital organs.
Increased Intracranial Pressure: Because nitroglycerin dilates cerebral blood vessels, it can dangerously increase pressure within the skull, potentially leading to brain injury in patients with existing trauma or hemorrhage.
Hypersensitivity/Allergy: Any known allergy to nitroglycerin, other nitrates, or any of the inactive ingredients (such as the adhesives in patches) is a contraindication.
👥Special Populations
Pregnancy
Nitroglycerin is classified by the FDA as Pregnancy Category C. This means that animal reproduction studies have shown an adverse effect on the fetus, or there are no adequate and well-controlled studies in humans.
Risks: It is not known whether nitroglycerin can cause fetal harm when administered to a pregnant woman. However, severe maternal hypotension caused by the drug could reduce blood flow to the placenta, potentially harming the fetus.
Clinical Use: Nitroglycerin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. It is generally reserved for severe, life-threatening cardiovascular situations where other treatments have failed.
Breastfeeding
It is not known whether nitroglycerin is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when nitroglycerin is administered to a nursing woman. Given the extremely short half-life of the drug, the risk to the infant may be low, but healthcare providers typically recommend monitoring the infant for signs of low blood pressure or irritability if the mother is using the medication.
🧬Pharmacology
Mechanism of Action
Nitroglycerin is a potent vasodilator that acts through the exogenous supply of nitric oxide (NO). The molecular pathway involves several steps:
1Bioactivation: Nitroglycerin is a prodrug that enters vascular smooth muscle cells. It is then converted to nitric oxide by the enzyme mitochondrial aldehyde dehydrogenase (ALDH2).
2Activation of Guanylyl Cyclase: The released nitric oxide binds to the heme group of soluble guanylyl cyclase (sGC).
3cGMP Production: This binding activates the enzyme, which converts GTP (guanosine triphosphate) to cGMP (cyclic guanosine monophosphate).
4Protein Kinase Activation
Frequently Asked Questions
Common questions about Nitro-dur
What is Nitroglycerin used for?
Nitroglycerin is primarily used to treat and prevent angina pectoris, which is chest pain caused by a lack of oxygen-rich blood flow to the heart muscle. It is also used in emergency medical settings to treat acute heart failure and dangerously high blood pressure. In its rectal ointment form, it is used to relieve pain associated with chronic anal fissures. The drug works by relaxing and widening blood vessels, which allows blood to flow more easily and reduces the workload on the heart. It is a critical rescue medication for people with known coronary artery disease.
What are the most common side effects of Nitroglycerin?
The most common side effect of nitroglycerin is a headache, often referred to as a 'nitrate headache,' which is caused by the dilation of blood vessels in the brain. Other frequent side effects include flushing of the face and neck, dizziness, and lightheadedness, especially when standing up quickly. Some patients may also experience a rapid heartbeat (tachycardia) or a temporary feeling of weakness. These side effects are usually most intense when first starting the medication and often diminish as the body adjusts. If side effects become severe or persistent, you should contact your healthcare provider.
Can I drink alcohol while taking Nitroglycerin?
No, you should avoid drinking alcohol while taking nitroglycerin. Both alcohol and nitroglycerin cause blood vessels to dilate (widen), which can lead to a dangerously large drop in blood pressure when used together. This combination can cause severe dizziness, fainting, or even cardiovascular collapse. Even small amounts of alcohol can increase the risk of these side effects. If you have consumed alcohol, it is important to be extremely cautious and inform emergency medical personnel if you require nitroglycerin for chest pain.
Is Nitroglycerin safe during pregnancy?
Nitroglycerin is classified as Pregnancy Category C, meaning its safety in human pregnancy has not been well-established. Animal studies have shown potential risks, and there is a concern that severe drops in maternal blood pressure could reduce blood flow to the baby. Because of this, nitroglycerin is only used during pregnancy if the potential benefit to the mother clearly outweighs the potential risk to the fetus. If you are pregnant or planning to become pregnant, you must discuss the risks and benefits of this medication with your cardiologist and obstetrician.
