Isosorbide mononitrate is a long-acting organic nitrate used primarily for the prophylaxis and treatment of angina pectoris. It is the active metabolite of isosorbide dinitrate. The 60mg strength is typically formulated as an extended-release (ER/SR) tablet designed for once-daily administration, providing sustained anti-anginal effect and reducing the risk of nitrate tolerance.
Adult: For prophylaxis of angina: Extended-release 60mg tablet once daily, typically in the morning. Dose may be initiated at 30mg once daily and titrated to 60mg based on response and tolerability. Maximum recommended dose is 120mg once daily.
Note: Swallow the extended-release tablet whole with a glass of water, do not crush, chew, or split. Take on an empty stomach, at least 1 hour before or 2 hours after food to minimize variability in absorption. To avoid tolerance, ensure a daily nitrate-low interval of 10-14 hours. The once-daily dose is usually taken in the morning upon waking.
Isosorbide mononitrate is a prodrug that releases nitric oxide (NO) within vascular smooth muscle cells. NO activates soluble guanylyl cyclase, increasing intracellular cyclic guanosine monophosphate (cGMP). Elevated cGMP leads to dephosphorylation of myosin light chains, resulting in smooth muscle relaxation, vasodilation, and reduced myocardial oxygen demand.
Pregnancy: Category C: Animal studies show adverse effects. Use only if potential benefit justifies potential risk to the fetus. May cause maternal hypotension, reducing placental perfusion.
Driving: May cause dizziness, lightheadedness, or syncope. Patients should not drive or operate machinery until they know how the drug affects them, especially during initial therapy or dose escalation.
| Phosphodiesterase-5 Inhibitors (Sildenafil, Tadalafil, Vardenafil) | Profound, life-threatening hypotension | Contraindicated |
| Other Vasodilators (e.g., ACE inhibitors, ARBs, Calcium channel blockers, Alpha-blockers) | Additive hypotensive effect | Major |
| Alcohol | Enhanced vasodilation and hypotension | Major |
| Heparin | Possible reduced anticoagulant effect of heparin | Moderate |
| Dihydroergotamine | May reduce the anti-anginal effect of nitrates and increase ergot toxicity | Moderate |
| Antihypertensives | Potentiated hypotension | Moderate |
| Tricyclic Antidepressants (TCAs) | Hypotensive effects may be potentiated | Moderate |
Same composition (Isosorbide Mononitrate (60mg)), different brands: