New trial of Neridronate for CRPS announced

We have written previously of the benefits experienced by some people suffering CRPS who have undergone infusions of the bisphosphonate drug, Neridronate (also referred to as neridronic acid). Bisphosphonates prevent or slow down the loss of bone density.


German pharmaceutical company Grünenthal, which is developing Neridronate for the US market, has commenced two Phase III clinical trials of the drug.

In a press release, Grünenthal’s chief executive, Gabriel Baertschi, said:

There is a huge unmet medical need in CRPS as this condition may result in loss of the physical function and may lead to significant and sometimes permanent disability. Neridronate has been granted Breakthrough Therapy and Fast Track designation by the FDA and our pivotal phase III development program is the next step to investigate neridronate’s potential to make a difference in the lives of patients affected by this debilitating disease.

Professor Claudia Sommer, International Coordinating Investigator for one of the trials added:

I’m excited to be part of a pivotal phase III efficacy trial in CRPS. Currently, there is no approved treatment available and affected patients face a permanently high pain level and immense restrictions in their daily life. If the efficacy of neridronate is confirmed, quality of life of the patients could be significantly improved.

Phase III

Phase III trials are those that compare the efficacy and safety of a new treatment with the standard treatment for the condition. Following a successful Phase III trial a drug is usually granted a licence before moving to Phase IV to further study and assess longer term risks and side effects.

The two trials will investigate the drug’s effect on pain, as well as other symptoms of CRPS such as allodynia and oedema. Around 360 patients will be involved, each undergoing treatment over a twelve week period, with the degree of any improvement being assessed.


Neridronate is currently licensed for treatment in Italy. As reported previously, research conducted there in 2012 produced some startlingly positive results. However, those trials involved CRPS Type 1 only and all participants had been suffering from the condition for less than 4 months. As Libby Parfitt stated in her excellent article:

The Italian team freely admit that those who’ve had CRPS for longer may not experience the same results but they claim that the treatment is “still effective” even for those who’ve had CRPS for years. There are no published papers on trials involving neridronate with patients who have longstanding CRPS, but there are papers on other bisphosphonates that suggest that the treatment might benefit them. It’s just likely that the effect will not be as pronounced as the “cure” patients with younger CRPS might experience.

Other bisphosphenates

Grünenthal’s announcement comes only 6 months after a multiple-centre trial of another bisphosphonate drug for the treatment of CRPS, Zoledronate (also known as Zoledronic Acid), was halted by the pharmaceutical company, Axsome Therapeutics. The reason given for halting that trial was “futility”; in other words, the data collected to that point suggested that the trial was not going to meet its objectives.

However, as we reported recently, the bisphosphonate Pamidronate, which more often is used to treat secondary bone cancer, continues to be used to also treat early stage CRPS. Indeed, in the UK, pain medicine consultants in some NHS Trusts are now referring patients with early stage CRPS for a infusions of Pamidronate whilst maintaining their general regime of medication and physical therapy.

In the meantime, the results of Grünenthal’s trials are awaited keenly.

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