Medication switching is recommended when screening for primary aldosteronism (PA), given commonly-used anti-hypertensives can cause a false-negative or false-positive aldosterone-renin ratio. The safety of medication switching has only been reported in a small study of 50 participants(1).
We sought to assess tolerability of medication switching in a retrospective study of 878 patients referred for PA investigation at Monash Health Endocrine Hypertension Clinic between 2020-2023. At the three-month follow-up, occurrence of adverse event and defined daily dose of antihypertensive medications (DDD) was extracted from clinic notes for the medication switching and non-medication switching group.
Of 878 patients, medication switching was not indicated in 330 patients, primarily because they were not taking antihypertensive medications at baseline (n=142) or were already taking non-interfering medications (n=130). Medication switching was indicated for the remaining 548, of whom 408 underwent switching (mean age 54 years, 53% female). Compared to the 140 patients who did not switch despite having an indication, those who underwent switching had significantly more adverse events (131 vs. 7, p=<0.001). 76% of adverse events occurred within three months of medication switching. The most common adverse events were new medication side effects (97/408) and uncontrolled blood pressure (BP) (44/408). Following an adverse event, 59 of 131 patients persisted with the treatment plan, 46 commenced an alternate agent, 49 abandoned medication switching, 10 presented to a general practitioner, 26 presented to emergency department, and 11 had a hospital admission. Acute target organ damage and major adverse cardiovascular events resulting from medication switching were not recorded. The DDD was one point lower in the medication switching group at three months.
Overall, a third of patients who underwent medication switching during PA investigation experienced adverse events, although none had a hypertensive emergency. A gradual, consistent strategy for medication up-titration may reduce side effects while avoiding uncontrolled BP.