GI/Poisoning: N-ACETYLCYSTEINE

Question 1

N-ACETYLCYSTEINE: INDICATIONS

Answer 1

• Paracetamol poisoning
• Prevent renal injury due to radiographic contrast material (contrast nephropathy)
• Reduce viscosity of respiratory secretions (acting as a mucolytic)

Question 2

N-ACETYLCYSTEINE: MOA

Answer 2

• Acetaminophen -> Conjugated to GLUCURONIDE + SULFATE (non toxic moieties)
• Acetaminophen also converted to NAPQI (via p450 enzymes) which is hepatotoxic, however this is quickly cleared by GLUTATHIONE
• In paracetamol poisoning, G supply is overwhelmed so NAPQI builds up
• NA works by replenishing the body’s G supply
• Also antioxidant effects = prevents contrast nephropathy
• AC bought into contact with mucous = liqueification (bronchiectasis patients, aid SPUTUM CLEARANCE)

Question 3

N-ACETYLCYSTEINE: ADVERSE EFFECTS

Answer 3

• Anaphylactoid Rxn (when given in large doses)
• Similar to anaphylactic rxn (nausea, tachycardia, rash and wheeze) but involves histamine release independent of IgE abs
• Once rxn has settled (by stopping A and giving an ANTIHISTAMINE + BRONCHODILATOR) safe to restart A @ a lower rate of infusion
• Administered in a nebulised form as mucolytic, A may cause BRONCHOSPASM
• Bronchodilator should be given immediately afterward

Question 4

N-ACETYLCYSTEINE: WARNINGS

Answer 4

• Hx of an ANAPHYLACTOID RXN, does not CI its future use

- Must not be labelled as ALLERGIC -> lead to effective tx of paracetamol poisoning to be denied

Question 5

N-ACETYLCYSTEINE: INTERACTIONS

Answer 5

None

Question 6

N-ACETYLCYSTEINE: Example

Answer 6

ACETYLCYSTEINE