The initial dosage of IV paricalcitol for the prevention and treatment of secondary hyperparathyroidism in patients with chronic renal failure is 0.04-0.1 mcg/kg (2.8-7 mcg) at dialysis (no more frequently than every other day). Initial doses as high as 0.24 mcg/kg (16.8 mcg) have been used safely. Dosage of paricalcitol should be adjusted according the patient's PTH concentrations with the goal of reducing PTH concentrations to 1.5-3 times the upper limit of normal. If response is inadequate (i.e., in those patients whose PTH concentration increases, remains the same, or is not reduced by at least 30%), dosage of paricalcitol may be increased by 2-4 mcg per dose at 2- to 4-week intervals. Dosage of paricalcitol should be maintained in patients whose PTH concentrations have decreased by more than 30 to less than 60% of baseline values or in those with iPTH concentrations 1.5-3 times the upper limit of normal. Dosage of paricalcitol should be reduced as PTH concentrations decline in response to therapy; if PTH concentrations decrease by more than 60%, the dosage of paricalcitol should be reduced. If serum calcium concentrations are elevated, or the serum calcium times serum phosphorous (Ca x P) exceeds 75, dosage of paricalcitol should be reduced immediately or therapy withheld. Once these parameters have normalized, therapy can be reinitiated at a lower dosage. Dosage adjustment is not required in patients with mild to moderate hepatic impairment.
In the clinical studies used to establish safety and efficacy of paricalcitol, adults received an initial dosage of 0.04 mcg/kg given 3 times weekly; dose was then increased by 0.04 mcg/kg every 2 weeks until the iPTH concentrations were reduced by 30% or declined to less than 100 pg/mL, the fifth dose escalation reached 0.24 mcg/kg, the serum calcium times serum phosphorous (Ca x P) was more than 75 within any 2-week period, or serum calcium concentrations were greater than 11.5 mg/dL at any time. In these studies, dose of paricalcitol was reduced by 0.04 mcg/kg if iPTH concentrations decreased to less than 100 pg/mL, serum calcium concentrations were greater than 11.5 mg/dL, or serum calcium times serum phosphorus (Ca x P) exceeded 75. Dose of paricalcitol was maintained when PTH concentrations decreased by 30% or more (but remained above 100 pg/mL), serum calcium concentrations were less than 11.5 mg/dL, and the serum calcium times serum phosphorus product was acceptable (75 or less).
In a clinical study that evaluated the safety and efficacy of paricalcitol in children 5-19 years of age with end-stage renal disease (ESRD) on hemodialysis, pediatric patients with a baseline iPTH concentrations less than 500 pg/mL received an initial dosage of 0.04 mcg/kg administered 3 times weekly while those with a baseline iPTH concentrations of at least 500 pg/mL received an initial dosage of 0.08 mcg/kg administered 3 times weekly. The initial dose was then adjusted in increments of 0.04 mcg/kg based on serum concentrations of iPTH, calcium, and calcium times serum phosphorous (Ca x P) product. The mean dose in this study was 4.6 mcg (range: 0.8-9.6 mcg).