Safety of Intravenous Neridronic Acid in CRPS

Inclusion Criteria: * Informed consent signed. * Male or female participant at least 18 years of age at Visit 1. * A diagnosis of complex regional pain syndrome according to the clinical diagnostic criteria recommended by the International Association for the Study of Pain (IASP; "Budapest clinical criteria"), assessed at Visit 1. Signs and symptoms of CRPS must apply to an affected limb (arm or leg) and must demonstrate asymmetry with respect to the contralateral limb. * Ongoing moderate to severe chronic pain, including a baseline current pain intensity score of greater than or equal to 4 using an 11-point Numerical Rating Scale, referring to the CRPS-affected limb, at Visit 2 (prior to dosing). * In stable treatment and follow-up therapy for CRPS for at least 1 month prior to allocation to treatment (Visit 2). Participants must have failed trials of at least 2 treatments for CRPS, one of which must be a pharmacologic treatment. * Women of child-bearing potential must have a negative urine beta-human chorionic gonadotropin (β-HCG) pregnancy test at Visit 1 and must be using 2 forms of medically acceptable contraception, including at least 1 highly effective method of contraception with a low failure rate, defined as less than 1% per year (e.g., oral contraceptives or intrauterine device), and a second medically acceptable method such as use of condoms with spermicide by their male partner. A barrier method alone is not acceptable. Highly effective methods of contraception …