Ardelyx, Inc., a clinical-stage company, announced the initiation of a phase 3 clinical trial and an onset-of-action clinical trial evaluating RDX7675 in patients with hyperkalemia, a potentially life-threatening condition common in patients with cardiorenal disease.

"The phase 3 study for hyperkalemia marks the start of the fifth phase 3 clinical trial from our pipeline of internally developed, gut-restricted treatments in development," said Mike Raab, chief executive officer of Ardelyx. "Hyperkalemia is a difficult to treat and potentially devastating condition in patients with chronic kidney disease and/or heart failure. The initiations of the phase 3 and onset-of-action trials with RDX7675 are important steps forward for our cardiorenal portfolio, as we look to bring better treatments to underserved patients who aren't satisfied with their current care. We look forward to further evaluating its treatment potential and reporting data from the onset-of-action study in the first half of the year."

The phase 3 clinical trial is a randomized, single-blind, three-part study that will evaluate the efficacy and safety of RDX7675 in approximately 300 adult patients with hyperkalemia and includes a long-term, open-label safety extension. The onset-of-action trial is a single-blind, placebo controlled study evaluating the onset-of-action, safety and efficacy of RDX7675 in 60 patients with hyperkalemia.

RDX7675 is an oral, non-absorbed potassium-binding polymer that has demonstrated effective binding to potassium in pharmacodynamics studies in healthy volunteers. Using its unique chemistry, Ardelyx has developed RDX7675 as a patented improvement to sodium polystyrene sulfonate (SPS), an FDA approved polymer that has been the standard-of-care for the treatment of hyperkalemia for more than 50 years. The company made several key physical and chemical modifications to eliminate sodium and sorbitol, optimize binding capacity, greatly improve palatability and develop formulations that would taste pleasant and be easier to ingest. Ardelyx believes these improvements offer unique advantages for patients with hyperkalemia and could increase patient satisfaction and compliance.

Hyperkalemia is defined as the presence of blood potassium levels greater than 5.0 mEq/L. Normal levels are 3.5 to 5.0 mEq/L. When hyperkalemia is severe, or above 7.0 mEq/L, there is a significantly increased risk of death because of the potential for heart conductance problems.

Hyperkalemia can be caused by a variety of sources. Kidney disease can result in the build-up of potassium in the blood. In addition, certain drugs such as the common blood pressure medications known as RAAS inhibitors, can cause hyperkalemia. RAAS inhibitors, though quite effective for controlling blood pressure, are often significantly reduced in patients, such as in those with chronic kidney disease (CKD) and/or heart failure (HF) whose potassium levels are elevated because of the fear that elevated potassium can have serious results including sudden cardiac arrest in severe cases.  Reports in the literature suggest that hyperkalemia may affect about 900,000 individuals with CKD Stage 3b or Stage 4 as well as up to an additional 900,000 patients with HF in the United States. Ardelyx's proprietary research also suggests that up to 200,000 patients with end-stage renal disease (ESRD) could benefit from an agent that treats hyperkalemia.

Ardelyx is focused on enhancing the care and well-being of underserved patients with gastrointestinal (GI) and cardiorenal diseases by using the gut as the gateway to developing high-quality therapeutics.