Which medication can cause hypokalemia: Lasix (furosemide), Flomax (tamsulosin), propranolol, spironolactone, or Valsartan?

Medication That Causes Hypokalemia

Among the medications listed (Lasix, Flomax, propranolol, spironolactone, and valsartan), Lasix (furosemide) is the only one that commonly causes hypokalemia. 1

Mechanism of Hypokalemia with Furosemide (Lasix)

• Furosemide is a loop diuretic that inhibits sodium and chloride reabsorption in the ascending limb of the loop of Henle 2
• This mechanism increases urinary excretion of potassium, which can lead to hypokalemia 1
• Hypokalemia is one of the most common adverse effects of furosemide therapy, occurring in approximately 3.6% of patients 3
• The risk of hypokalemia increases with higher doses of furosemide 1, 4

Risk Factors for Furosemide-Induced Hypokalemia

• Higher dosages of furosemide (dose-dependent effect) 1, 4
• Female gender 4
• Black ethnicity 4
• Concomitant use of corticosteroids 1
• Concomitant use of ACTH 1
• Prolonged use of laxatives 1
• Cirrhosis 1
• Inadequate oral electrolyte intake 1

Clinical Manifestations of Hypokalemia

• May range from asymptomatic to severe symptoms 4
• Common symptoms include muscle weakness, cramps, fatigue 1
• Can cause cardiac arrhythmias, especially in patients on digitalis therapy 1
• May present with hypotension, lethargy, drowsiness 1
• Can exacerbate CO2 retention in patients with chronic lung disease 2

Prevention and Management of Furosemide-Induced Hypokalemia

• Regular monitoring of serum electrolytes, particularly potassium 1
• Potassium supplementation (potassium chloride) 5
• Low-salt diet rich in potassium 5
• Use of lower doses of furosemide when possible 5
• Combination with potassium-sparing diuretics like spironolactone 2

Other Medications in the List and Their Effects on Potassium

• Spironolactone: Actually causes potassium retention and can lead to hyperkalemia 2
• Propranolol: Not typically associated with significant potassium abnormalities 2
• Flomax (tamsulosin): Not associated with potassium abnormalities 2
• Valsartan: Can cause hyperkalemia rather than hypokalemia 2

Important Considerations

• When furosemide is combined with spironolactone, the risk of hypokalemia is reduced 6
• The combination of furosemide with potassium-sparing diuretics helps maintain normal potassium levels 2
• Acute kidney injury and hypokalemia (potassium ≤3.0 mmol/L) are more common in patients receiving furosemide 7
• Digitalis therapy may exaggerate the cardiac effects of hypokalemia 1