How long does it take for Nitroglycerin to work?
The onset of action for nitroglycerin depends on the form being used. Sublingual tablets and translingual sprays are designed for rapid relief and typically begin working within 1 to 3 minutes, with the maximum effect occurring around 5 minutes. Topical ointments usually take 30 to 60 minutes to begin working, while transdermal patches have a slow onset and are used for long-term prevention rather than immediate relief. If you are using a fast-acting form and your chest pain does not improve within 5 minutes of the first dose, you should seek emergency medical help immediately.
Can I stop taking Nitroglycerin suddenly?
You should never stop taking maintenance nitroglycerin, such as transdermal patches or daily ointments, without first consulting your doctor. Abruptly stopping the medication after long-term use can cause 'rebound' angina, where chest pain returns more frequently or more severely than before. In some cases, sudden discontinuation can even trigger a heart attack. If you need to stop the medication, your healthcare provider will usually provide a plan to gradually reduce your dose over several days or weeks to ensure your heart remains stable.
What should I do if I miss a dose of Nitroglycerin?
If you miss a dose of a maintenance form of nitroglycerin, such as a patch or ointment, apply it as soon as you remember. However, if it is nearly time for your next scheduled dose, skip the missed dose and return to your regular schedule. Do not apply extra medication or two patches at once to make up for a missed dose, as this can lead to dangerously low blood pressure. For the sublingual tablets used for acute pain, there is no 'missed dose' since they are only taken as needed for chest pain.
Does Nitroglycerin cause weight gain?
Nitroglycerin is not known to cause weight gain. It does not affect metabolism, appetite, or water retention in a way that would lead to an increase in body mass. If you experience sudden weight gain or swelling (edema) while taking nitroglycerin, it is more likely related to an underlying heart condition, such as heart failure, rather than the medication itself. You should report any rapid weight gain or swelling in your ankles or legs to your doctor immediately, as this may indicate that your heart condition requires a change in treatment.
Can Nitroglycerin be taken with other medications?
Nitroglycerin has several significant drug interactions that must be managed by a doctor. It should never be taken with PDE5 inhibitors (like Viagra or Cialis) or riociguat, as the combination can be fatal. It can also interact with other blood pressure medications, antidepressants, and even some over-the-counter NSAIDs. Always provide your healthcare provider with a complete list of all prescription drugs, over-the-counter medicines, vitamins, and herbal supplements you are taking. This allows your doctor to monitor for potential interactions and adjust your treatment plan for safety.
Is Nitroglycerin available as a generic?
Yes, nitroglycerin is available in several generic forms, which are typically much less expensive than brand-name versions. Generic sublingual tablets, transdermal patches, and ointments are widely available and are required by the FDA to have the same active ingredient, strength, and effectiveness as the brand-name products. When picking up your prescription, you can ask your pharmacist if a generic version is available for the specific form your doctor has prescribed. Regardless of whether you use a brand or generic, ensure the sublingual tablets are stored in their original glass container.
Similar Medications
Other drugs with the same active ingredient (Nitroglycerin)
Tachycardia: A rapid or pounding heartbeat. This occurs as a reflex reaction by the body to compensate for the drop in blood pressure.
Nausea and Vomiting: Some patients experience gastrointestinal upset shortly after administration.
Weakness: A general feeling of lethargy or lack of energy.
Skin Irritation: Specifically with patches or ointments, patients may develop redness, itching, or a rash at the site of application.
Rare Side Effects (less than 1 in 100)
Syncope: Fainting due to a sudden, severe drop in blood pressure.
Methemoglobinemia: A rare but life-threatening condition where the iron in hemoglobin is oxidized, preventing it from releasing oxygen to tissues. Symptoms include bluish skin (cyanosis), fatigue, and shortness of breath.
Exfoliative Dermatitis: A severe, widespread redness and peeling of the skin.
