From the Guidelines
Not all antacids cause hypokalemia, but certain types can contribute to low potassium levels, particularly those containing aluminum hydroxide or calcium carbonate, which can lead to hypophosphatemia and metabolic alkalosis, resulting in potassium shifting into cells and lowering serum potassium levels 1.
Mechanisms of Hypokalemia
The mechanisms by which antacids can cause hypokalemia include:
- Binding to dietary phosphate in the gut, leading to hypophosphatemia, which causes potassium to shift into cells, lowering serum potassium levels
- Causing metabolic alkalosis, which promotes the exchange of extracellular hydrogen ions for intracellular potassium, further reducing serum potassium
- Causing diarrhea with prolonged use, leading to potassium loss through the gastrointestinal tract, particularly with magnesium-containing antacids
Patient Monitoring and Treatment
Patients taking antacids regularly, especially those with heart or kidney conditions or those on diuretics, should be monitored for hypokalemia, as symptoms can include muscle weakness, fatigue, and cardiac arrhythmias 1.
Prevention and Management
If hypokalemia develops, potassium supplementation may be necessary, and the antacid regimen should be reevaluated to prevent further potassium loss.
- Potassium supplements can be effective in maintaining body potassium stores during diuretic treatment, but their use should be monitored by repeated measurements of serum creatinine and potassium 1.
- Potassium-sparing diuretics, such as triamterene, amiloride, and spironolactone, can also be considered in cases of persisting diuretic-induced hypokalemia despite concomitant ACE inhibitor therapy, or in severe heart failure, despite concomitant ACE inhibition plus low-dose spironolactone 1.
From the Research
Causes of Hypokalemia
- Hypokalemia is caused by decreased intake, renal losses, gastrointestinal losses, or transcellular shifts 2
- Diuretic use and gastrointestinal losses are common causes of hypokalemia, whereas kidney disease, hyperglycemia, and medication use are common causes of hyperkalemia 3
Antacids and Hypokalemia
- There is no direct evidence in the provided studies that all antacids cause hypokalemia
- Antacids can produce drug interactions by changing gastric pH, thus altering drug dissolution of dosage forms, reduction of gastric acid hydrolysis of drugs, or alter drug elimination by changing urinary pH 4
- Most antacids, except sodium bicarbonate, may decrease drug absorption by adsorption or chelation of other drugs 4
Treatment of Hypokalemia
- Hypokalemia is treated with oral or intravenous potassium 3
- To prevent cardiac conduction disturbances, intravenous calcium is administered to patients with hyperkalemic electrocardiography changes 3
- Insulin, usually with concomitant glucose, and albuterol are preferred to lower serum potassium levels in the acute setting; sodium polystyrene sulfonate is reserved for subacute treatment 3