Parathyroid hormone, recombinant human (Natpara)

SELF-ADMINISTRATION - Subcutaneous injection

FDA Approved Indications:
  • Adjunct to calcium and vitamin D to control hypocalcemia in patients with hypoparathyroidism
Prior authorization criteria:
  • Patient is diagnosed with hypoparathyroidism, AND
  • Patient is 18 years of age or older, AND
  • Patient has hypocalcemia and has already started calcium and active vitamin D, AND
  • Patient's hypocalcemia is not well-controlled on calcium and active vitamin D alone
  • Vitamin D stores are sufficient and serum calcium is above 7.5mg/dL before starting Natpara
  • Avoid in patients with an increased risk for osteosarcoma (e.g., patients with Paget's disease of bone or unexplained elevations of alkaline phosphatase, pediatric and young adult patients with open epiphyses, patients with hereditary disorders predisposing to osteosarcoma, or patients with a prior history of external beam or implant radition therapy involving the skeleton)
  • In patients using Natpara concomitantly with digoxin: hypercalcemia can increase the risk of digoxin toxicity; monitor serum calcium more frequently and increase monitoring when initiation or adjusting Natpara dose
Dosing:
  • Initial: 50 mcg injected once daily in the thigh.  When starting Natpara, decrease dose of active viatmin D by 50%, if serum calcium is above 7.5mg/dL
  • Monitor serum calcium levels every 3 to 7 days after starting or adjusting Natpara dose and when adjusting either active vitamin D or calcium supplements dose while using Natpara
  • The recommended dose of Natpara is the minimum dose required to prevent both hypocalcemia and hypercalciuria (generally the dose that maintains total serum calcium (albumin-corrected) within the lower half of the normal range (i.e., between 8 and 9 mg/dL)
  • Natpara may be increased in increments of 25 mcg every 4 weeks up to a maximum daily dose of 100 mcg if serum calcium cannot be maintained above 8 mg/dL without an active form of vitamin D and/or oral calcium supplementation
  • Natpara may be decreased to as low as 25mcg per day if total serum calcium is repeatedly above 9 mg/dL after the active form of vitamin D has been discontinued and calcium supplement has been decreased to a dose sufficient to meet daily requirements