Isosorbide Mononitrate information from DrugsUpdate
L - Caution when used during lactation
LI - Lab *
Isosorbide mononitrate is a drug used principally in the treatment of angina pectoris and acts by dilating the blood vessels so as to reduce the blood pressure. It is sold by AstraZeneca under the trade name Imdur, and marketed in the UK under the trade names: Monosorb, Chemydur. In india this drug is available under the brand names of Sorbitrate, Monotrate, Solotrate, and Monit.
Pharmacodynamics
Dosing regimens for most chronically used drugs are designed to provide plasma concentrations that are continuously greater than a minimally effective concentration. This strategy is inappropriate for organic nitrates. Several well-controlled clinical trials have used exercise testing to assess the antianginal efficacy of continuously delivered nitrates. In the large majority of these trials, active agents were indistinguishable from placebo after 24 hours (or less) of continuous therapy. Attempts to overcome tolerance by dose escalation, even to doses far in excess of those used acutely, have consistently failed. Only after nitrates have been absent from the body for several hours has their antianginal efficacy been restored. Isosorbide Mononitrate Extended-Release Tablets, during long-term use over 42 days dosed at 120 mg once daily, continued to improve exercise performance at 4 hours and at 12 hours after dosing but its effects (although better than placebo) are less than or at best equal to the effects of the first dose of
60 mg.
Pharmacokinetics
Isosorbide mononitrate relaxes vascular smooth muscles by stimulating cyclic-GMP. It decreases left ventricular pressure (preload) and arterial resistance (afterload).
Onset
20 min (oral as conventional tab).
Duration
8-10 hours (oral as conventional tab).
Absorption
Readily absorbed from the GIT (oral); peak plasma concentrations after 1 hour.
Distribution
Widely distributed: Smooth muscle cells of the blood vessels.
Metabolism
Converted to inactive metabolites including isosorbide and isosorbide glucuronide.
Excretion
Via urine (2% as unchanged); 4-5 hours (elimination half-life).
Isosorbide Mononitrate Indications / Isosorbide Mononitrate Uses
Information Not Available
Isosorbide Mononitrate Adverse Reactions / Isosorbide Mononitrate Side Effects
Hypotension, tachycardia, flushing, headache, dizziness, palpitation, syncope, confusion. Nausea, vomiting, abdominal pain. Restlessness, weakness and vertigo. Dry mouth, chest pain, back pain, oedema, fatigue, abdominal pain, constipation, diarrhoea, dyspepsia and flatulence.
Potentially Fatal: Severe hypotension and cardiac failure.
Precautions
Severe hypotension, particularly with upright posture, may occur with even small doses of Isosorbide Mononitrate. This drug should, therefore, be used with caution in patients who may be volume depleted or who, for whatever reason, are already hypotensive. Hypotension induced by Isosorbide Mononitrate may be accompanied by paradoxical bradycardia and increased angina pectoris.
Nitrate therapy may aggravate the angina caused by hypertrophic cardiomyopathy.
In industrial workers who have had long-term exposure to unknown (presumably high) doses of organic nitrates, tolerance clearly occurs. Chest pain, acute myocardial infarction, and even sudden death have occurred during temporary withdrawal of nitrates from these workers, demonstrating the existence of true physical dependence. The importance of these observations to the routine, clinical use of oral Isosorbide Mononitrate is not known.
Special Precautions
Severe renal or severe hepatic impairment, hypothyroidism, malnutrition, or hypothermia. Caution in patients who are already hypotensive. May aggravate angina caused by hypertrophic cardiomyopathy. Tolerance may develop after long-term treatment. Lactation.
Other Drug Interactions
Hypotensive effects may be increased when used with alcohol or vasodilators. Concurrent use with calcium channel blockers may lead to marked orthostatic hypotension.
Potentially Fatal: Significant hypotension may occur when used with phosphodiesterase-5 inhibitors.
Other Interactions
Information Not Available
Dosage
Oral
Management of angina, Heart failure
Adult: 20 mg 2-3 times daily. Dose may range from 20-120 mg daily.
Elderly: Intiate at lower doses.
Food(before/after)
Should be taken on an empty stomach (i.e. At least one hour before food or two hours after food).
List of Contraindications
Isosorbide Mononitrate and Pregnancy
Category C , Category B ( Monoket and extended release).
Isosorbide Mononitrate and Lactation
Caution when used during lactation
Isosorbide Mononitrate and Children
Safety and efficacy not established
Isosorbide Mononitrate and Geriatic
Dose selection should be cautious, usually starting at the lower end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and comorbidity.
Isosorbide Mononitrate and Other Contraindications
Severe hypotension or anaemia, hypovolaemia, heart failure due to obstruction, or raised intracranial pressure due to head trauma or cerebral haemorrhage.
Storage
Oral
Store at 20-25°C.
Lab interference
Oral
Store at 20-25°C.
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