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ASPIRIN & OTHER SALICYLATES - Coggle Diagram
ASPIRIN & OTHER SALICYLATES
Salicylates include:
• Aspirin (acetyl salicylate)
• Magnesium choline salicylate
• Salicyl salicylate
• Sodium salicylate
properties
• Aspirin is unique among the NSAIDs in irreversibly acetylating (and thus inactivating) cyclooxygenase.
•
The other salicylates, and all other NSAIDs are reversible inhibitors of cyclooxygenase.
Aspirin is rapidly deacetylated by esterases in the body, producing salicylate.
• Some of the pharmacologic effects of aspirin are due to its salicylate metabolite.
actions
respiratory
• Salicylates uncouple oxidative phosphorylation which leads to elevated CO2 and increased respiration.
• Higher doses stimulate the respiratory center resulting in hyperventilation.
• At toxic levels central respiratory paralysis occurs.
platelets
• TXA2 induces platelet aggregation.
• Aspirin irreversibly inhibits TXA2 production in platelets.
• Platelets lack nuclei: they can't synthesize new enzyme, and the lack of TXA2 persists for the lifetime of the platelet.
• Low-dose aspirin selectively inhibits COX-1, therefore endothelial cell production of PGI2 by COX-2 is relatively unaffected.
• The decrease in TXA2 levels results in prolonged bleeding time
Uses
ANTI-INFLAMMATORY, ANTIPYRETIC AND ANALGESIC USES
• Treatmentofmildtomoderatepain.
• Effective analgesic for rheumatoid arthritis and other inflammatory joint conditions.
• Potentantipyretic.
CV uses
• Low doses are used for their cardioprotective effects.
Aspirin inhibits platelet aggregation.
contraindications
• Aspirin is avoided in children due to its potential association with Reye syndrome.
• However, high doses of aspirin are used to treat children during the acute phase of Kawasaki disease.
dosage
• Salicylates are analgesic and antipyretic at low doses.
• They are anti-inflammatory at higher doses.
• Low doses of aspirin (<100 mg daily) are used for their cardioprotective effects.
metabolism
• Aspirin is hydrolyzed to salicylate and acetic acid by esterases in tissues and blood.
• At low doses salicylate is converted by the liver into hydrosoluble conjugates that are rapidly excreted by the kidney.
• Elimination follows first-order kinetics with a half- life of about 3.5 hours.
With doses of aspirin of 1g or more, the conjugation enzymes become saturated and zero-order kinetics are observed.
The time required to eliminate 50% of the salicylate lengthens as the dose of aspirin increases.c
AE
• Epigastric distress
• Reye’s syndrome
• NERD
• Prolonged bleeding time
ANTI-URICOSURIC EFFECTS
• Low doses of aspirin compete with uric acid for secretion and thus reduce uric acid secretio
HEPATIC EFFECTS
• Salicylates can cause hepatic injury in patients treated with high doses of salicylates.
intoxication
Salicylism
• Mild chronic salicylate intoxication is called salicylism.
• The syndrome includes headache, dizziness, tinnitus, mental confusion and hyperventilation.
After an acute salicylate overdose patients typically present to the hospital with a mixed respiratory alkalosis and metabolic acidosis.
• Prolonged exposure to high doses of salicylates leads to depression of the medulla, with central respiratory depression and circulatory collapse.
• Respiratory failure is the usual cause of death.
ACETAMINOPHEN
Analgesic and antipyretic drug.
Technically it is not a NSAID.
• No anti-inflammatory or antiplatelet effects.
USES:
• Useful in mild to moderate pain.
• DOC for pain relief in osteoarthritis.
• DOC for children with fever and flulike symptoms.
• DOC for short-term treatment of fever and minor pain during pregnancy.
• Inadequate for inflammatory conditions such as rheumatoid arthritis.
• May be used as adjunct to antiinflammatory therapy.
AE
In therapeutic doses, acetaminophen has negligible toxicity in most individuals.
• When taken in overdose the drug is a hepatotoxin.
• Prompt administration of acetylcysteine, a sulfhydryl donor, may be lifesaving after an overdose.