Isosorbide Mononitrate

Isosorbide mononitrate is the major active metabolite of isosorbide dinitrate (ISDN), and most of the clinical activity of the dinitrate is attributable to the mononitrate. The principal pharmacological action is relaxation of vascular smooth muscle and consequent dilatation of peripheral arteries and veins, especially the latter. Dilation of the veins promotes peripheral pooling of blood and decreases venous return to the heart (reducing preload). Arteriolar relaxation reduces systemic vascular resistance (reducing afterload).

• Prevention and treatment of angina pectoris due to coronary artery disease

Adult Dose (Oral):

• Tablet: 20 mg 2 times daily (morning and 7 hours apart); maintenance: 20-120 mg daily (1-6 tablets)
• Sustained Release Capsule: 50 mg once daily
• Elderly: Initiate at lower doses

Child Dose: Safety and efficacy not established

Common Side Effects:

• Headache
• Dizziness
• Increased heart rate
• Flushing (sense of warmth in the face, ears, neck and trunk)
• Orthostatic hypotension (sudden lowering of blood pressure on standing)
• Hypotension

Precautions:

• Isosorbide Mononitrate may decrease alertness, affect vision or make you feel sleepy and dizzy; do not drive if symptoms occur
• Avoid alcohol (may increase dizziness)
• Headaches usually go away after a few days; inform doctor if persists
• May develop tolerance over time; follow prescribed dosing schedule
• Do not take erectile dysfunction medications (sildenafil, tadalafil) as they may cause low blood pressure
• Severe hypotension, particularly with upright posture, may occur with even small doses

Contraindications:

• Severe hypotension or anaemia
• Hypovolaemia
• Heart failure due to obstruction
• Raised intracranial pressure due to head trauma or cerebral haemorrhage
• Allergy to isosorbide mononitrate

Drug Interactions:

• Concomitant use with phosphodiesterase inhibitors is contraindicated
• Concomitant use with riociguat is contraindicated (hypotension)
• Additive vasodilating effects with alcohol or other vasodilators
• Marked orthostatic hypotension with calcium channel blockers

Food Interactions: Consuming alcohol while taking Isosorbide Mononitrate may cause flushing, increased heart beat, nausea, thirst, chest pain and low blood pressure (Disulfiram reaction).

Use in Pregnancy: Category B; animal studies show no evidence of fetal harm; no adequate human studies; use only if clearly needed.

Use in Lactation: It is not known whether isosorbide mononitrate is excreted in human milk; caution should be exercised.

Renal Impairment: Safe in kidney disease; no dose adjustment recommended; however inform doctor if you have underlying kidney disease.

Hepatic Impairment: Probably safe in liver disease; dose adjustment may not be needed; consult your doctor.

Overdose: Severe hypotension, dizziness, headache, flushing, nausea, diarrhea; symptomatic treatment; gastric lavage; for hypotension, place patient in supine position and give IV fluids.