Paradoxical Bradycardia: In rare cases, nitroglycerin can cause the heart rate to slow down rather than speed up, which may worsen chest pain.
Serious Side Effects — Seek Immediate Medical Attention
> Warning: Stop using Nitroglycerin and call your doctor or emergency services immediately if you experience any of the following:
1Signs of an Allergic Reaction: Hives, difficulty breathing, swelling of your face, lips, tongue, or throat.
2Severe Hypotension: Extreme dizziness, feeling like you might pass out, or blurred vision.
3Worsening Chest Pain: If the pain becomes more frequent, severe, or lasts longer than usual (this could indicate unstable angina or a heart attack).
4Signs of Methemoglobinemia: Bluish color of the lips, fingernails, or palms of the hands; dark or chocolate-colored blood; extreme fatigue.
5Severe Throbbing Headache: If the headache does not improve with over-the-counter pain relievers or becomes unbearable.
Long-Term Side Effects
Nitrate Tolerance: The most significant long-term issue with nitroglycerin is the development of tolerance. If the drug is present in the bloodstream 24 hours a day, the body stops responding to it. This is why a 'nitrate-free' period of 10–12 hours daily is mandatory for long-term use.
Dependency: While not addictive in the traditional sense, sudden discontinuation after long-term use can cause 'rebound' angina, where chest pain returns more severely than before.
Black Box Warnings
No FDA black box warnings are currently issued for nitroglycerin. However, there is a Contraindication Warning that is treated with similar clinical gravity: Nitroglycerin must NEVER be used in combination with phosphodiesterase-5 (PDE5) inhibitors such as sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra). This combination can cause a sudden and catastrophic drop in blood pressure that may be fatal.
Report any unusual symptoms to your healthcare provider. Many side effects, like the 'nitrate headache,' can be managed by adjusting the dose or using mild analgesics (painkillers) as recommended by your doctor.
Increased Intracranial Pressure: Because nitroglycerin dilates blood vessels in the brain, it can increase the pressure inside the skull. It is generally avoided in patients with recent head trauma or brain hemorrhage.
Severe Anemia: Patients with severe anemia may not have enough functional hemoglobin to benefit from the increased blood flow, and nitroglycerin may worsen the symptoms of oxygen deprivation.
Glaucoma: While previously thought to be a major concern, nitroglycerin can be used with caution in patients with open-angle glaucoma. However, it is generally contraindicated in those with closed-angle glaucoma because it may increase intraocular pressure.
Hypertrophic Cardiomyopathy (HOCM): In patients with this specific heart condition, nitroglycerin can worsen the obstruction of blood leaving the heart, leading to severe fainting or increased pain.
Monitoring Requirements
If you are taking nitroglycerin long-term or receiving it intravenously, your healthcare provider will monitor several parameters:
Blood Pressure and Heart Rate: Frequent monitoring is required to ensure the dose is effective without causing excessive hypotension or reflex tachycardia.
Pain Frequency: Keeping a log of how often you use sublingual nitroglycerin helps your doctor determine if your heart disease is progressing.
Methemoglobin Levels: In patients receiving high-dose intravenous infusions for long periods, blood tests may be performed to check for methemoglobinemia.
Driving and Operating Machinery
Nitroglycerin can cause significant dizziness, lightheadedness, and blurred vision, especially during the first few days of treatment or when the dose is increased. You should not drive or operate heavy machinery until you know how the medication affects you. Alcohol can significantly worsen these effects.
Alcohol Use
Alcohol consumption is strongly discouraged while using nitroglycerin. Alcohol also dilates blood vessels and lowers blood pressure. When combined with nitroglycerin, the effect is additive, potentially leading to severe hypotension, fainting, and collapse.
Discontinuation
Do not stop taking maintenance nitroglycerin (like patches or long-acting capsules) suddenly. Abruptly stopping the medication can lead to a 'rebound effect,' causing severe chest pain or even a heart attack. If the medication needs to be stopped, your doctor will provide a schedule to gradually taper the dose.
