Tolerance and efficacy of a low dose of the calcimimetic agent cinacalcet in controlling moderate to severe secondary hyperparathyroidism in hemodialysis patients.

Secondary hyperparathyroidism is almost a constant feature in chronic kidney disease (CKD) patients maintained on hemodialysis (HD). Calcimimetic agents appear to offer an alternative to surgery in controlling secondary hyperparathyroidism in these patients. Recent studies provide conflicting data on the benefits, efficacy and tolerance of cinacalcet as first-line therapy for the treatment of secondary hyperparathyroidism in CKD. This study was designed to investigate the efficacy and tolerance of a low dose of the calcimimetic agent cinacalcet in patients on long-term HD having moderate to severe secondary hyperparathyroidism. Twenty five adult male patients on HD for more than three years were included in the study. All had moderate to severe secondary hyperparathyroidism with serum intact parathyroid hormone (iPTH) >50 pmol/L, resistant to conventional treatment. We used the targets of Chronic Kidney Disease: Outcomes Quality Initiative (K/DOQI) clinical guidelines as optimal target of serum iPTH, calcium and phosphate. Patients were administered cinacalcet as a single oral daily dose of 30 mg and were followed-up for six months. Cinacalcet treatment for six months resulted in a significant reduction in the serum phosphate and iPTH levels while the serum calcium levels remained unchanged. Thirty-six percent of the patients attained the recommended serum iPTH levels, 40% achieved significant reduction of the serum iPTH levels and 24% showed no favorable response. Only one patient dropped out because of severe gastrointestinal symptoms. Our results suggest that treatment of CKD patients, having moderate to severe secondary hyperparathyroidism, with low-dose cinacalcet is effective and well tolerated.