Glyceryl Trinitrate Pharmacology

Glyceryl Trinitrate

About Glyceryl Trinitrate
A vasodilator, Antianginal,in CHF.
Mechanism of Action of Glyceryl Trinitrate
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 differential 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 angina treatment.

Pharmacokinets of Glyceryl Trinitrate
Absorption: Well absorbed orally, But bioavailability is reduced due to first pass metabolism.
Distribution: Widely distributed in the body.
Metabolism: Metabolized in liver.
Excretion: Excreted mainly through urine as metabolites.
Onset of Action for Glyceryl Trinitrate
Sub lingual: 1 to 3 minutes
I.V.: 1 to 2 minutes
Topical: 30 to 60 minutes
Sustained release: 20 to 45 minutes
Duration of Action for Glyceryl Trinitrate
Sub lingual: 30 to 60 minutes
I.V.: 3 to 5 minutes
Topical: 2 to 12hours
Sustained release: 3to 8hours
Half Life of Glyceryl Trinitrate
Side Effects of Glyceryl Trinitrate
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 Glyceryl Trinitrate
1. Hypersensitivity to nitrates
2. Severe hypotension
3. Shock
4. Hypertrophic cardiomyopathy
5. Cerebral haemorrhage
6. Early Myocardial infarction(sub lingual)
7. Anaemia
8. Along with phosphodiesterase inhibitors.

Special Precautions while taking Glyceryl Trinitrate
1. Gradually withdraw the drug with caution, start therapy with lower doses
2. Hypotension
3. Blood volume depletion
4. Cardio vascular diseases
5. Pulmonary diseases
6. Glaucoma

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 Glyceryl Trinitrate
1. Angina pectoris
2. Unstable angina
3. Heart failure
4. Myocardial infarction
5. Hypertension

Interactions for Glyceryl Trinitrate
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.
Sidenafil causes dangerous potentiation of hypotension, myocardial infarction and death
Lab Tests: May interfere with the Zlatkis-Zak colour reaction causing a false report of decreased serum cholesterol.
Typical Dosage for Glyceryl Trinitrate
Tablets: 0.5mg at every 3 minutes until therapeutic effect is obtained.
I.V.: 5mcg/minute as infusion. Increase with increments of same dose
Sustained release Formulations: 2.5 to 6.5mg two to three times daily.
Topical: 1.5 to 3cm rubs on three times daily. Use more times if required.

Schedule of Glyceryl Trinitrate
Storage Requirements for Glyceryl Trinitrate
Store in a well closed container at a temperature below 25 degree C. Protects from light
Effects of Missed Dosage of Glyceryl Trinitrate
Take the missed dose as soon as noticed and if it is the time for next dose then skip the missed dose. Continue the regular schedule. Do not double the dose.
Effects of Overdose of Glyceryl Trinitrate
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 Glyceryl Trinitrate 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 glyceryl trinitrate and other medicines and health products. Home delivery services for glyceryl trinitrate 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 glyceryl trinitrate 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 glyceryl trinitrate before they complete the sale. You can get this information while placing the order for glyceryl trinitrate with the pharmacy.

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