Abstract: 【Abstract】Objective The objective of this study was to examine efficacy and safety of two dosing regimens of selective vitamin D receptor activator paricalcitol for the treatment of secondary hyperparathyroidism (SHPT) in maintenance hemodialysis (MHD) patients. Methods This retrospective study recruited 32 MHD patients with SHPT. Patients were randomized to two treatment arms by initial dose of paricalcitol package insert (PI): US group (initial dose 0.04 μg/kg) and EU group (initial dose iPTH (pg/mL)/80μg). After a wash out period of 2- 4 weeks, they received initial dose of US or EU regimen three times weekly for 12 weeks and one month follow-up after drug withdrawal. The dose of paricalcitol was adjusted biweekly according to serum iPTH, calcium (Ca) and phosphorus (P) levels in the monitoring weeks. The efficacy and safety of paricalcitol were evaluated between the two groups by comparison of the primary endpoint (iPTH reduced by ≥ 30% of baseline in two consecutive assays) and the tendency to adverse effects including hypercalcemia, hyperphosphatemia, elevated Ca-P product, hypoparathyroidism and drug suspension. Results The effective rate was similar (88.2% vs. 73.3%, P＞0.05), and no inferiority was demonstrated between the two groups. In the prior 6 weeks in EU group with relatively higher initial dose of paricalcitol, patients were more likely to have adverse events and withdrawal due to adverse events than the patients in US group; hypercalcemia was 47.1% and 42.2% (P＜0.05), elevated Ca-P product was 58.5% and 37.8% (P＜0.05), in EU group and US group, respectively. In the posterior 6 weeks in US group with increasing cumulative dose of paricalcitol, patients were more likely to have adverse events and withdrawal due to adverse events than the patients in EU group; hypercalcemia was 44.4% and 27.5% (P＜0.05), elevated Ca-P product was 60.0% and 35.3% (P＜ 0.05), in US group and EU group, respectively. Conclusions Both EU and US PI paricalcitol dosing strategies effectively reduced iPTH level in Chinese subjects with SHPT with minimal impact on serum Ca and P levels, but patients with higher dose of paricalcitol had increased possibility of dose adjustment and drug withdrawal due to adverse events including hypercalcemia, hyperphosphatemia, elevated Ca-P product and hypoparathyroidism.
To get the best clinical benefits of paricalcitol, different initial dose and personalized regimen are required.

Key words: paricalcitol, secondary hyperparathyroidism, regimens