> Important: Discuss all your medical conditions, including any history of low blood pressure, anemia, or glaucoma, with your healthcare provider before starting Nitroglycerin.
: Drugs used to treat high blood pressure, such as beta-blockers, calcium channel blockers, ACE inhibitors, and diuretics, can have an additive effect with nitroglycerin. This increases the risk of severe hypotension and fainting.
Ergotamine and Related Drugs: Nitroglycerin can increase the blood levels of ergotamine (used for migraines), potentially leading to ergotism (a condition where blood flow to the limbs is restricted).
Heparin: Intravenous nitroglycerin has been shown to reduce the anticoagulant (blood-thinning) effect of heparin. Patients receiving both may require more frequent monitoring of their aPTT (blood clotting time) and dosage adjustments of heparin.
Moderate Interactions
NSAIDs (Nonsteroidal Anti-inflammatory Drugs): Some studies suggest that NSAIDs like ibuprofen or naproxen might slightly reduce the vasodilatory effect of nitrates, though this is usually not clinically significant for most patients.
Tricyclic Antidepressants: Medications like amitriptyline can cause dry mouth, which may interfere with the dissolution of sublingual nitroglycerin tablets.
Food Interactions
Alcohol: As previously mentioned, alcohol significantly enhances the blood-pressure-lowering effects of nitroglycerin, increasing the risk of fainting and dangerous falls.
High-Fat Meals: While not an issue for sublingual or transdermal forms, high-fat meals can affect the absorption of certain oral extended-release nitrate capsules (though nitroglycerin is rarely used in this form today compared to isosorbide).
Herbal/Supplement Interactions
Hawthorn: This herb is sometimes used for heart health but can lower blood pressure. Taking it with nitroglycerin may increase the risk of hypotension.
Arginine: This amino acid is a precursor to nitric oxide. Taking arginine supplements with nitroglycerin may theoretically increase the risk of side effects like headaches and low blood pressure.
St. John's Wort: While it primarily affects drugs metabolized by CYP enzymes, it is always best to inform your doctor of its use due to the complexity of cardiovascular care.
Lab Test Interactions
Nitroglycerin may interfere with the Zlatkis-Zak color reaction, potentially resulting in falsely low serum cholesterol readings in laboratory tests. It does not typically affect standard blood counts or liver/kidney function tests.
Interaction Management Strategy
Mechanism: Most nitroglycerin interactions are 'pharmacodynamic,' meaning the drugs have similar or opposing effects on the body's systems (specifically blood pressure regulation).
Consequence: The primary risk is 'Toxicity' in the form of excessive hypotension.
Management: Healthcare providers manage this by reviewing a full list of the patient's medications, adjusting doses of blood pressure meds, and strictly forbidding the use of PDE5 inhibitors.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking, including those for erectile dysfunction or pulmonary hypertension.
Closed-Angle Glaucoma: Nitroglycerin may increase intraocular pressure, which can lead to permanent vision loss in patients with this specific, narrow-angle form of glaucoma.
Relative Contraindications
In these situations, a healthcare provider must carefully weigh the risks and benefits before prescribing nitroglycerin:
Hypertrophic Cardiomyopathy (HOCM): Nitroglycerin can decrease the volume of blood in the heart's ventricles, which in HOCM patients can cause the heart muscle to block the flow of blood out to the body.
Recent Myocardial Infarction (Heart Attack): While often used in heart attacks, it must be avoided if an 'inferior wall MI' with right ventricular involvement is suspected, as it can cause a catastrophic drop in blood pressure.
Volume Depletion (Dehydration): Patients who are severely dehydrated or on high doses of diuretics are at much higher risk for severe hypotension.
Constrictive Pericarditis or Pericardial Tamponade: Conditions where the heart is compressed by the surrounding sac; nitroglycerin can further reduce the heart's ability to fill with blood.
