Clinical beta

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Drug Monograph

Aspirin

USE IF: ACS (chewed), secondary prevention CVD, stroke/TIA prevention, pericarditis, Kawasaki, pre-eclampsia prevention

AVOID IF: Child with viral illness, active GI bleed, severe renal/hepatic failure, AERD, >=28 weeks pregnancy (analgesic doses)

Aspirin (acetylsalicylic acid)

Antiplatelet β€” irreversible COX-1 inhibitor

High YieldCADStrokeAdultPediatric caution

Indication

**Secondary prevention** where guideline-indicated β€’ **Primary prevention** only **selected** patients (not population-wide) Secondary CAD/stroke prevention β€’ ACS (loading + maintenance context) β€’ Kawasaki (specialist) β€’ preeclampsia prevention (OB protocol)

At a glance

INDICATION -> ACS: give 162–325 mg chewed immediately

ADULT DOSE -> Antiplatelet: 75–100 mg daily

MAX DOSE -> 3,900 mg/day OTC; up to 5,400–8,000 mg/day specialist

CONTRA -> Children viral illness, active bleed, AERD, severe renal failure

ANTIDOTE -> No specific; IV sodium bicarbonate + hemodialysis

Quick facts

Onset

15-30 min (chewed); 30-60 min (tablet).

Duration

Peak 1-2 h; analgesia 4-6 h; antiplatelet effect 7-10 days.

Routes

PO, PR, IV (lysinate).

Pregnancy

Low-dose acceptable for pre-eclampsia; avoid analgesic doses >=28 weeks.

Renal

Avoid high doses if eGFR <30.

Hepatic

Avoid severe impairment.

Do not miss

Time to action: 15-30 min (chewed); platelet effect irreversible 7-10 days

Max dose

  • 3,900 mg/day OTC; higher doses only with specialist supervision.

Critical risks

  • GI bleed, Reye's syndrome, salicylate toxicity, and AERD are critical risks.

Platelet effect duration

  • Irreversible platelet inhibition lasts 7-10 days.
  • Bleeding risk can persist even after stopping.

Reversal

  • No direct antidote.
  • Platelet transfusion required if severe bleeding.
  • ACID-BASE PATTERN: early respiratory alkalosis -> later metabolic acidosis.
  • Mixed disorder = classic salicylate toxicity clue.

Key interactions

  • Warfarin/NOACs, ibuprofen, methotrexate, SSRIs, and ACEi/ARB are key interactions.

Indications

Primary

  • ACS
  • Secondary prevention MI/stroke
  • Pain/fever

Secondary

  • Pericarditis
  • Pre-eclampsia prevention
  • Kawasaki disease
  • Acute rheumatic fever

Other

  • AF when no anticoagulation
  • APS (off-label)

Dosing

Standard: Antiplatelet (cardiovascular): 75-100 mg daily

Max daily dose

  • Antiplatelet standard: 75-100 mg daily.
  • Analgesic/anti-inflammatory: max up to 4 g/day (specialist).

Antiplatelet (cardiovascular)

  • NOTE: Always clarify indication before dosing.
  • ACS: 162–325 mg (chewed) immediately; then 75–100 mg daily.
  • Antiplatelet (secondary prevention): 75–100 mg daily.

Analgesic / anti-inflammatory

  • 300–600 mg q4–6h PRN.
  • Max up to 4 g/day (specialist).

Pediatric

  • Kawasaki: 80-100 mg/kg/day -> then low-dose phase.

Renal adjustment

  • eGFR >=30: low-dose acceptable.
  • eGFR <30: avoid high doses.

Hepatic adjustment

  • Mild disease: caution.
  • Severe disease: avoid.

Warnings

Clinical warnings

  • GI bleeding risk at any dose.
  • Reye's syndrome risk in children with viral illness.
  • Chronic toxicity in elderly can present as tinnitus or confusion.
  • AERD risk in susceptible asthmatics.
  • Perioperative bleeding risk (typically stop 5-7 days pre-op when appropriate).
  • Low-dose therapy can exacerbate gout.
  • AKI risk increases with ACEi/ARB combinations.

Adverse effects

  • Common: dyspepsia, nausea, bruising, dyspeptic pain.
  • Serious: GI bleed, salicylate toxicity, intracranial bleeding, hypersensitivity.

Contraindications / caution

Do not use

  • Active GI bleed.
  • AERD / aspirin allergy.
  • Children with viral illness.
  • Severe hepatic failure.
  • Pregnancy >=28 weeks for analgesic dosing.

Use caution / avoid high doses

  • Elderly
  • CKD
  • Anticoagulants
  • History of ulcers
  • Alcohol use

Drug interactions

  • Warfarin/NOACs -> increased major bleeding risk.
  • Ibuprofen -> can block aspirin antiplatelet cardioprotection.
  • Methotrexate -> increased toxicity.
  • SSRIs -> increased GI bleed risk.
  • ACEi/ARB -> reduced efficacy and increased AKI risk.

