What is the recommended regular dose of aspirin, atorvastatin (Lipitor), clopidogrel (Plavix), and sorbitrate (isosorbide dinitrate) for a patient with evolved myocardial infarction (MI)?

Recommended Dosing for Post-MI Pharmacotherapy

For a patient with evolved (established) myocardial infarction, prescribe aspirin 75-100 mg daily, atorvastatin 20-80 mg daily (targeting LDL-C <70 mg/dL), clopidogrel 75 mg daily (if within 12 months of MI or if aspirin-intolerant), and isosorbide dinitrate 10-40 mg three times daily as needed for anginal symptoms. 1, 2, 3

Aspirin Dosing Algorithm

Initial Phase (First Month Post-MI):

• Start with aspirin 150-325 mg daily during the acute phase 2, 4
• The American Heart Association recommends 150 mg daily for the first month with Grade A evidence 2
• After bare metal stent placement, use 325 mg daily for at least 1 month; after drug-eluting stent, continue for 3-6 months 1

Long-Term Maintenance (After First Month):

• Reduce to 75-100 mg daily and continue indefinitely 1, 2, 3
• This lower dose provides equivalent efficacy with significantly reduced bleeding risk compared to higher doses 4, 5
• The 162 mg dose shows similar mortality outcomes to 325 mg but with 14% increased bleeding risk (adjusted OR 1.14,95% CI 1.05-1.24) 4

Clopidogrel Dosing

Dual Antiplatelet Therapy Period:

• Load with 300-600 mg (if age <75 years), then 75 mg daily 1
• Continue for minimum 12 months post-MI in combination with aspirin 1
• After stenting: minimum 1 month for bare metal stents, 3-6 months for drug-eluting stents, ideally up to 12 months 1

Long-Term Monotherapy (After DAPT Period):

• Clopidogrel 75 mg daily is equivalent to aspirin as monotherapy for patients beyond the initial dual antiplatelet period 1, 3
• Use as first-line alternative if aspirin intolerance or allergy exists 1, 3
• Consider preferentially in patients with history of stroke/TIA or peripheral arterial disease 3

Atorvastatin Dosing

Initiate high-intensity statin therapy immediately:

• Start atorvastatin 20-40 mg daily as early as possible, titrate to 40-80 mg daily 2
• Target LDL-C <70 mg/dL (<1.8 mmol/L) or ≥50% reduction from baseline 2
• The European Society of Cardiology recommends starting during hospitalization with Class I, Level A evidence 2
• Continue indefinitely as part of secondary prevention 2

Isosorbide Dinitrate (Sorbitrate) Dosing

For symptomatic angina management:

• Standard dosing: 10-40 mg three times daily (or 5-20 mg two to three times daily) with a nitrate-free interval of 10-14 hours to prevent tolerance 1
• Use as second-line antianginal therapy if symptoms persist despite beta-blockers and/or calcium channel blockers 1
• Long-acting nitrates should be considered as add-on therapy for inadequate symptom control, not as monotherapy 1

Critical Clinical Pitfalls

Bleeding Risk Management:

• Patients on triple therapy (aspirin + clopidogrel + anticoagulation) have significantly increased bleeding risk 1
• Consider adding proton pump inhibitor for gastrointestinal protection in high-risk patients 2, 3
• Monitor closely for bleeding complications, especially gastrointestinal 2

Drug Interactions:

• Avoid NSAIDs, particularly ibuprofen, which blocks aspirin's antiplatelet effects 3
• Proton pump inhibitors may interfere with clopidogrel metabolism, though clinical significance remains debated 1
• Clopidogrel requires hepatic conversion to active metabolite; genetic polymorphisms may affect response 3

Premature Discontinuation:

• Never stop dual antiplatelet therapy prematurely in stented patients—this dramatically increases stent thrombosis risk 1
• If surgery is required, coordinate with cardiology; clopidogrel should be held 5-7 days before elective procedures 1

Nitrate Tolerance:

• Ensure nitrate-free interval of 10-14 hours daily to maintain efficacy 1
• Do not use nitrates with phosphodiesterase-5 inhibitors (sildenafil, tadalafil) due to severe hypotension risk