Restarting Spironolactone After Acute Illness: A Clinical Guide

What the label specifies

The Aldactone label says to monitor serum potassium within 1 week of starting or titrating the drug and regularly thereafter, with more frequent monitoring when it is given with other drugs that cause hyperkalemia or to patients with impaired renal function [1]. Hyperkalemia is also a contraindication [1].

In heart failure, the label starts treatment at 25 mg once daily when serum potassium is at or below 5.0 mEq/L and eGFR is above 50 mL/min/1.73 m2. At an eGFR of 30 to 50 mL/min/1.73 m2 it suggests considering 25 mg every other day [1]. These are heart failure instructions, not acne instructions [1].

Medicines started during an illness that raise potassium

The label names ACE inhibitors, angiotensin receptor blockers, NSAIDs, heparin and low molecular weight heparin, and trimethoprim among drugs that can increase potassium. It states that combining potassium-raising drugs or potassium supplements with spironolactone can lead to severe hyperkalemia [1]. Potassium-containing salt substitutes are also listed as raising the hyperkalemia risk [1].

The label says to check potassium when ACE inhibitor or ARB therapy is altered, and in general to discontinue potassium supplementation in heart failure patients who start the drug [1]. It also warns that excessive diuresis can cause symptomatic dehydration, hypotension and worsening renal function, particularly in salt-depleted patients or those taking ACE inhibitors or ARBs [1].

What the acne data show about potassium

Plovanich and colleagues reviewed 974 healthy young women taking spironolactone for acne. They found 13 abnormal potassium values in 1,802 measurements (0.72%), against a 0.76% baseline rate in 1,165 comparison women. Six of the 13 abnormal values were normal on repeat, and the authors concluded routine monitoring had low usefulness in this group [3]. Women with heart or kidney disease and women taking drugs that act on the renin-angiotensin-aldosterone system were excluded [3]. The Aldactone label itself still advises potassium monitoring [1].

SAFA randomized 410 women aged 18 or older, 201 to spironolactone and 209 to placebo. The spironolactone group took 50 mg daily through week 6, then 100 mg daily through week 24 [2]. Headache was reported more often with spironolactone than with placebo (20.4% vs 12.0%) [2].