**Question:** Hemoperfusion with charcoal is useful in poisoning with

A. carbon monoxide
B. methotrexate
C. digoxin
D. acetaminophen

**Core Concept:** Hemoperfusion is a dialysis technique that involves passing blood through an extracorporeal device, where toxins are removed from the blood. Charcoal is a common adsorbent used in hemoperfusion due to its high surface area, which allows it to bind various toxins.

**Why the Correct Answer is Right:** Hemoperfusion with charcoal is particularly useful in poisoning with carbon monoxide (A) because it binds and removes carbon monoxide from the bloodstream. Carbon monoxide is a highly toxic gas that forms when hemoglobin binds to carbon monoxide, leading to impaired oxygen delivery and cellular damage. Hemoperfusion with charcoal can effectively remove carbon monoxide and alleviate its toxic effects.

**Why Each Wrong Option is Incorrect:**

B. Methotrexate (option B) is an antifolate drug used for chemotherapy. While methotrexate can cause severe toxicity, it is primarily removed from the blood by renal clearance and protein binding, not hemoperfusion with charcoal.

C. Digoxin (option C) is a cardiac glycoside used for heart failure treatment. Hemoperfusion with charcoal can remove digoxin to some extent, but its primary excretion routes are renal clearance and biliary excretion.

D. Acetaminophen (option D) is an analgesic and antipyretic drug, often used for pain management. Hemoperfusion with charcoal can bind and remove acetaminophen from the blood, making it a suitable treatment option for acetaminophen poisoning.

**Clinical Pearl:** In poisoning cases, it is essential to consider the specific toxin involved when deciding on the appropriate treatment modality. Hemoperfusion with charcoal primarily targets certain toxins like carbon monoxide and acetaminophen, while relying on alternative routes of elimination for other toxins (e.g., renal clearance, biliary excretion). A thorough understanding of the pharmacokinetics and pharmacodynamics of drugs and toxins is crucial for selecting the most effective treatment strategy.