Question

Which of the following drug does NOT require therapeutic drug monitoring:

• A. Digitoxin
• B. Phenytoin
• C. Gentamicin
• D. Acetaminophen

Hint:

Therapeutic drug monitoring (TDM) is essential for drugs with a narrow therapeutic index, like Digitoxin, Phenytoin, and Gentamicin, but not for drugs like Acetaminophen with a wide therapeutic range.

Answer 1

The Correct Option is D

Step 1: Understanding therapeutic drug monitoring (TDM). Therapeutic drug monitoring is used for drugs with a narrow therapeutic index, where small changes in dosage can lead to toxicity or subtherapeutic effects. 

Step 2: Analysis of given drugs. - (A) Digitoxin: Requires TDM because of its narrow therapeutic index and risk of toxicity, especially in cardiac patients. 
- (B) Phenytoin: Requires TDM due to its non-linear pharmacokinetics and risk of toxicity at high serum levels. 
- (C) Gentamicin: Requires TDM to avoid nephrotoxicity and ototoxicity, especially in patients with renal impairment. 
- (D) Acetaminophen: Does not require routine TDM as it has a wide therapeutic index and predictable pharmacokinetics, except in cases of suspected overdose. 

Step 3: Conclusion. Acetaminophen is safe for most patients at therapeutic doses, making it the correct answer as the drug that does not require TDM.