Aims Methods SNF472 is a calcification inhibitor being developed for the treatment of cardiovascular calcification in haemodialysis (HD) and in calciphylaxis patients. This study investigated the safety, tolerability and pharmacokinetics (PK) of intravenous (IV) SNF472 in healthy volunteers (HV) and HD patients. This is a first-time-in-human, double-blind, randomized, placebo-controlled Phase I study to assess the safety, tolerability and PK of SNF472 after ascending single IV doses in HV and a single IV dose in HD patients. A pharmacodynamic analysis was performed to assess the capability of IV SNF472 to inhibit hydroxyapatite formation. Results Conclusion Twenty HV and eight HD patients were enrolled. The starting dose in HV was 0.5 mg kg(-1) and the dose ascended to 12.5 mg kg(-1). The dose selected for HD patients was 9 mg kg(-1). Safety analyses support the safety and tolerability of IV SNF472 in HD patients and HV. Most treatment-emergent adverse events were mild in intensity. No clinically significant effects were observed on vital signs or laboratory tests. PK results were similar in HD patients and HV and indicate a lack of significant dialysability. Pharmacodynamic analyses demonstrated that SNF472 administration reduced hydroxyapatite crystallization potential in HD patients who received IV SNF472 9 mg kg(-1) by 80.0 +/- 2.4% (mean +/- standard error of the mean, 95% CI, 75.3-84.8) compared to placebo (8.7 +/- 21.0%, P < 0.001, 95% CI, -32.4 to 49.7). The results from this study showed acceptable safety and tolerability, and lack of significant dialysability of IV SNF472. It is a potential novel treatment for cardiovascular calcification in end-stage renal disease and calciphylaxis warranting further human studies.