Biopharmaceutical company OPKO Health has launched a Phase II clinical trial to assess Rayaldee as a potential treatment for mild to moderate Covid-19.
The drug is an extended-release oral formulation of calcifediol, a prohormone of calcitriol, the active form of vitamin D3.
Rayaldee is said to be the first and only drug approved by the US Food and Drug Administration (FDA) to increase serum total 25-hydroxyvitamin D (25D) and decrease intact parathyroid hormone (iPTH) levels in blood.
It holds approval for the treatment of secondary hyperparathyroidism (SHPT) in adults with stage 3 or 4 chronic kidney disease (CKD) and vitamin D insufficiency.
Named REsCue, the randomised, double-blind, placebo-controlled Phase II trial is designed to investigate the safety and efficacy of extended-release capsules of Rayaldee to treat symptomatic Covid-19 patients.
The study is set to involve about 160 participants, many with stage 3 or 4 CKD who are at higher risk for developing more severe illness. It will be performed at various Covid-19 outpatient clinics across the US.
OPKO Health said that the initial sites are primarily in South Florida, the Central Gulf coast, the Midwest and the Southwest. The first participants are set to be enrolled within the coming weeks.
During the study, patients will receive Rayaldee or placebo for four weeks, with two weeks of follow-up. The drug will be given at a 300mcg dose per day on days one, two and three, followed by 60mcg per day on days four to 27.
The primary efficacy endpoints are raising and maintaining serum total 25D within the 50ng/mL to 100ng/mL range and time to the resolution of symptoms.
Secondary endpoints include incidence of emergency room or urgent care visits, oxygen saturation of less than 94%, the need for and duration of hospitalisation, and the need for mechanical ventilation.
In addition, the trial will track mortality rate and severity and duration of illness based on quality-of-life measures.