Aspirin

# Aspirin ## Overview - **Classification**: Salicylate, Non-Steroidal Anti-Inflammatory Drug (NSAID), Antiplatelet. - **Mechanism**: Irreversibly inhibits cyclooxygenase (COX-1 and COX-2) enzymes, preventing prostaglandin synthesis (anti-inflammatory, analgesic, antipyretic) and thromboxane A2 formation (antiplatelet). ## Primary Indications 1. **Cardiovascular Event Prevention**: Secondary prevention of MI, stroke, and other thrombotic events. 2. **Acute Coronary Syndromes (ACS)**: Immediate treatment in suspected MI or unstable angina. 3. **Pain & Fever**: Mild to moderate pain relief and fever reduction. 4. **Inflammatory Conditions**: Rheumatoid arthritis, osteoarthritis (higher doses). 5. **Kawasaki Disease**: Anti-inflammatory and antiplatelet in children (specific indications only). ## Adult Dosing ### Standard Dosing **Acute Coronary Syndromes (ACS) / Suspected MI** - **Dose**: **162-325 mg** - **Frequency**: Once (initial chewable dose) - **Route**: Oral (chewed for faster absorption) - **Duration**: Followed by maintenance dose. **Secondary Prevention of Cardiovascular Events / Stroke** - **Dose**: **81 mg** or **162 mg** - **Frequency**: Once daily - **Route**: Oral **Pain / Fever / Inflammation** - **Dose**: **325-650 mg** - **Frequency**: Every 4-6 hours as needed - **Route**: Oral - **Maximum**: **4 grams/day** ### Dose Adjustments - **Renal Impairment**: Use with caution. Avoid high doses in severe renal dysfunction (CrCl < **30 mL/min**) due to accumulation of active metabolites. - **Hepatic Impairment**: Use with caution. Increased risk of bleeding. Avoid in severe hepatic failure. - **Elderly Patients**: Use lowest effective dose. Increased risk of gastrointestinal (GI) bleeding and renal impairment. ## Pediatric Dosing ### Neonates (0-28 days) - **Dose**: Generally **not recommended** due to high risk of toxicity and lack of safety data. - **Special Notes**: Used rarely for highly specialized indications (e.g., specific cardiac shunts) under strict specialist guidance. ### Infants (1-12 months) - **Dose**: **ABSOLUTELY AVOID** for fever/pain/viral illness due to **Reye's Syndrome risk**. * **Kawasaki Disease (Acute Phase)**: **30-50 mg/kg/day** * **Frequency**: Divided every 6 hours * **Maximum**: **80 mg/kg/day** (or **4 grams/day**) * **Kawasaki Disease (Convalescent Phase)**: **3-5 mg/kg/day** * **Frequency**: Once daily * **Maximum**: **81 mg/day** - **Special Notes**: Only for specific conditions like Kawasaki disease under specialist supervision. ### Children (1-12 years) - **Dose**: **ABSOLUTELY AVOID** for fever/pain/viral illness due to **Reye's Syndrome risk**. * **Kawasaki Disease (Acute Phase)**: **30-50 mg/kg/day** * **Frequency**: Divided every 6 hours * **Maximum**: **80 mg/kg/day** (or **4 grams/day**) * **Kawasaki Disease (Convalescent Phase)**: **3-5 mg/kg/day** * **Frequency**: Once daily * **Maximum**: **81 mg/day** * **Rheumatic Fever/JIA**: **50-75 mg/kg/day** (initially, can increase to 100 mg/kg/day) * **Frequency**: Divided every 4-6 hours * **Maximum**: **4 grams/day** - **Special Notes**: Use strictly limited to specific inflammatory/antiplatelet indications (e.g., Kawasaki, rheumatic fever, JIA) under specialist guidance. ### Adolescents (13-18 years) - **Dose**: **ABSOLUTELY AVOID** for fever/pain/viral illness due to **Reye's Syndrome risk**. * For adult-like indications (e.g., cardiovascular prevention if no viral risk): Adult dosing applies. * **Antiplatelet**: **81 mg** orally **once daily** * **Pain/Fever**: **325-650 mg** orally **q4-6h** - **Maximum**: **4 grams/day** - **Special Notes**: Counsel patients and parents on **Reye's Syndrome risk** with viral infections. ## Safety Information ### Contraindications - **Absolute**: Allergy to NSAIDs or salicylates. - **Absolute**: Children/adolescents with viral infections (risk of Reye's Syndrome). - **Absolute**: GI bleeding, active peptic ulcer disease. - **Absolute**: Hemophilia or other bleeding disorders. - **Absolute**: Third trimester of pregnancy (risk of premature ductus arteriosus closure). - **Relative**: Asthma (aspirin-exacerbated respiratory disease), severe hepatic/renal impairment. ### Common Adverse Effects - **Very Common (>10%)**: Dyspepsia, nausea, heartburn. - **Common (1-10%)**: GI irritation, minor GI bleeding, tinnitus (high doses), rash. - **Serious but Rare**: Major GI bleeding, Reye's Syndrome, angioedema, anaphylaxis, acute renal failure. ### Key Drug Interactions - **Anticoagulants (e.g., Warfarin, DOACs)**: Increased risk of bleeding. Monitor INR/clinical signs. - **Other NSAIDs**: Increased risk of GI bleeding and ulceration. Avoid concurrent use. - **SSRIs/SNRIs**: Increased risk of GI bleeding. Caution advised. - **Corticosteroids**: Increased risk of GI ulceration and bleeding. - **Methotrexate**: May increase methotrexate levels and toxicity. Monitor for toxicity. - **Alcohol**: Increased risk of GI bleeding. Avoid excessive consumption. ## Monitoring & Follow-up - **Before Treatment**: Assess bleeding risk (history of ulcers, current anticoagulants). - **During Treatment**: Monitor for signs of GI bleeding (black stools, vomiting blood), tinnitus (toxicity), and hypersensitivity reactions. - **Clinical Signs**: Watch for unusual bruising, prolonged bleeding, severe abdominal pain, dark stools, or ringing in the ears. ## Clinical Pearls - 💡 **Acute MI**: For suspected MI, chew **162-325 mg** aspirin immediately for faster absorption. - 💡 **GI Protection**: Consider proton pump inhibitors (PPIs) in patients at high risk of GI bleeding on long-term aspirin. - 💡 **Reye's Syndrome**: **NEVER** use aspirin for fever or pain in children/adolescents with viral infections (e.g., flu, chickenpox). This is a critical safety warning. - 💡 **Compliance**: Emphasize importance of daily adherence for cardiovascular prevention, even if feeling well. - 💡 **Drug Holiday**: Avoid abrupt discontinuation of low-dose aspirin after coronary stenting due to risk of stent thrombosis. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.