A fixed-dose combination (FDC) of a long-acting organic nitrate vasodilator (Isosorbide Mononitrate) and a low-dose antiplatelet agent (Acetylsalicylic Acid/Aspirin). Primarily used for the secondary prevention of cardiovascular events in patients with stable coronary artery disease (CAD), particularly for angina prophylaxis and reducing the risk of myocardial infarction (MI) and stroke. The combination addresses both the symptomatic relief of angina (via nitrate-induced vasodilation) and the underlying thrombotic risk (via aspirin's antiplatelet effect).
Adult: One tablet (Isosorbide Mononitrate 30mg + Aspirin 75mg) orally once daily, typically in the morning. The Isosorbide Mononitrate component is often a sustained-release formulation for once-daily dosing to provide a nitrate-free interval.
Note: Take with a full glass of water, with or after food to minimize gastric irritation from aspirin. Swallow the tablet whole; do not crush or chew. Take at the same time each day, preferably in the morning to coincide with peak angina risk and to allow a nitrate-free period. Do not use for acute angina attacks; sublingual nitrates should be used for that purpose.
The combination works via two distinct pathways: 1) Isosorbide Mononitrate is metabolized to release nitric oxide (NO), which activates guanylyl cyclase, increasing cGMP, leading to venous and arterial vasodilation. This reduces preload and afterload, decreasing myocardial oxygen demand and relieving angina. 2) Aspirin irreversibly acetylates platelet cyclooxygenase-1 (COX-1), inhibiting thromboxane A2 synthesis, a potent platelet aggregator and vasoconstrictor, thereby preventing arterial thrombosis.
Pregnancy: Category C (Nitrates) / Category D (Aspirin in 3rd trimester). Avoid, especially in third trimester. Aspirin may cause premature closure of ductus arteriosus, increased risk of bleeding in mother and neonate, and prolonged gestation/labor. Use only if potential benefit justifies fetal risk, under specialist supervision.
Driving: May cause dizziness, lightheadedness, or syncope, especially during initiation or dose escalation. Patients should not drive or operate machinery until they know how the medication affects them, particularly in the first few days of treatment.
| Other Antiplatelets/Anticoagulants (Clopidogrel, Warfarin, NOACs) | Potentiates antiplatelet/anticoagulant effect, significantly increasing risk of major bleeding. | Major |
| NSAIDs (Ibuprofen, Diclofenac) | Increases GI toxicity and bleeding risk; may antagonize aspirin's cardioprotective effect by competing for COX-1 binding. | Major |
| Phosphodiesterase-5 Inhibitors (Sildenafil, Tadalafil) | Profound hypotension due to synergistic vasodilation via cGMP pathway. | Contraindicated |
| Antihypertensives (Beta-blockers, ACE inhibitors, Diuretics) | Additive hypotensive effect. | Moderate |
| Alcohol | Increases risk of GI bleeding and potentiates vasodilation/hypotension. | Moderate |
| Methotrexate | Aspirin decreases renal clearance of methotrexate, increasing risk of toxicity. | Major |
| Sulfonylureas (Glibenclamide) | Aspirin may potentiate hypoglycemic effect. | Moderate |
| Corticosteroids (Prednisolone) | Increase risk of GI ulceration and bleeding. | Moderate |
| Probenecid | Aspirin may antagonize uricosuric effect. | Moderate |
Same composition (Isosorbide Mononitrate (30mg) + Aspirin (75mg)), different brands: