A fixed-dose combination (FDC) of a long-acting organic nitrate vasodilator (Isosorbide Mononitrate) and a low-dose antiplatelet agent (Aspirin). Primarily used for the secondary prevention of angina pectoris in patients with established coronary artery disease (CAD). The combination aims to reduce myocardial oxygen demand through preload reduction and prevent thrombotic events through platelet inhibition, offering a convenient dosing regimen to improve adherence in the Indian context where polypharmacy is common.
Adult: One tablet (Isosorbide Mononitrate 60mg SR + Aspirin 75mg) orally once daily, typically in the morning. For angina prophylaxis, the nitrate component requires a daily nitrate-free interval; thus, morning dosing is standard.
Note: Swallow the tablet whole with a full glass of water, with or without food (preferably with food to minimize GI upset from aspirin). Do not crush, chew, or break the sustained-release tablet. Take in the morning upon waking. If a dose is missed, take it as soon as remembered unless it is almost time for the next dose. Do not double the dose.
The combination works via two complementary pathways: 1) Isosorbide Mononitrate is converted to nitric oxide (NO), which activates guanylyl cyclase, increasing cGMP, leading to venous and arterial vasodilation (venous predominance). This reduces preload and afterload, decreasing myocardial oxygen demand. 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 the 3rd trimester. Aspirin may cause premature closure of ductus arteriosus, increased risk of neonatal bleeding, and prolonged labor. Use only if potential benefit justifies the fetal risk, typically not for angina prophylaxis.
Driving: May cause dizziness, lightheadedness, or syncope, especially when initiating therapy or after alcohol consumption. Patients should not drive or operate machinery until they know how the medication affects them.
| Phosphodiesterase-5 Inhibitors (Sildenafil, Tadalafil, Vardenafil) | Profound, life-threatening hypotension due to synergistic vasodilation. | Contraindicated |
| Other Anticoagulants/Antiplatelets (Warfarin, Clopidogrel, NOACs) | Increased risk of bleeding, including GI and intracranial hemorrhage. | Major |
| NSAIDs (Ibuprofen, Diclofenac, Naproxen) | Competitive COX-1 inhibition may reduce aspirin's cardioprotective effect; increased GI toxicity. | Major |
| ACE Inhibitors/ARBs (Ramipril, Losartan) | Additive hypotensive effect. | Moderate |
| Beta-blockers (Metoprolol, Atenolol) | May potentiate hypotension; also useful combination for angina. Monitor BP. | Moderate |
| Calcium Channel Blockers (Amlodipine, Diltiazem) | Additive vasodilation and hypotensive effect. | Moderate |
| Alcohol | Increased risk of GI bleeding and potentiation of vasodilation/hypotension. | Moderate |
| Methotrexate | Aspirin decreases renal clearance of methotrexate, increasing toxicity risk. | Major |
| Sulfonylureas (Glibenclamide) | Aspirin may potentiate hypoglycemic effect. | Moderate |
| Corticosteroids (Prednisolone) | Increased risk of GI ulceration and bleeding. | Major |
| Antacids | May alter absorption of aspirin (urinary alkalinizers increase salicylate excretion). | Minor |
Same composition (Isosorbide Mononitrate (60mg) + Aspirin (75mg)), different brands: