麻豆传媒

BOSTON -- The hyperkalemia drug patiromer (Veltassa) was associated with a drop in blood pressure among diabetic patients with chronic kidney disease and resistant hypertension, according to a new study.

The drop in blood pressure was not entirely expected in the open-label, year-long trial, according to co-author , of drugmaker Relypsa, who presented the findings at a poster session during the National Kidney Foundation meeting.

Mean systolic blood pressure fell by 18.4 mmHg over the trial, and diastolic blood pressure fell by 10.1 mmHg, reported the authors. Those on the drug who had hypertension and hyperkalemia saw significant reductions in mean serum potassium even by day 3, and were able to sustain the reductions throughout the trial.

Wilson presented findings from a subanalyses that he and others -- including researchers from the University of Miami and the University of Chicago -- did that included 79 patients with diabetic nephropathy and resistant hypertension. The original trial, known as AMETHYST-DN, was published in the last July. Patiromer, a potassium binder used for treating hyperkalemia, has been on the market for only a little more than half a year.

"This was not a blood pressure trial per se, but blood pressure fell significantly over the course of the trial," said Wilson in an interview with 麻豆传媒. "But there were significant limitations -- there was no placebo group, for one."

The phase II study initially included 304 patients, all of whom had CKD and type 2 diabetes, but only 50 (63.3%) completed the study. Most of them (15.2%) withdrew their consent; 5.1% of them withdrew because of adverse events, and 5.1% withdrew because of low serum potassium. One patient discontinued because of recurrent hyperkalemia, the authors reported.

To be included, patients with a history of hypertension were required to have an average sitting systolic blood pressure of >130 to ≤180 and a diastolic blood pressure of >80 to ≤110 mmHg. Patiromer dosage started at 4.2 to 12.6 g for patients with mild hyperkalemia -- defined as serum potassium of >5.0 to 5.5 mEq/L -- and 8.4 to 16.8g in those with moderate hyperkalemia, with a serum potassium level of >5.5 to <6.0 mEq/L.

The researchers identified 79 patients with recurrent hypertension, somewhat defined as having systolic blood pressure of >140 mmHg at baseline and on at least four different classes of antihypertensive medications. Forty-nine patients had either phase 3a or 3b CKD, while 23 had phase 4 or 5. Half of the patients were male, and the mean age was 67.

In an editorial accompanying that earlier JAMA study, , of Baylor College of Medicine in Houston, wrote that the, "initial findings are encouraging and suggest that this agent may represent a viable new and effective approach to management of hyperkalemia."

But he added that more time is needed to fully understand the effects of patiromer. This was echoed by , of the University of Southern California Keck School of Medicine in Los Angeles, who wrote in an email to 麻豆传媒 that the long-term data would be very important.

"I would also like the researchers to do a study with more patients, and I would like for the researchers to do a blinded study where the patients and the researchers would not know who is getting patiromer," he wrote. "It would have been interesting to see whether similar results would be achieved if it was a closed label study."

He added that "other similar exchange resins such as Kayexalate" have the risk of bowel necrosis, and long-term data would tell us whether this was a risk with long-term use of patiromer or not.

Serious adverse events were reported in 20.3% of the patients -- with one death -- but none were considered by the investigators to be related to patiromer, according to Wilson and colleagues.

"A strategy focused on aggressive treatment of hyperkalemia may be an important component to the management of resistant hypertension in patients with diabetic kidney disease," they concluded.

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