In a client with low potassium levels, which medication is most likely to cause decreased potassium?

The choice of prednisone as the medication most likely to cause decreased potassium levels can be understood through its effects as a corticosteroid. Corticosteroids like prednisone can lead to potassium loss primarily through their action on the kidneys, where they can promote sodium retention and potassium excretion. This can result in a condition known as hypokalemia, or low potassium levels, particularly with high doses or long-term use.

In contrast, the other medications listed have different affects on potassium levels. Spironolactone and triamterene are diuretics known as potassium-sparing agents, which actually help retain potassium in the body rather than cause its depletion. Lisinopril, an ACE inhibitor, generally does not lead to a decrease in potassium levels and can even increase potassium levels in some cases by reducing aldosterone secretion, which normally promotes potassium excretion.

Therefore, assessing the pharmacologic actions of each medication helps clarify why prednisone is most likely to lead to decreased potassium levels in a client.