PARICALCITOL COMPARED TO CINACALCET WITH LOW-DOSE VITAMIN D THERAPY FOR THE TREATMENT OF SECONDARY HYPERPARATHYROIDISM IN PATIENTS RECEIVING HAEMODIALYSIS: RESULTS OF THE IMPACT SHPT RESEARCH

INTRODUCTION. Optimal treatment for secondary hyperparathyroidism (SHPT) is not defined nowadays. The IMPACT SHPT (ClinicalTrials.gov identifier: NCT00977080) research compared 2 treatment regimens of SHPT for intact parathyroid hormone (iPTH) level control in patients receiving haemodialysis: 1) therapy based on dose-titrated paricalcitol with cinacalcet (only for hypercalcaemia); 2) therapy based on coombination of cinacalcet with low-dose vitamin D. PATIENTS AND METHODS. In this 28-week, multicentre, open-label Phase 4 study, participants were randomly selected to receive paricalcitol or cinacalcet with low-dose vitamin D. Randomization and analysis were stratified by paricalcitol injection method [intravenous (IV) or oral]. The primary efficacy end point was the proportion of subjects who achieved medium iPTH level of 150-300 pg/mL during Weeks 21–28. RESULTS. Of 272 subjects of randomized research, 268 received one or more dose of study drug. 101 patients from group with IV injection and 110 from group of oral administration with one or more values during Weeks 21-28 were included in the primary analysis. In IV injection, 57.7% of subjects in the paricalcitol group versus 32.7% in the cinacalcet group (P = 0.016) achieved the primary end point. In the oral administration group, the corresponding proportions of subjects were 54.4% for paricalcitol treatment and 43.4% for cinacalcet therapy (P = 0.260). Cochran-Mantel-Haenszel test, controlling for stratum, revealed overall superiority of paricalcitol (56.0%) over cinacalcet (38.2%; P = 0.010) in achieving iPTH 150-300 pg/mL during Weeks 21-28. Hypercalcaemia occurred in 4 (7.7%) and 0 (0%) of paricalcitol-treated subjects in the IV and oral administration, respectively. Hypocalcaemia occurred in 46.9% and 54.7% of cinacalcet-treated subjects in the IV and oral administration, respectively. CONCLUSION. Paricalcitol versus cinacalcet with low-dose vitamin D provided superior control of iPTH, with low incidence of hypercalcaemia.

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