護理師正在檢視病人的用藥史，注意到病人正在服用毛地黃（digoxin）。病人的血清鉀離子濃度為 3.2 mEq/L。護理師應對哪種潛在的副作用最為警惕？
A nurse is reviewing a client's medication history and notes the client is taking digoxin. The client's serum potassium level is 3.2 mEq/L. The nurse should be most alert for which potential adverse effect?
- AHyperkalemia高血鉀
- BHypoglycemia低血糖
- CBradycardia✓ 正解心搏徐緩
- DHypertension高血壓
毛地黃（digoxin）的治療指數狹窄，其作用機制是透過抑制鈉鉀幫浦（Na+/K+-ATPase）來增加心肌收縮力。當血清鉀離子過低（hypokalemia）時，鉀離子與毛地黃競爭受體位點的能力下降，導致更多的毛地黃結合在心肌細胞上，進而大幅增加藥物毒性。低血鉀是引發毛地黃毒性最常見的誘因，臨床上需特別警惕心律不整，其中以心搏徐緩（bradycardia）及心室早期收縮（PVCs）最為常見。
Digoxin has a narrow therapeutic index, and its mechanism of action involves inhibition of the Na+/K+-ATPase pump to increase myocardial contractility. When serum potassium is low (hypokalemia), the ability of potassium to compete with digoxin at receptor sites is diminished, allowing more digoxin to bind to myocardial cells and substantially increasing drug toxicity. Hypokalemia is the most common precipitating factor for digoxin toxicity, and clinically the nurse must remain alert for dysrhythmias, particularly bradycardia and premature ventricular contractions (PVCs).