Special populations

Pediatrics

Avoid routine use; valid specialist indications include Kawasaki and ARF only.

Pregnancy

Low-dose aspirin (75-150 mg) is safe and commonly used for pre-eclampsia prevention; high-dose is contraindicated in 3rd trimester (premature ductus arteriosus closure); avoid analgesic dosing in late pregnancy.

Breastfeeding

Low-dose generally acceptable; avoid high-dose use.

Elderly

Do not start primary prevention >=60 years; monitor closely for toxicity.

Liver disease

Avoid severe liver disease.

Renal impairment

Avoid high doses if eGFR <30.

Administration

  • PO preferred; chew immediately in ACS for faster effect.

Infusion / dilution

  • IV: reconstitute 500 mg vial per protocol.
  • Bolus over >=30 seconds; infusion over 15-20 minutes.

Monitoring

  • Salicylate levels for high-dose or toxicity concern.
  • Renal function.
  • LFTs.
  • INR if on warfarin.
  • Clinical bleeding.
  • Tinnitus/confusion as early toxicity markers.
  • Blood pressure (NSAID effect).

Overdose / toxicity

IF SUSPECTED ASPIRIN OVERDOSE: β€’ Check salicylate level, ABG, electrolytes immediately β€’ Start urine alkalinization early (IV sodium bicarbonate) β€’ DO NOT intubate unless absolutely necessary (risk of rapid acidosis) β€’ Early toxicology consult. ESCALATE URGENTLY IF: β€’ Salicylate >100 mg/dL (acute) β€’ Severe acidosis (pH <7.2) β€’ Altered mental status β€’ Pulmonary edema β€’ Renal failure β†’ Consider hemodialysis early (EXTRIP)

Recognition

  • Toxic dose generally >150 mg/kg.
  • Early: tinnitus and hyperventilation.
  • Late/severe: metabolic acidosis, altered mental status, pulmonary edema.

Immediate actions

  • Always check salicylate level plus ABG early.
  • Activated charcoal early when appropriate.
  • IV fluids plus glucose support.
  • IV sodium bicarbonate (target serum pH 7.45-7.55 and urine pH >=7.5).
  • Correct potassium before alkalinization.

Antidote

  • No specific antidote.

Decontamination

  • Activated charcoal in early presentation if airway is protected.

Escalation

  • Hemodialysis for severe toxicity, level around 100 mg/dL, altered mental status, or acidosis.
  • Indications for hemodialysis:
  • Severe acidosis (pH <7.2).
  • Salicylate level >100 mg/dL (acute).
  • Altered mental status.
  • Pulmonary edema.
  • Renal failure.
  • Consider hemodialysis early (EXTRIP).

Clinical pearls

Common mistakes, resistance logic, and bedside traps

ACS

  • Chew aspirin in ACS for faster antiplatelet effect.

Platelets

  • Effect lasts the full platelet lifespan (about 7-10 days).

Ibuprofen timing

  • Ibuprofen can cancel aspirin cardioprotection if timed poorly.

Elderly toxicity

  • Toxicity in older adults may present subtly (tinnitus, confusion).

Overdose key

  • Bicarbonate is a cornerstone in salicylate overdose management.

Nomogram

  • Do not use the Done nomogram for salicylate toxicity decisions.

Primary prevention

  • Do not newly start primary prevention in adults >=60 years.

Pre-eclampsia

  • Start prophylaxis by <=16 weeks when indicated.

Pediatrics

  • Kawasaki disease is a rare valid pediatric aspirin indication.

ASPIRIN INTERACTION

  • Naproxen may reduce aspirin's antiplatelet effect.
  • Give aspirin >=30 min before OR >=8 hours after naproxen.
  • Avoid routine combination in high CV-risk patients unless necessary.

Pharmacokinetics

  • Rapid hydrolysis to salicylate.
  • Elimination becomes non-linear at high doses.
  • Renal excretion increases with alkaline urine.
  • Protein binding approximately 58-80%.

Mechanism of action

  • Irreversible COX-1 and COX-2 inhibition.
  • Reduced TXA2 synthesis decreases platelet aggregation for 7-10 days.
  • Reduced prostaglandins provide analgesic, antipyretic, and anti-inflammatory effects.

Common brand names

Saudi Arabia

Ecotrin Β· Bayer

Global

(placeholder β€” verify local product)

Common trade names are curated examples only β€” formulations and availability vary. Verify the exact product name with your local pharmacy and national regulator before prescribing or dispensing.

Country practice notes

  • DAPT duration and perioperative management follow **ESC/AHA/ACC** and local cardiology consensus β€” not one-size rules.
  • Primary prevention aspirin thresholds differ by guideline and age β€” verify regional primary-care policy.

Saudi Arabia β€” confirm with local formulary.