MILAN, Italy — The addition of spironolactone as a treatment option for patients with resistant hypertension and diabetes mellitus can help significantly lower blood pressure, according to the results of a new study.

These difficult-to-treat patients, all of whom were well treated in some combination with diuretics, ACE inhibitors, angiotensin-receptor blockers (ARBs), calcium-channel antagonists, and beta-blockers, had their systolic and diastolic blood pressure significantly reduced without an increased risk of adverse events, report investigators.

Dr Christina Oxlund (Odense University Hospital, Denmark), the lead researcher, presented the results during the late-breaking clinical-trials session here at the European Society of Hypertension (ESH) 2013 Scientific Sessions . The study included patients with diabetes and a baseline blood pressure >130/80 mm Hg despite treatment with three or more antihypertensive medications. In total, 61 patients were randomized to receive spironolactone 25 mg and 58 patients to a placebo. The dose of spironolactone was up- or downtitrated as needed, and 44% of patients ended up being treated with the 50-mg dose.

All patients received a diuretic, with 51% receiving hydrochlorothiazide, and 51% were treated with an ACE inhibitor, 38% with an ARB, 50% with a beta-blocker, and 84% with a calcium-channel blocker.

"At four months, systolic blood pressure was unchanged in the placebo arm but significantly reduced in the spironolactone group," said Oxlund. "The same was observed in the case of diastolic blood pressure. Daytime blood pressure measured by 24-hour ambulatory blood-pressure monitoring was our primary end point and was reduced by 8.9/3.7 mm Hg. Other measures were also reduced, in particularly nighttime blood pressure, which was reduced to a similar extent."

The maximum reduction in blood pressure, said Oxlund, was achieved after eight weeks. From this point on, no further changes were observed.

Regarding important secondary end points, the researchers did observe an increase in plasma potassium levels, which significantly increased 0.3 mmol/L in the spironolactone group but not in the placebo arm. Plasma creatinine levels also significantly increased, up 6 µmol/L in the spironolactone arm. However, the reduction in the estimated glomerular filtration rate (eGFR) was not significantly different between the two groups. Urinary albumin excretion was significantly reduced in the spironolactone-treated patients.

"The most prevalent side effect was, as expected, hyperkalemia," said Oxlund. "This led to dose discontinuation in one case and dose reduction in three cases. Spironolactone was discontinued in one patient because of severe hypotension. We saw no cases of gynecomastia in the trial."

Overall, Oxlund said the treatment appears to be safe and well tolerated in this difficult-to-treat group of patients and that larger studies should be conducted to determine whether the drug can provide additional clinical benefit for patients with resistant hypertension.


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