Acetaminophen feb 24 2022 Flashcards
What is Acetaminophen also known as?
Tylenol
It is a popular medication that can be obtained over the counter (OTC).
What are the three classifications of Acetaminophen?
- Selective COX Inhibitor
- Antipyretic
- Analgesic
What does COX stand for?
Cyclooxygenase
What is the role of Cyclooxygenase?
Converts arachidonic acid into prostanoids: prostaglandins and related compounds such as thromboxane A2
How many types of COX are there?
Two types
Which type of COX does Acetaminophen primarily work on?
COX2
What does COX catalyze at sites of tissue injury?
The synthesis of prostaglandin E2 and prostaglandin I2
What are the effects of inhibiting COX2?
- Suppression of inflammation
- Alleviation of pain
- Reduction of fever
What is the mechanism of action of Acetaminophen?
Decreases prostaglandin synthesis in the CNS, reducing fever and pain
Where is Acetaminophen metabolized?
In the liver
What is the half-life of Acetaminophen?
Approximately two hours
What are the two pathways through which Acetaminophen is metabolized?
- Major pathway - produces nontoxic metabolites
- Minor pathway - produces a highly toxic metabolite
What is the highly toxic metabolite produced by the minor pathway?
N-acetyl-p-benzoquinoneimine
What happens during an Acetaminophen overdose?
A larger than normal amount is processed via the minor pathway, leading to liver damage
What are the indications for administering Acetaminophen?
To treat patients presenting with a fever over 38 degrees Celsius
What are the contraindications for Acetaminophen?
- Hypersensitivity
- Active Liver disease / hepatic impairment
What is the adult dose of Acetaminophen?
975 mg PO
What should you do if a patient has received less than 975 mg of Acetaminophen within 4 hours?
Administer the remaining amount to equal 975 mg
What is the pediatric dose of Acetaminophen?
15 mg/kg PO
What should be documented prior to administering Acetaminophen?
The patient’s temperature
What symptoms may indicate Acetaminophen toxicity?
- Nausea/Vomiting
- Diarrhea
- Diaphoresis
- Abdominal pain
What is the treatment for Acetaminophen overdose?
Acetylcysteine (Mucomyst ®)
How does Acetylcysteine work in the case of an overdose?
It reduces injury to the liver by substituting for depleted glutathione
When is Acetylcysteine nearly 100% effective at preventing severe liver injury?
If given within 8-10 hours of ingestion
True or False: There is still significant protection if Acetylcysteine is given 24 hours after poisoning.
True
