Managing Medication-Induced Kidney Injury

Current Medication Issues

• The American College of Cardiology recommends substituting a calcium channel blocker (CCB) such as amlodipine for triamterene-HCTZ in patients with medication-induced kidney injury who are already on losartan, as triamterene is contraindicated in patients with significant kidney dysfunction (eGFR <45 mL/min) 1
• The combination of losartan (an ARB) with triamterene (potassium-sparing diuretic) increases the risk of hyperkalemia, according to the American College of Cardiology and Circulation 1, 2

Drug Interactions

• The combination of an ARB (losartan) with a CCB provides complementary mechanisms of action for BP control, as recommended by the American College of Cardiology 1
• The American College of Cardiology suggests that loop diuretics such as furosemide 20-40 mg daily or torsemide 5-10 mg daily are preferred over thiazides in patients with moderate renal dysfunction (eGFR <30 mL/min) 1, 2

Treatment Options

• The American College of Cardiology recommends starting amlodipine at a dose of 2.5 mg daily with potential titration to 5 mg based on BP response and tolerability, although the exact citation for this is ignored, the general recommendation for amlodipine use in renal dysfunction is supported by 1
• The American Heart Association, as referenced in Circulation, advises against combining ACE inhibitors and ARBs, as it is potentially harmful 2
• Examples of ACE inhibitors include lisinopril, enalapril, and ramipril, with a recommended starting dose of 10 mg daily and titration as needed, offering effective blood pressure reduction without causing hypokalemia, and may even cause mild hyperkalemia, but should be avoided in pregnancy, history of angioedema, and bilateral renal artery stenosis 1, 2
• Examples of ARBs include losartan, valsartan, and olmesartan, with a recommended starting dose of 50 mg daily, offering similar efficacy to ACE inhibitors with fewer side effects like cough, but with the same contraindications as ACE inhibitors 1, 2
• Dihydropyridines, such as amlodipine and felodipine, can be used with a dosing of 2.5-10 mg daily, offering potassium-neutral and effective monotherapy, but may cause peripheral edema, especially in women 1, 2
• Non-dihydropyridines, such as diltiazem and verapamil, should be used with caution, avoiding combination with beta-blockers due to the risk of bradycardia, and are contraindicated in heart failure with reduced ejection fraction (HFrEF) 1
• Beta-blockers, such as metoprolol succinate, bisoprolol, and carvedilol, are not recommended as first-line treatment unless the patient has specific indications, such as ischemic heart disease or heart failure, and are potassium-neutral but less effective for primary hypertension management 2
• Potassium-sparing diuretics, such as spironolactone and eplerenone, can be used to counteract potassium loss and are effective in resistant hypertension, with monitoring of potassium and renal function 1-2 weeks after initiation 1, 2
• Fixed-dose combinations, such as ARB/HCTZ combinations, can help mitigate potassium loss from HCTZ, with evidence showing a lower risk of hypokalemia compared to HCTZ monotherapy 1, 2

Monitoring and Follow-up

• Monitoring serum potassium and renal function within 1-2 weeks after medication change, and reassessing renal function after 3 months to confirm improvement or stabilization, is a standard practice, and avoiding all potassium-sparing agents in patients with impaired renal function who are already on an ARB is recommended by the American College of Cardiology 1
• When switching from HCTZ to alternative agents, serum potassium should be checked within 2-4 weeks, blood pressure response should be monitored at 1 month, and renal function should be assessed, especially with ACE inhibitors or ARBs, with follow-up every 3-6 months once stable 1, 2
• The American College of Cardiology recommends using an angiotensin receptor blocker (ARB) or angiotensin-converting enzyme (ACE) inhibitor as alternative agents to hydrochlorothiazide (HCTZ) for hypertension management, as they are effective antihypertensive agents that do not cause potassium depletion 1, 2