Mannstadt Lab

October 4, 2022

Today, Takeda announced the discontinuation of Natpara at the end of 2024. The notice can be found here.
The notice mentioned several reasons:

  1. The challenges surrounding the protein particles which already interrupted the production of the 100-mcg dose cartridge and
  2. The separate issue of the rubber particles.

But there is good news: Takeda is producing Natpara through 2024, which gives plenty of time to find alternatives (yes, and plenty of time worrying, too). And we might have a new drug on the market by then (Transcon PTH) and at least another one in development (AZP-3601). Ascendis Pharma submitted a New Drug Application for Transcon PTH to the FDA on August 31, 2022.

What are options for AFTER Natpara is no longer available (currently estimated to be some time after 2024)? Please see also more details in my post of September 8, 2019.

  1. If is available by then, transition to Transcon PTH. To my knowledge, transitioning from PTH to Transcon PTH has not been studied, so there is currently no “protocol” for it. Patients probably need several days of overlap: start Transcon PTH but continue Natpara. Check albumin-adjusted serum calcium after two days and, depending on the results, either reduce or discontinue Natpara.
  2. Transition to Forteo (PTH1-34). PTH1-34 has been used for hypoparathyroidism in clinical trials but is not FDA approved for hypoparathyroidism. Because of a relatively short half-life, twice- or even three times daily injections are typically needed.
  3. Transition to calcium/calcitriol. When stopping Natpara and switching to oral calcium and calcitriol, some patients transiently require much higher doses of calcium/calcitriol than before starting Natpara.

With all the worries and sadness around the discontinuation of Natpara, let’s not forget that this drug has been an important milestone for hypoparathyroidism. It demonstrated that drugs could be developed and approved for this rare (but not super-rare) disease; it led to many scientific studies on hypoparathyroidism and long-term complications, and it inspired the development of the next-generation PTH drugs. Thanks to all patients who participated in the diverse trials of Natpara (PTH 1-84). Thanks the scientists and companies that developed and marketed it; this must also be trying news for them.