Acetylsalicylic Acid
Synonym :
Aspirin
Mechanism :
Aspirin (acetylsalicylic acid) an analgesic, antipyretic, and anti-inflammatory agent. Its mode of action is due to inhibition of synthesis and release of prostaglandins. Aspirin appears to produce analgesia by both a peripheral and a CNS effect. Peripherally, aspirin acts by inhibiting the synthesis and release of prostaglandins. Acting centrally, it produces analgesia at a hypothalamic site in the brain, although the mode of action is not known.
Indication :
- Pain and Fever
- Juvenile Rheumatoid arthritis
- Kawasaki disease
- Anti-platelet
- Rheumatic fever
Contraindications :
Bleeding disorders like hemophilia and others, active peptic ulcer, asthmatics, impaired renal or liver function and G6PD deficiency. Not recommended in children till the age of 15 years if feverish. It should be avoided in patients with dengue fever to prevent bleeding and in viral fevers for risk of precipitating Reye’s syndrome.
Dosing :
Anti-inflammatory, antipyretic, analgesic:
<12 years: 10-15 mg/kg orally every 4 hours; maximum of 60-80 mg/kg/day.
≥12 years: 325-650 mg orally/rectally every 4-6 hours, as when needed.
Kawasaki disease:
80-100 mg/kg/day orally, 4 times/day. After the fever resolves decrease dose to 3-6 mg/kg/day given orally in single dose as for maintenance.
Juvenile Rheumatoid Arthritis:
<25 kg: 60-100 mg/kg/day orally, every 6-8 hours (Maintain serum salicylate at 150-300 mcg/mL).
≥25 kg: 2.4-3.6 g/day.
Anti-platelet:
3-5 mg/kg/day OD, maximum 75 mg.
Rheumatic fever:
100 mg/kg/day divided into 4 to 5 doses; if response inadequate, may increase dose to 125 mg/kg/day; continue for 2 weeks; then decrease dose to 60 to 70 mg/kg/day in divided doses for an additional 3 to 6 weeks.
Adverse Effect :
Gastrointestinal irritation, gastric bleeding and ulceration, bronchospasm, interstitial nephritis, renal papillary necrosis, hepatotoxicity, hypoglycemia, pulmonary edema. High dose ingestion may cause salicylism characterised by tinnitus, respiratory acidosis and finally coma.
Interaction :
Anticoagulants: Increased risk of bleeding.
NSAIDS: Increased risk of side effects.
Methotrexate: Decreased excretion.
Phenytoin and sodium valproate: Enhanced effect.
ACE Inhibitors: Salicylates may diminish the antihypertensive effect of ACE Inhibitors.
Loop Diuretics: Salicylates may diminish the diuretic effect of Loop Diuretics. Loop Diuretics may increase the serum concentration of Salicylates.
Valproic Acid: Salicylates may increase the serum concentration of Valproic Acid.
Vaccines: Salicylates may enhance the adverse/toxic effect of Varicella Virus-Containing Vaccines and influenza vaccines. Reye's Syndrome may develop.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function. |
| 10-20 | Dose as in normal renal function. |
| <10 | Dose as in normal renal function. |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Dialysed. Dose as in normal renal function |
| HD | Dialysed. Dose as in normal renal function |
| HDF/High flux | Dialysed. Dose as in normal renal function |
| CAV/VVHD | Dialysed. Dose as in normal renal function |
Hepatic Dose :
Mild to moderate hepatic impairment: Liver function tests should be monitored. No dosage adjustments are recommended.
Severe hepatic impairment: Avoid use.