Isosorbide Dinitrate Pharmacology

Isosorbide Dinitrate

About Isosorbide Dinitrate
Alkyl nitrate derivative, a direct vasodilator, Antianginal.
Mechanism of Action of Isosorbide Dinitrate
It is a direct smooth muscle relaxant, which have a prominent action vascular smooth muscles preferentially veins than arteries. It is enzymatically denitrated in the smooth muscle cells to release the reactive free radical nitric oxide which activates cytosolic guanylyl cyclase thus increases cyclic GMP levels which causes dephosphorylation of myosin light chain kinase(MLCK) through a cyclic GMP dependent protein kinase. Reduced availability of phosphorylated (active) MLCK interferes with activation of myosin and myosin fails to interact with actin to cause contraction and consequently relaxation occurs. Elevated levels of cyclic GMP also reduce calcium entry which also contributing to relaxation. It dilates veins more than arteries because veins have greater amount of enzyme that generate nitric oxide from nitrates. It also preferentially dilates epicardial arteries than autoregulatory arteries duo to defferential distribution of nitrate metabolizing enzymes in these vessels.
It causes preload reduction, slight decrease in after load, and preferential relaxation of larger conducting coronary arteries and is used as an effective drug in the management of both angina and congestive heart failure.

Pharmacokinets of Isosorbide Dinitrate
Absorption: Well absorbed orally, But bioavailability is reduced due to first pass metabolism.
Distribution: Widely distributed in the body.
Metabolism: Metabolized in liver to active metabolites.
Excretion: Excreted mainly through urine.
Onset of Action for Isosorbide Dinitrate
Sub lingual: 3 minutes
Oral: 30 minutes
Duration of Action for Isosorbide Dinitrate
Sub lingual: Half to Two hours
Oral: 5 to 6 hours
Half Life of Isosorbide Dinitrate
Sub lingual: 2 hours
Oral: 5 to 6 hours
Side Effects of Isosorbide Dinitrate
1. Headache
2. Weakness
3. Dizziness
4. Methaemoglobinaemia
5. Flushing
6. Palpitation
7. Orthostatic hypotension
8. Sweating
9. Sub lingual burning
10. Rashes

Contra-indications of Isosorbide Dinitrate
1. Myocardial infarction
2. Hypersensitivity to nitrates
3. Severe hypotension
4. Shock
5. Along with phosphodiesterase inhibitors

Special Precautions while taking Isosorbide Dinitrate
1. Gradually withdraw the drug with caution
2. Hypotension
3. Blood volume depletetion
4. Cerebral haemorrhage
5. Glaucoma
6. Sidenafil causes dangerous potentiation of action hypotension myocardial infarction and death

Pregnancy Related Information
Use with caution
Old Age Related Information
Use with caution
Breast Feeding Related Information
Use with caution
Children Related Information
Indications for Isosorbide Dinitrate
1. Classical angina
2. Variant angina
3. Adjunctive treatment of heart failure
4. Esophageal spasm without gastroesophagial reflux.

Interactions for Isosorbide Dinitrate
Alcohol: Severe hypotension and cardiovascular collapse.
Aspirin: Increase serum concentrations of nitrates and their actions.
Antihypertensives, TCAs, Phenothiazine, Calcium channel blockers: Marked symptomatic orthostatic hypotension.
Lab Tests: May interfere with the Zlatkis-Zak colour reaction causing a false report of decreased serum cholesterol.
Typical Dosage for Isosorbide Dinitrate
Sublingual form: 2.5 to 10mg. Repeated every 2 to 3 hours during acute phase or every 4 to 6 hours for prophylaxis.
Chewable form: Starts with 5mg test dose and increased up to 10mg as required for acute attack or every 2 to 3 hours for prophylaxis.
Oral form: 10 to 20mg three to four times daily for prophylaxis
Extended release form: 20 to 40mg 2 - 3 times daily.

Schedule of Isosorbide Dinitrate
Storage Requirements for Isosorbide Dinitrate
Store in a cool place away from flame and heat and protects from moisture in a tightly closed container.
Effects of Missed Dosage of Isosorbide Dinitrate
Take the missed dose as soon as remember and If it is the time for next dose then skip the missed dose and take the regular dose.
Effects of Overdose of Isosorbide Dinitrate
Treatment is supportive and symptomatic. Remove drug from the body by gastric lavage and administer activated charcoal to reduce absorption. Monitor blood gas measurements and methemoglobin levels. Supportive measures include respiratory support and oxygen administration. Recumbent positioning and passive movements of the extremities aid venous return. Maintain adequate body temperature and administer I.V. fluids. Administer adrenergic agonist like phenylephrine if required. For Methaemoglobinaemia; methylene blue may be given.

Home Delivery for Isosorbide Dinitrate in Your City

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However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for isosorbide dinitrate and other medicines and health products. Home delivery services for isosorbide dinitrate may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take isosorbide dinitrate only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for isosorbide dinitrate before they complete the sale. You can get this information while placing the order for isosorbide dinitrate with the pharmacy.

Isosorbide Dinitrate is a generic medicine name and there are several brands available for it. Some of the brands for isosorbide dinitrate might be better known than isosorbide dinitrate itself. If the pharmacy that's willing to deliver medicines to your home doesn't have isosorbide dinitrate in stock, you can ask for one of the branded alternatives for isosorbide dinitrate.