The drug contains a nonabsorbable polymer that binds potassium throughout the gastrointestinal tract.
The new drug patiromer was randomly tested in an open-label phase 2 trial funded by Relypsa and the results are published in JAMA.
Those most at risk of hyperkalemia are patients with chronic kidney disease (CKD) who have diabetes, heart failure or both and are taking a form of medication called renin-angiotensin-aldosterone system (RAAS) inhibitors. RAAS inhibitors are typically taken to help slow the progression of renal disease in patients with diabetes.
At present, there are few options available when it comes to managing hyperkalemia, and so doctors will often stop patients from using RAAS inhibitors or prescribe them in doses lower than the recommended amount.
Patiromer could change this. It is an orally administered drug that contains a nonabsorbed polymer that increases the amount of potassium excreted in the stool, thereby lowering potassium in the blood.
Previous trials have demonstrated the drug's efficacy in other at-risk populations such as patients with heart failure and patients with CKD for periods ranging from a few days to up to 12 weeks.
For the new study, Dr. George L. Bakris of the University of Chicago Medicine and colleagues randomly assigned a total of 306 patients the drug, to be taken twice daily for 8 weeks. The patients all had type 2 diabetes, hyperkalemia and received RAAS inhibitors before and during the study.
After taking the drug for 4 weeks, the patients were observed for adverse events through to 52 weeks.
Patients received 1 of 3 different starting doses of patiromer. In every dose group, ranging from patients receiving 8.4 g to those receiving 33.6 g of the drug each day, the researchers found patiromer significantly reduced potassium levels.
'A viable new and effective approach'
Potassium levels decreased significantly over the 4 weeks of treatment and normal levels of potassium were maintained over 52 weeks from the beginning of the study period.
The researchers state that 20% of the study participants reported adverse events considered to be related to the drug. The most common events were abnormally low levels of magnesium in the blood (in 7% of patients), mild to moderate constipation (in 6% of patients) and abnormally low levels of potassium in the blood (in 6% of patients).
"Worsening of CKD was the most frequently reported adverse event during the trial and the most common adverse event during the trial and the most common adverse event leading to discontinuation," write the authors.
"However, most of these adverse events occurred during the long-term maintenance phase, suggesting that the progression of underlying CKD may have been contributory."
A limitation of the study is a lack of blinding that may have led to observer bias, but the authors argue using a placebo control would have subjected some study participants to the potentially life-threatening risks of hyperkalemia.
In an accompanying editorial, Dr. Wolfgang C. Winkelmayer, of Baylor College of Medicine in Houston, TX, states that the study's findings indicate the patiromer could represent "a viable new and effective approach to management of hyperkalemia."
The question whether or not the development of hyperkalemia in patients receiving RAAS inhibitors is an inevitable outcome regardless of treatment is currently unknown. Dr. Winkelmayer believes that if patiromer becomes widely available, it could be used to find an answer.
Earlier this year, Medical News Today reported on a study in the American Journal of Kidney Diseases finding that more than half of middle-aged adults in the US are at risk of developing CKD at some point in their lifetime.