Which NSAID undergoes enterohepatic circulation?

KGMU 2024

Pharmacology

Easy

Appeared in: KGMU 2024

Explanation

Piroxicam is an enolic acid derivative (oxicam) NSAID known for its very long plasma half-life.
The primary reason for its long half-life (approximately 50-60 hours) is that it undergoes extensive enterohepatic circulation.
This process involves the drug being excreted in the bile, reabsorbed in the intestine, and returned to the liver, effectively recycling it within the body.
This pharmacokinetic property allows for the convenience of single daily dosing, which is particularly useful for managing chronic inflammatory diseases.

Option A: Phenylbutazone has a long half-life, but this is primarily due to its high degree of plasma protein binding, not significant enterohepatic circulation. Its use is also highly restricted due to severe toxicity, such as aplastic anemia.
Option B: Aspirin has a very short half-life of about 15-20 minutes because it is rapidly hydrolyzed in the plasma and liver. It does not undergo enterohepatic circulation.
Option C: Ibuprofen is a propionic acid derivative with a short half-life of about 2-4 hours. It requires multiple daily doses and does not undergo significant enterohepatic circulation.

Visual 1: Diagram - A flowchart illustrating the pathway of enterohepatic circulation, showing a drug moving from the liver to bile, to the intestine, and re-entering circulation via the portal vein. This helps visualize why the drug's effect is prolonged.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacokinetics of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) as background academic context rather than a clinical decision trigger.
Understanding a drug's half-life is critical for patient education on dosing schedules. For a drug like Piroxicam, the nurse must emphasize the importance of not taking more than the prescribed single daily dose, as its long half-life increases the risk of accumulation and toxicity.
The prolonged action and increased risk of GI side effects with drugs like Piroxicam mean nurses must be vigilant in assessing for signs of gastrointestinal bleeding (e.g., black, tarry stools; coffee-ground emesis) in patients on long-term therapy.
What if? If a patient with liver dysfunction is prescribed an NSAID that undergoes enterohepatic circulation, the risk of toxicity is significantly increased. The nurse's role would be to question the prescription, advocate for an alternative drug with a different metabolic pathway (e.g., one primarily cleared by the kidneys), and closely monitor liver function tests.

How to Approach the Question

First, identify the core concept of the question, which is 'enterohepatic circulation' in the context of 'NSAIDs'. This is a factual recall question from pharmacology.
Recall the pharmacokinetic properties of the major classes of NSAIDs provided in the options.
Consider the half-life of each drug. A very long half-life is often a clue for enterohepatic circulation.
Evaluate Piroxicam: It is a classic example of an NSAID with a very long half-life (around 2 days) specifically because of this recycling process.
Evaluate the other options: Aspirin and Ibuprofen are known for their short half-lives. Phenylbutazone, while long-acting, is known more for its toxicity and protein binding.
Conclude that Piroxicam is the best fit among the choices for an NSAID that undergoes significant enterohepatic circulation.

Concept Tested & Keywords

Concept Tested: Pharmacokinetics of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)
Stem keywords: NSAID, enterohepatic circulation
Lead-in keywords: Which

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