What medications should be discontinued in a patient with impaired renal function (creatinine 1.9), hypokalemia (potassium 3.5), and other electrolyte imbalances?

Medication Discontinuation in Renal Impairment

Immediate Discontinuation Required

Based on your creatinine of 1.9 (estimated GFR approximately 30-40 mL/min/1.73 m²), metformin must be discontinued immediately if you are taking it. 1, 2

Metformin - Mandatory Discontinuation

• Metformin is contraindicated when eGFR falls below 30 mL/min/1.73 m² and must be discontinued. 2
• With a creatinine of 1.9, your eGFR is likely in the 30-45 mL/min/1.73 m² range, placing you in the high-risk zone where metformin accumulation can cause life-threatening lactic acidosis. 1, 2
• The FDA explicitly states: "Discontinue metformin hydrochloride tablets if the patient's eGFR later falls below 30 mL/minute/1.73 m²" and initiation is not recommended between 30-45 mL/min/1.73 m². 2
• Lactic acidosis from metformin is a medical emergency with symptoms including unusual muscle pain, trouble breathing, unusual sleepiness, unexplained nausea/vomiting, feeling cold, dizziness, and slow/irregular heartbeat. 2

NSAIDs - Discontinue Immediately

• All NSAIDs (ibuprofen, naproxen, ketorolac, indomethacin, celecoxib) must be discontinued with your level of renal impairment. 1, 3
• The KDOQI guidelines specifically state NSAIDs should be avoided in patients with GFR <60 mL/min/1.73 m² for prolonged therapy. 3
• NSAIDs cause acute kidney injury through prostaglandin inhibition, reducing renal blood flow when kidneys are already compromised. 3, 4
• The risk is dramatically increased if you are taking ACE inhibitors, ARBs, or diuretics - this "triple whammy" combination significantly increases acute kidney injury risk. 3

First-Generation Sulfonylureas - Discontinue Immediately

• Chlorpropamide, tolazamide, and tolbutamide accumulate dangerously in stage 4 CKD and cause prolonged, severe hypoglycemia. 1
• These must be stopped immediately and replaced with safer alternatives like glipizide if sulfonylurea therapy is needed. 1

Medications Requiring Immediate Dose Reduction

Digoxin - Reduce Dose Significantly

• With your creatinine of 1.9, digoxin clearance is substantially reduced, requiring dose reduction to prevent life-threatening toxicity. 5
• Maintenance doses should not exceed 0.125 mg/day in patients ≥75 years without renal impairment; lower doses are needed with your renal function. 5
• Your borderline low potassium (3.5 mEq/L) increases digoxin toxicity risk - hypokalaemia, hypomagnesaemia, and hypercalcaemia are major risk factors. 5
• Monitor ECG and renal function closely; serum levels >1.0 ng/mL provide no additional benefit and increase toxicity risk. 5

Aldosterone Antagonists (Spironolactone/Eplerenone) - Extreme Caution

• With creatinine 1.9 (eGFR likely 30-49 mL/min/1.73 m²), aldosterone antagonists require dose reduction to 12.5-25 mg once daily or every other day. 5, 1
• Your potassium is already at the lower limit of normal (3.5 mEq/L), but with declining renal function, the risk of hyperkalemia increases dramatically. 5
• These medications are contraindicated if serum creatinine exceeds 2.5 mg/dL in men or 2.0 mg/dL in women, or if potassium exceeds 5.0 mEq/L. 5
• Discontinue all potassium supplements immediately if continuing aldosterone antagonists, and monitor potassium within 2-3 days, at 7 days, then monthly. 5

Insulin - Reduce Dose by 25-50%

• Impaired renal function prolongs insulin half-life because one-third of insulin degradation occurs in the kidneys. 1
• Reduce insulin doses by 25-50% and intensify glucose monitoring to prevent severe hypoglycemia. 1

Medications Requiring Temporary Discontinuation During Acute Illness

• ACE inhibitors, ARBs, aldosterone antagonists, diuretics, and SGLT2 inhibitors should be temporarily stopped 48-72 hours before elective surgery or during acute illness that increases AKI risk. 1
• This "sick day protocol" prevents acute kidney injury during periods of volume depletion or hemodynamic instability. 1

Additional High-Risk Medications to Avoid

Herbal Remedies and Supplements

• Stop all herbal remedies completely - they lack safety data and have unpredictable nephrotoxic potential. 1
• Avoid nutritional protein supplements without medical supervision due to hyperphosphatemia risk. 1

Aminoglycoside Antibiotics

• If prescribed aminoglycosides (gentamicin, tobramycin, amikacin), dosing frequency must be reduced to 2-3 times weekly with dose maintained at 12-15 mg/kg, and serum drug concentrations must be monitored. 5
• These should be given after dialysis if you require hemodialysis. 5

Capreomycin (if on TB treatment)

• Dosing frequency must be reduced to 2-3 times weekly at 12-15 mg/kg per dose, with close monitoring of potassium and magnesium levels monthly. 5

Critical Monitoring Requirements

• Check eGFR, electrolytes (especially potassium), and medication levels regularly - at minimum monthly for the first 3 months, then every 3 months. 5, 1
• Your low-normal sodium (132 mEq/L) and borderline low potassium (3.5 mEq/L) require close monitoring as renal function changes. 5
• Establish collaborative care with a clinical pharmacist for medication management in CKD. 1

Common Pitfalls to Avoid

• Never combine NSAIDs with ACE inhibitors/ARBs and diuretics - this "triple whammy" dramatically increases acute kidney injury risk. 3
• Do not assume over-the-counter medications are safe - many contain NSAIDs or are nephrotoxic. 1, 3
• Avoid dehydration, which significantly increases nephrotoxicity risk of all medications. 3, 2
• Stop metformin before any iodinated contrast imaging procedure and don't restart until renal function is confirmed stable 48 hours later. 2