Diltiazem and Hyperkalemia
- M. R. Flicker, MD, PhD;
- M. A. Quigley, PhD;
- E. G. Caldwell, MD
Since this article does not have an abstract, we have provided the first 150 words of the full text.
Excerpt
To the Editor.— In his Letter,1 Dr Hoyt speculates that therapy with the calcium antagonist diltiazem may have exacerbated hyperkalemia in a 70-year-old patient treated with metoprolol who was consuming massive quantities of potassium as salt substitute. We wish to suggest that there is insufficient evidence to postulate a role for diltiazem therapy in such a clinical setting.
Metoprolol treatment is likely to have contributed to the patient's hyperkalemia. Although the author argues against this possibility on the basis of metoprolol's β1-specificity, loss of such specificity has been well described2 at daily doses of 100 mg or more (the patient was receiving 200 mg/d). Administration of 100-mg doses of metoprolol has been shown to parallel propranolol's tendency to augment the exercise-induced rise in serum potassium level,3 while administration of 200mg daily doses of metoprolol may cause a significant rise in the resting serum potassium level.4
Advanced
