Which of these medications can harm the kidneys?

Nephrotoxic Medications in This Regimen

The medications in this list that can harm the kidneys are: NSAIDs (if used), Fleet enema (sodium phosphates), furosemide, lisinopril, Xarelto (rivaroxaban), and acetaminophen (at high doses or with chronic use). 1, 2, 3

High-Risk Nephrotoxic Agents

Fleet Enema (Sodium Phosphates)

• Sodium phosphate enemas carry significant nephrotoxicity risk through acute phosphate nephropathy, particularly in elderly patients or those with pre-existing kidney disease 1
• This patient appears to be on multiple medications suggesting advanced age and comorbidities, placing them at higher risk
• Consider polyethylene glycol (GlycoLax, already on the list) as a safer alternative for constipation management 1

Furosemide

• The FDA label explicitly warns that furosemide can lead to deterioration in renal function, particularly in high-risk patients 3
• Can cause reversible elevations of BUN and is associated with dehydration, which should be avoided in patients with renal insufficiency 3
• When combined with ACE inhibitors (lisinopril is on this list), may lead to severe hypotension and deterioration in renal function, including renal failure 3

Lisinopril (ACE Inhibitor)

• Creates a "triple whammy" effect when combined with furosemide (diuretic) and any NSAID, significantly increasing acute kidney injury risk 2
• Can cause functional decline in GFR at treatment onset, though this is generally considered acceptable trade-off for long-term renoprotection 4
• The combination with furosemide requires close monitoring, as both drugs together may cause severe hypotension and renal function deterioration 3

Acetaminophen

• Nephrotoxic at high doses or with chronic use, particularly in patients who are glutathione-depleted (chronic alcohol use, malnutrition, fasting) 2, 5
• Current dosing (650mg every 6 hours, max 3000mg/day) is within safer limits, but still requires monitoring 5
• Can manifest as acute tubular necrosis, typically reversible but may worsen over 7-10 days 5

Moderate-Risk Medications

Xarelto (Rivaroxaban)

• Requires dose adjustment in renal impairment
• Can contribute to nephrotoxicity risk, particularly when combined with other nephrotoxic agents 6

Magnesium-Containing Products

• Milk of Magnesia and Magnesium Oxide require caution in patients with reduced kidney function due to risk of hypermagnesemia 3
• Magnesium is renally eliminated and can accumulate with impaired kidney function

Critical Drug Combinations to Monitor

The "Triple Whammy"

• This patient has lisinopril + furosemide already, adding any NSAID would create the dangerous triple combination 2
• Ensure no NSAIDs are used (the list appropriately avoids them, using acetaminophen and lidocaine patch instead) 1

Polypharmacy Risk

• Exposure to three or more nephrotoxic drugs daily significantly increases acute kidney injury risk 2
• This patient is on at least 3-4 nephrotoxic agents simultaneously (lisinopril, furosemide, Fleet enema as needed, acetaminophen)

Monitoring Recommendations

• Monitor serum creatinine, BUN, and electrolytes (particularly potassium and magnesium) regularly given the combination of ACE inhibitor and diuretic 3
• Check renal function before and after Fleet enema use 1
• Ensure adequate hydration status, as volume depletion potentiates nephrotoxicity of multiple agents on this list 3, 7
• Monitor for signs of acute kidney injury: decreased urine output, rising creatinine, electrolyte abnormalities 1

Safer Alternatives

• Replace Fleet enema with additional polyethylene glycol (GlycoLax) for step 3 of constipation protocol 1
• Continue using acetaminophen and topical lidocaine (both on list) instead of NSAIDs for pain management 1
• The current pain regimen appropriately avoids NSAIDs, which is critical given the ACE inhibitor + diuretic combination 1, 2