Secondary hyperparathyroidism or hypocalcemia:
Indications for: NATPARA
Adjunct to calcium and vitamin D to control hypocalcemia in hypoparathyroidism.
Limitations of Use:
Use only for patients uncontrolled on calcium supplements and active vitamin D alone. Not studied in hypoparathyroidism caused by calcium-sensing receptor mutations or in acute post-surgical hypoparathyroidism.
Individualize based on total serum calcium (albumin-corrected) and 24hr urinary calcium excretion. Give as SC inj in the thigh (alternate thigh daily). Initially 50mcg once daily; may increase in increments of 25mcg every 4 weeks up to max 100mcg daily, if serum calcium is not maintained >8mg/dL. May decrease to 25mcg daily if serum calcium repeatedly >9mg/dL. If currently receiving active vitamin D: decrease vitamin D dose by 50% if serum calcium >7.5mg/dL. Maintenance: use lowest dose to achieve total serum calcium within the lower half of the normal range (approx. 8–9mg/dL). See full labeling.
<18yrs: not established.
Potential risk of osteosarcoma.
Confirm sufficient 25-hydroxyvitamin D stores and serum calcium >7.5mg/dL prior to initiation. Avoid in those with increased risk of osteosarcoma (eg, Paget's disease of bone, unexplained elevations of alkaline phosphatase, pediatric and young adults with open epiphyses, hereditary disorders predisposing to osteosarcoma, history of external beam or implant radiation therapy involving the skeleton). Measure calcium concentration every 3–7 days after starting therapy and when adjusting Natpara, active vitamin D, or calcium supplement doses; consider holding and/or reducing dose if severe hypercalcemia occurs. Monitor for severe hypocalcemia when Natpara interruption or discontinuation; resume treatment with or increase dose of vitamin D and/or calcium supplements if occurs. Renal impairment. Elderly. Pregnancy. Nursing mothers: monitor infants.
Concomitant alendronate: not recommended. Concomitant digoxin: monitor serum calcium, digoxin levels, and for digitalis toxicity; adjustments may be needed for both drugs.
Paresthesia, hypocalcemia, headache, hypercalcemia, nausea, hypoaesthesia, diarrhea, vomiting, arthralgia, hypercalciuria, pain in extremity; hypersensitivity reactions (discontinue if occur), possibly osteosarcoma.
Generic Drug Availability:
Multi-dose cartridges (dual-chamber)—2