Other Names

Enteric Coated ASA, Asaphen, Aspirin, Novasen, Entrophen

Classification

Non-Steroidal Anti-Inflammatory; Analgesic; Antipyretic; Anticoagulant

Action

•ASA is a weak acid, which is easily and rapidly transformed for absorption in the stomach.

•It is hydrolyzed into salicylate, a highly protein bound drug, which is easily transformed for excretion in the liver

•Analgesic/Anti-inflammatory effects: Inactivates cyclo-oxygenase enzyme, which decreases the production of Prostaglandins (PG) in the tissue, blocking the pain receptors’ sensitivity and decreases inflammation

•Antipyretic effects: By inhibiting the release of PG, blood flow is enhanced to the vessels of the skin. This allows for easier release of heat through evaporation and convection. Though heat is easily released, heat production is not reduced by ASA

•Anti-coagulant effects: ASA inhibits Thromboxane A2 production, which is responsible for platelet aggregation. With the decrease in platelet aggregation the blood does not form clots as easily. The changes to the blood cell from ASA are irreversible, though the cell only lives from 5 to 7 days.

Other information: At high doses there is a direct stimulation of the respiratory center in the medulla, which increases rate and depth of respirations (hyperventilation).

• You may also find an increase of respiratory alkalosis from the hyperventilation as O2 consumption and CO2 production increase. At high doses ASA will block the secretion and re-absorption of uric acid

indications

•Mild to moderate pain relief

•Relief of fever

•Relief of inflammation

•To minimize reoccurrence of TIA or CVA caused by embolus or thrombus

•Prophylaxis against myocardial infarction, and combined use for thrombolytic care of MI

Contraindications

•Hypersensitivity to the medication

Precautions

•History of gastrointestinal ulcers/active peptic ulcer (active peptic ulcer should only be a relative contraindication to a single dose of ASA for prevention/treatment of acute coronary syndrome)

•Alcohol consumption

•Decreased renal function

•Anemia

•Vitamin K deficiency

•Administration during last trimester of pregnancy should be avoided as it may inhibit clotting factors of mother and unborn child and prolong the pregnancy or labour

•Administration during last trimester of pregnancy should be avoided as it may inhibit clotting factors of mother and unborn child and prolong the pregnancy or labour

•Discontinue use 5 - 7 days prior to surgery

Asthmatics may have hypersensitivity to ASA, caution should be taken with first time use, a good history prior to administration is essential.

Adverse Reactions

GI: Heartburn, nausea and vomiting, diarrhea at high doses

RENAL: Necrosis of renal papillary with long term use

OTHER: Dehydration, hyperglycemia or hypoglycemia, Reye’s syndrome (a CNS infection relative to viral infection in children such as chicken pox or influenza)

Interactions/Compatibility/Stability

•Anticoagulants (potentiating effects)

•Methotrexate (antimetabolite)

•Chlorpropamide (may increase hypoglycemic response)

Special Considerations

•Route: PO (chew and swallow)

•500 mg/kg is fatal

•Antidote: Induce vomiting and administer activated charcoal

Dosages

•Preparation: Tablets of variable strength (80 mg, 160 mg, 325 mg)

•Adult: 160 mg (tx of MI)

•Children: 10 - 15 mg/kg to a maximum of 65 mg/kg/day

•Precaution should be used when administering to children

Kinetics

Onset:        < 5 minutes

Peak:          2 hours (6 - 8 hours with Enteric Coated)

Duration:     Dose dependent

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