Isosorbide Mononitrate
Brand Name: Imdur
Generic Available
Common Dosage Forms:
Tablets, extended-release: 30 mg, 60 mg, 120 mg
*Isosorbide is also available as the dinitrate salt
FDA Indications/Dosages:
For the prophylactic treatment of angina pectoris due to coronary artery disease: Normal daily dose is 30-120 mg once daily in the morning. The starting dose is 30-60 mg given once daily in the morning. After several days the dose may be increased to 120 mg given as a single daily dose in the morning. Maximum daily dose is 240 mg. Tablets may be halved but they should not be crushed or chewed. Each dose should be followed by 4 ounces of fluid. The onset of action of isosorbide mononitrate is not sufficiently rapid enough to be useful in aborting acute anginal attacks.
Pharmacology/Pharmacokinetics: Isosorbide acts by reduction of myocardial oxygen demand through the relaxation of vascular smooth muscle. This relaxation causes dilation of peripheral arteries and veins which results in a reduction of left ventricular back pressure and more efficient blood flow within the myocardium. Terminal elimination half-life is between 6-7 hours. Tmax is 3-4 hours. Metabolism occurs via d-nitration and glucuronidation in the liver with elimination primarily occurring in the urine.
Drug Interactions: Alcohol may increase hypotensive effects. Additive effects may occur with other vasodilators, especially calcium-channel blockers.
Contraindications/Precautions: Contraindicated in patients who are hypersensitive to nitrates. Use is not recommended in patients during the acute phase of myocardial infarction or in those with congestive heart failure. Use with caution in patients with hypotension or volume depletion. Tolerance and physical dependence may occur after prolonged use. Pregnancy Category B.
Adverse Effects: The most common adverse effects are headache (~50%) and dizziness (~10%). Less common effects include rash, cutaneous vasodilation with flushing, nausea, vomiting, dry mouth, tinnitus, blurred vision, acne, or anxiety.
Patient Consultation:
May cause dizziness, headache, or flushing. Headaches are a sign of drug effectiveness. Do not adjust dosage to treat headache--use aspirin or acetaminophen as needed. Dizziness is more common when standing from a recumbent or seated position.
Swallow whole or halved, do not crush or chew.
Avoid alcohol while taking this medication.
Store in a cool, dry place away from sunlight and children.
If a dose is missed, take it as soon as possible. If it is closer to the time of your next dose than the dose you missed, skip the missed dose and return to your dosing schedule. Do not double doses.
Contact a physician if the above side effects are severe or persistent.
