Readers need to be aware of a new vitamin D drug, Rayaldy, currently in phase III trials, which will possibly hit the market in a few years. In its current phase III trials, it is seeking an indication for the treatment of secondary hyperparathyroidism in vitamin D deficient chronic renal failure patients.
It passed phase II trials easily:
It recently surpassed 50% enrollment in the second of its two Phase III trials.
So what is exactly is Rayaldy? Rayaldy is a modified release form of the 25(OH)D molecule.
It is not an analog, it is the 25(OH)D molecule. That means the body will metabolize it to activated vitamin D and it will generate the same steroid signal as does activated vitamin D3.
25(OH)D used to be available as a drug in this country but it was discontinued about 15 years ago. For those who used it, such as Professor Robert Heaney at Creighton, 25(OH)D was useful, as it was more potent and got 25(OH)D levels up quicker than plain vitamin D3.
The current phase III trial is using 30 ug/day of Rayaldy. If you do the calculation, using a conversion factor of 5 for the relative potency of D3 vs. 25(OH)D, 30 ug/day of Rayaldy is equivalent to 7,000 IU/day of D3.
If Rayaldy passes phase III trials, and I predict it will, it may make a big impact on medical care. I wish that vitamin D3 would do that, but it may not, at least in the USA. When Rayaldy is available, it will be a prescription for a more potent and quicker acting D3 compound. Doctors can and will prescribe it off label. That means once it is available, doctors can legally use it for more than just treating secondary hyperparathyroidism. They can prescribe it for whatever they want, for things like multiple sclerosis, lupus, heart failure and more.
When a person goes to the doctor, neither the patient nor the doctor is usually satisfied if the doctor simply says go get some vitamin D at the pharmacy. It is not the way the doctor-patient transaction works in the United States. The patient wants a prescription and the doctor wants to write one.
That’s why I predict Rayaldy will make a big impact on modern medical care. Seven thousand IU/day of D3 will treat a lot of disease. Doctors may finally put a vitamin D compound to use if there is a prescription drug that has indications beyond just treating vitamin D deficiency. If the makers of Rayaldy choose to seek further treatment indications, doctors may end up prescribing 25(OH)D for a variety of diseases.