A child was diagnosed with cystic fibrosis and was prescribed an inhaled agent to dissolve mucus plugging the airways. This agent is also used as an antidote to reverse the toxicity of wof drugs?
Correct Answer: Acetaminophen
Description: Acute paracetamol poisoning :- occurs especially in small children who have low hepatic glucoronide conjugating ability and also with over dosage. Clinical Manifestations:- nausea, vomi ting, abdominal pain and liver tenderness with no impairment of consciousness. After 12-18 hours centrilobular hepatic necrosis occurs which may be accompanied by renal tubular necrosis and hypoglycaemia that may progress to coma.Jaundice stas after 2 days. Fuher course depends on the dose taken. Fulminating hepatic failure and death are likely if the plasma levels are above the line joining 200 ug/ml at 4 hours and 30 ug/ml at 15 hours. If the levels are lower recovery with suppoive treatment is the rule. Mech of toxicity:- N acetyl- p-benzoquinoneimine (NAPQI) is a minor metabolite of paracetamol which is detoxified by conjugation with glutathione. When a very large dose of paracetamol is taken, glucuronidation capacity is saturated, more of the minor metabolite is formed--hepatic glutathione is depleted and this metabolite binds covalently to proteins in liver cells (and renal tubules) causing necrosis. In chronic alcoholics even 5-6 g taken in one day can result in hepatotoxicity because alcoholism induces CYP2E1 that metabolises paracetamol to NAPQI. Paracetamol is not recommended in premature infants (< 2 kg) for fear of hepatotoxicity. Treatment:- If the patient is brought early, vomiting should be induced or gastric lavage done. Activated charcoal is given orally or through the tube to prevent fuher absorption. specific antidote:- N-acetylcysteine(MUCOMIX, ANTIFEN) infused over i.v for 15 mins..Acetylcysteine It opens disulfide bonds in mucoproteins present in sputum--makes it less viscid, but has to be administered directly into the respiratory tract.(used in cystic fibrosis) mech of action of antidote:-It replenishes glutathione stores of liver and prevents binding of the toxic metabolite to other cellular constituents. Ref:- kd tripathi; pg num:- 206,207,219
Category:
Pharmacology
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