A 58-year-old man with chronic kidney disease (eGFR 25 mL/min/1.73m²) and hypertension requires an antihypertensive agent. Which drug is the preferred choice considering its pharmacokinetic profile and renal handling?

Explanation

## Pharmacokinetic Considerations in Renal Impairment **Key Point:** Amlodipine is the preferred antihypertensive in advanced CKD because it undergoes hepatic metabolism with minimal renal excretion, requiring no dose adjustment. ### Drug Metabolism Pathways | Drug | Metabolism | Renal Excretion | CKD Adjustment | Preferred in CKD | |------|-----------|-----------------|-----------------|------------------| | Amlodipine | Hepatic (CYP3A4) | <10% unchanged | None | ✓ Yes | | Enalapril | Hepatic (prodrug) | Active metabolite renally cleared | Yes, reduce dose | No | | Atenolol | Minimal metabolism | 85-90% renal | Yes, reduce dose | No | | Furosemide | Hepatic | 50% renal | Yes, increase dose | No | **High-Yield:** Calcium channel blockers (dihydropyridines like amlodipine) are ideal in renal disease because: 1. Hepatic metabolism is not significantly impaired 2. No active metabolite accumulation 3. No dose adjustment needed 4. Additional renal protection (afferent arteriole dilation) ### Why Amlodipine Wins **Clinical Pearl:** In CKD Stage 4 (eGFR 15–29), drugs dependent on renal clearance accumulate and cause toxicity. Amlodipine's hepatic metabolism makes it safe across all stages of renal disease. **Mnemonic:** **HEPATIC drugs in CKD** = Amlodipine, Diltiazem, Verapamil, Nifedipine (calcium channel blockers), Hydralazine, Methyldopa — all safe without dose adjustment. ### Mechanism of Renal Protection Amlodipine causes preferential dilation of the afferent arteriole, reducing intraglomerular pressure and slowing progression of nephropathy — an added benefit in this patient.