Isosorbide dinitrate

Drug Information: Isosorbide dinitrate

Isosorbide dinitrate is a vasodilator medication used to prevent angina (chest pain) caused by heart disease. It belongs to a class of drugs known as nitrates, which work by relaxing blood vessels, allowing blood to flow more easily to the heart and reducing its workload. Isosorbide dinitrate can be administered sublingually for rapid relief of acute angina attacks or orally for longer-term prophylaxis. It’s important to use this medication as directed by a healthcare professional to avoid potential side effects and ensure its effectiveness.

Category

Vasodilator (including nitrates)

Mechanism of Action

Isosorbide dinitrate’s primary mechanism of action involves its conversion to nitric oxide (NO) within the body. This conversion is facilitated by enzymes present in vascular smooth muscle. Nitric oxide then activates guanylate cyclase, an enzyme that catalyzes the conversion of guanosine triphosphate (GTP) to cyclic guanosine monophosphate (cGMP). Increased levels of cGMP lead to the dephosphorylation of myosin light chains, causing relaxation of vascular smooth muscle. This relaxation results in vasodilation, primarily affecting veins. The dilation of veins reduces venous return to the heart (preload), decreasing the heart’s workload and oxygen demand. Additionally, dilation of coronary arteries improves blood flow to the heart muscle itself, further reducing angina. The drug is a prodrug.

Clinical Uses

Isosorbide dinitrate is primarily used for the management and prevention of angina pectoris. It’s effective in both acute treatment and long-term prophylaxis. In acute angina attacks, sublingual administration provides rapid relief by quickly dilating blood vessels and improving blood flow to the heart. For chronic angina, oral formulations are used to reduce the frequency and severity of chest pain episodes. Isosorbide dinitrate is also sometimes used in the treatment of heart failure, particularly in combination with other medications, due to its ability to reduce preload and afterload on the heart. Additionally, it can be used to treat esophageal spasms, although other treatments are often preferred.

Dosage

Adults:

• Sublingual: 2.5-10 mg every 2-3 hours as needed for acute angina.
• Oral: 5-40 mg 2-3 times daily. Extended-release formulations may be given once daily.

Pediatrics: Safety and efficacy not established in pediatric patients. Use is generally avoided.
Route of Administration: Sublingual (under the tongue) or oral (tablet).
Dosage must be individualized based on patient response and tolerance. Tolerance can develop with long-term use, requiring dosage adjustments. Consult a healthcare provider for specific dosage instructions.

Indications

Common indications for Isosorbide dinitrate include:

• Angina pectoris (prevention and treatment)
• Heart failure (adjunctive therapy)
• Esophageal spasm (less common)

Contraindications

Isosorbide dinitrate is contraindicated in the following conditions:

• Hypersensitivity to nitrates
• Concurrent use of phosphodiesterase-5 (PDE5) inhibitors (e.g., sildenafil, tadalafil, vardenafil) due to risk of severe hypotension.
• Severe anemia
• Closed-angle glaucoma
• Severe hypotension
• Increased intracranial pressure
• Hypertrophic obstructive cardiomyopathy

FAQ

1. What is Isosorbide dinitrate used for?
   
   Isosorbide dinitrate is primarily used to prevent and treat angina (chest pain) caused by reduced blood flow to the heart.
2. How does Isosorbide dinitrate work?
   
   It works by relaxing blood vessels, allowing more blood to flow to the heart and reducing its workload.
3. What are the common side effects of Isosorbide dinitrate?
   
   Common side effects include headache, dizziness, lightheadedness, and flushing.
4. Can I take Isosorbide dinitrate with other medications?
   
   It’s important to inform your doctor about all medications you are taking, especially PDE5 inhibitors (e.g., sildenafil), as they can cause a dangerous drop in blood pressure when taken with Isosorbide dinitrate.
5. How should I store Isosorbide dinitrate?
   
   Store Isosorbide dinitrate in a cool, dry place away from light and moisture. Keep out of reach of children.
6. What should I do if I experience a headache while taking Isosorbide dinitrate?
   
   Headaches are a common side effect. You can try taking an over-the-counter pain reliever like acetaminophen. If headaches are severe or persistent, consult your doctor.
7. How long does Isosorbide dinitrate take to work?
   
   Sublingual forms work quickly, usually within a few minutes, while oral forms take longer to take effect.
8. Can I drink alcohol while taking Isosorbide Dinitrate?
   
   Alcohol can enhance the hypotensive effects of Isosorbide Dinitrate. Avoid or limit alcohol consumption while taking this medication.