Cross-Sensitivity
Patients who have had an allergic reaction to other nitrate medications, such as Isosorbide Mononitrate or Isosorbide Dinitrate, are highly likely to be allergic to nitroglycerin as well. This is known as cross-sensitivity within the nitrate class. Additionally, some patients may be sensitive to the adhesives used in transdermal patches or the lanolin found in some nitroglycerin ointments.
> Important: Your healthcare provider will evaluate your complete medical history, including any recent head injuries or specific eye conditions, before prescribing Nitroglycerin.
Pediatric Use
Nitroglycerin is not approved for use in children. The safety, efficacy, and appropriate dosing for pediatric patients have not been established. Clinical use in children is extremely rare and limited to highly specialized cardiac intensive care environments under the direction of experts.
Geriatric Use
Patients aged 65 and older represent a significant portion of nitroglycerin users, but they require special consideration:
Hypotension Risk: Elderly patients are much more likely to experience significant drops in blood pressure and fainting (syncope) when taking nitrates.
Fall Risk: Dizziness from nitroglycerin is a major contributor to falls in the elderly, which can lead to fractures and other serious injuries.
Pharmacokinetics: While the metabolism of nitroglycerin is generally not affected by age, the presence of other age-related conditions (like kidney or liver decline) and the use of multiple other medications (polypharmacy) increase the risk of adverse effects.
Dosing: Doctors typically 'start low and go slow,' beginning with the smallest possible dose and monitoring blood pressure closely.
Renal Impairment
For patients with kidney disease, nitroglycerin is generally considered safe because it is primarily metabolized by the liver and blood vessels. However, the inactive ingredients in intravenous formulations (like propylene glycol) can accumulate in patients with severe renal failure if given in very high doses for long periods. Standard sublingual and transdermal doses do not require adjustment for GFR (glomerular filtration rate).
Hepatic Impairment
Since the liver is a major site of nitroglycerin metabolism, patients with severe liver disease (Child-Pugh Class C) may have higher levels of the drug in their system for longer periods. This increases the risk of side effects. Healthcare providers will monitor these patients closely for signs of excessive vasodilation and may reduce the frequency or dose of the medication.
> Important: Special populations require individualized medical assessment. Always inform your doctor if you are pregnant, planning to become pregnant, or are breastfeeding.
: cGMP activates cGMP-dependent protein kinases (PKG).
5Dephosphorylation: PKG leads to the dephosphorylation of myosin light chains and a reduction in intracellular calcium levels.
6Relaxation: The result is the relaxation of the smooth muscle, leading to vasodilation.
Pharmacodynamics
The pharmacodynamic response to nitroglycerin is dose-dependent. At low doses, it primarily dilates the veins, reducing the amount of blood returning to the heart (preload). This is the primary way it relieves angina. At higher doses, it also dilates the arteries, reducing the resistance the heart must pump against (afterload).
Tolerance: A key pharmacodynamic feature is the rapid development of tachyphylaxis (tolerance). Continuous exposure leads to the depletion of sulfhydryl groups or the inactivation of ALDH2, making the drug less effective. This is why a nitrate-free interval is clinically essential.
| Metabolism | Hepatic (Glutathione-organic nitrate reductase) and Vascular |
| Excretion | Renal (as metabolites) |
Chemical Information
Molecular Formula: C3H5N3O9
Molecular Weight: 227.09 g/mol
Solubility: Slightly soluble in water; highly soluble in alcohol, ether, and chloroform.
Structure: Nitroglycerin is a heavy, colorless, oily explosive liquid obtained by nitrating glycerol. In pharmaceutical form, it is diluted in non-explosive excipients to ensure safety.
Drug Class
Nitroglycerin is the prototypical member of the Nitrate Vasodilator class. Related medications include Isosorbide Mononitrate and Isosorbide Dinitrate. While they share the same mechanism, nitroglycerin is unique for its rapid onset and short duration, making it the preferred choice for acute rescue therapy.