isosorbide mononitrate

Action and Spectrum

Actions and Spectrum: 

Action: Drug works by dilating the blood vessels, particularly the veins, leading to a reduction in venous return (preload) to the heart. This decreases the amount of blood returning to the heart, reducing the workload on the heart muscle and improving oxygen supply to the heart. The medication also causes dilation of coronary arteries, which enhances blood flow to the heart muscle itself, further improving oxygen delivery.  

Spectrum: Drug is primarily indicated for the treatment and prevention of angina pectoris, including chronic stable angina, vasospastic angina (Prinzmetal’s angina), and unstable angina. It is also used to reduce the frequency and severity of angina attacks.

Drug Interaction

Adverse Reaction

Frequency not defined  

Vomiting 

Tachycardia 

Syncope 

Restlessness 

Palpitations 

Orthostatic hypotension 

Nausea 

Methemoglobinemia 

Hypotension 

Headache 

Flushing 

Dizziness 

Black Box Warning

Black Box Warning:  

None

Contraindication / Caution

Contraindication/Caution:  

Hypersensitivity or Allergy: Individuals who experience a hypersensitivity or allergic reaction to isosorbide mononitrate or any of its constituent ingredients should refrain from using this medication. 

Hypotension (Low Blood Pressure): Drug can cause a drop in blood pressure. If you already have low blood pressure, using this medication may further decrease your blood pressure, leading to symptoms like dizziness, lightheadedness, or fainting. 

Increased Intracranial Pressure: isosorbide mononitrate can increase intracranial pressure, which is the pressure inside the skull. It is contraindicated in individuals with conditions such as cerebral hemorrhage (bleeding in the brain) or head trauma, as it may worsen these conditions. 

Concurrent Use of PDE5 Inhibitors: isosorbide mononitrate should not be used concurrently with phosphodiesterase type 5 (PDE5) inhibitors like sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra). Both medications can lower blood pressure, and their combined use can lead to a significant drop in blood pressure, which can be dangerous. 

Cardiogenic Shock: isosorbide mononitrate is contraindicated in patients with cardiogenic shock, a condition characterized by severe heart failure resulting in inadequate blood flow to the body’s organs. 

Severe Anemia: Individuals with severe anemia should avoid using isosorbide mononitrate, as it can further reduce the oxygen-carrying capacity of the blood. 

Pregnancy / Lactation

Pregnancy warnings:     

Pregnancy category: C 

Lactation: Excreted into human milk is unknown 

Pregnancy Categories:         

Category A: Studies that were well-controlled and met expectations revealed no risk to the fetus in either the first or second trimester. 

Category B: There were a lack of studies on pregnant women and no evidence of risk to the fetus in animal experiments.   

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.   

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category

Pharmacology

Pharmacology: 

isosorbide mononitrate is a medication primarily prescribed for the management of angina pectoris, a condition marked by chest pain or discomfort caused by decreased blood flow to the cardiac muscles. 

Pharmacodynamics: 

Isosorbide mononitrate is a prodrug, which means it undergoes biotransformation in the body to its active form, isosorbide-5-mononitrate (ISMN). ISMN is a potent vasodilator that acts by releasing nitric oxide (NO) in smooth muscle cells. Nitric oxide activates guanylate cyclase, leading to the production of cyclic guanosine monophosphate (cGMP).

Increased levels of cGMP promote relaxation of smooth muscle in blood vessels, particularly in the veins. This relaxation causes dilation of both arterial and venous blood vessels, leading to decreased peripheral resistance and venous pooling, resulting in reduced cardiac workload and improved oxygen supply to the heart.    

Pharmacokinetics: 

Absorption 

Drug is rapidly and almost completely absorbed from the gastrointestinal tract after oral administration. The peak plasma concentration is reached within 30-60 minutes. 

Distribution 

Drug is extensively distributed throughout the body. It undergoes significant first-pass metabolism in the liver, resulting in a low bioavailability (about 10-30%). It is primarily bound to plasma proteins. 

Metabolism 

Drug undergoes extensive metabolism in the liver, primarily via denitration, to form the active metabolite, isosorbide-5-mononitrate (ISM-5). ISM-5 is responsible for the pharmacological effects of isosorbide mononitrate. The metabolism of isosorbide mononitrate is subject to genetic polymorphism, which may affect its pharmacokinetics in certain individuals. 

Excretion and Elimination 

The elimination half-life of isosorbide mononitrate is approximately 4-5 hours. It is primarily eliminated from the body through hepatic metabolism and subsequent renal excretion of metabolites. A minimal fraction of the administered dose is eliminated in its original form through urine, accounting for less than 1%. 

Adminstartion

Administration:  

The appropriate dosage of isosorbide mononitrate can vary depending on the individual’s condition and response to treatment. It is essential to follow the specific instructions provided by your healthcare provider. 

Isosorbide mononitrate is typically taken orally, and the dosing frequency may vary. Some forms of the medication are taken once a day, while others may require multiple daily doses.

Patient Information Leaflet

Patient information leaflet 

Generic Name: isosorbide mononitrate 

Why do we use isosorbide mononitrate?  

Angina pectoris: isosorbide mononitrate is commonly prescribed to relieve and prevent episodes of angina. By reducing the workload on the heart, it can relieve chest pain, improve exercise tolerance, and decrease the frequency and severity of angina attacks. 

Chronic heart failure: isosorbide mononitrate may be used as part of the treatment regimen for chronic heart failure. It can help improve symptoms by reducing the strain on the heart and increasing blood flow to the organs. 

Anal fissures: isosorbide mononitrate has also been used topically in the form of an ointment or cream to treat anal fissures, which are small tears in the lining of the anus.