Post-Marketing Data Confirms Patiromer Safety in Hyperkalemia

The potassium binder patiromer (Veltassa) was deemed safe and well-tolerated in patients with hyperkalemia, post-marketing data showed.

Since its approval in October 2015, real-world data from the past 4 years found the sodium-free drug had a similar safety profile as it did in the clinical trials, reported Matthew Weir, MD, of the University of Maryland School of Medicine in Baltimore, in a poster at the virtual National Kidney Foundation Spring Clinical meeting.

"Real-world clinical experience may differ from clinical trial experience," Weir and colleagues explained. "Therefore, a global pharmacovigilance database has been established to report, document, and evaluate post-marketing experience with patiromer."

In a review of medically-confirmed reports of adverse events (AEs) from healthcare providers from January 2016 through September 2019, there were a total of 5,966 individual case safety reports accounting for 38,109 adverse events (AEs) over the course of 45,000 patient-years of exposure.

More than 85% of these case safety reports were among patients who used 8.4 grams of patiromer per day. More than half of these patients were male and the majority were older than age 65.

Looking at mortality data among real-world users of this potassium binder, there were 1,214 deaths reported, accounting for a cumulative annualized mortality rate of 2.69 per 100 patients-years. This mortality rate was almost half the rate that was seen in the 52-week clinical trial of patiromer (5.70 deaths per 100 patient-years).

Among these patients, the most common causes of death were due to heart-related problems: MI (2.7%), cardiac arrest (2.14%), cardiac failure (1.23%), cardiac disorders (0.82%), and congestive cardiac failure (0.82%). This was similar to what was seen in the patiromer clinical trial program, in which the most common causes of death were sudden cardiac death and acute MI, according to Weir and colleagues.

The second most common cause of mortality among real-world users of patiromer were renal disorders, including renal failure (2.8%) and end-stage renal disease (0.74%), although there were no renal-related deaths seen in the clinical trial.

For serious AEs, the most common events reported among real-world users were dialysis (0.69%) and pneumonia (0.58%). In contrast, there were no reports of dialysis in the clinical trial program because patients already on dialysis, or who potentially needed it, were excluded.

There was an overall lower rate of serious AEs seen among real-world users than compared with the clinical trial.

Lastly, for non-serious AEs, the two most common events reported among real-world users were constipation (6.9%) and diarrhea (3.48%), and both rates were lower than what was seen in the clinical trial program (7.2% and 4.8%, respectively).

Rates of hypokalemia -- or a serum potassium value less than 3.5 mEq/L -- was far less common in post-marketing data, only occurring in 0.45% of patients. During the clinical trial, this was reported in 4.7% of patients.

Similarly, rates of hypomagnesemia -- a serum magnesium level below 1.8 mg/dL -- were only reported in 0.02% of real-world users compared with 5.3% of those in the clinical trial.

"New patiromer trials, both currently ongoing (DIAMOND) and newly initiated (PLATINUM), will provide additional safety information on the use of patiromer to enable renin-angiotensin-aldosterone inhibitors for guideline-directed management of reduced ejection fraction heart failure and as adjunctive therapy for the management of severe hyperkalemia in the emergency room, respectively," the researchers wrote.

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