In a 76-year-old man with stage 4 chronic kidney disease (eGFR 22 mL/min/1.73m2) who needs an oral anticoagulant for stroke prevention in atrial fibrillation, which drug would be contraindicated based on his renal function?

• A. Rivaroxaban
• B. Apixaban
• C. Dabigatran
• D. Edoxaban

Answer: (C)

In this scenario, the key idea is how kidney function affects the safety of direct oral anticoagulants. Drugs that are cleared mainly by the kidneys can accumulate when the GFR is very low, increasing bleeding risk. Dabigatran stands out because about 80% of it is eliminated unchanged by the kidneys. With an eGFR of 22 mL/min/1.73 m2 (stage 4 CKD), dabigatran would accumulate and pose a high bleeding risk, making it contraindicated.

The other options are renally cleared to a lesser extent and have recommended dose adjustments for impaired renal function, so they are not categorically contraindicated at this level of kidney function. Rivaroxaban, apixaban, and edoxaban can be used with dose modifications depending on the exact creatinine clearance.

So the drug that would be contraindicated based on this patient’s renal function is the one that relies most heavily on renal excretion, leading to drug accumulation and bleeding risk at a CrCl around 20.