Medically reviewed on September 10, 2018
(par a THYE roid HOR mone)
- Recombinant Human Parathyroid Hormone (1-84)
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Natpara: 25 mcg (1 ea); 50 mcg (1 ea); 75 mcg (1 ea); 100 mcg (1 ea) [contains metacresol]
Brand Names: U.S.
- Parathyroid Hormone Analog
Exogenous parathyroid hormone; parathyroid hormone raises serum calcium concentrations by increasing renal tubular calcium reabsorption, increasing intestinal calcium absorption, and by increasing bone turnover, which releases calcium into the circulation.
Vdss: 5.35 L
Primarily hepatic; cleavage by cathepsins
Renal (primarily by glomerular filtration)
Onset of Action
Peak effect: 10 to 12 hours
Time to Peak
5 to 30 minutes
Duration of Action
Special Populations: Renal Function Impairment
Mean Cmax in subjects with mild (CrCl 60 to 90 mL/minute) and moderate (CrCl 30 to 60 mL/minute) renal impairment was ~22% higher than that observed in subjects with normal renal function. AUC0-last and baseline-corrected AUC0-last was ~3.9% and ~2.5%, respectively, higher than that observed for subjects with normal renal function. No studies were conducted in patients with severe renal impairment or in patients on dialysis.
Special Populations: Hepatic Function Impairment
Mean Cmax and baseline-corrected Cmax values were 18% to 20% greater in the moderately impaired subjects than in those with normal function.
Use: Labeled Indications
Hypoparathyroidism: Adjunct to calcium and vitamin D to control hypocalcemia in patients with hypoparathyroidism
Limitations of use: Because of the potential risk of osteosarcoma, recommended only for patients who cannot be well-controlled on calcium supplements and active forms of vitamin D alone; has not been studied in patients with hypoparathyroidism caused by calcium-sensing receptor mutations or in patients with acute postsurgical hypoparathyroidism
There are no contraindications listed within the manufacturer's labeling.
Hypoparathyroidism: SubQ: Note: Prior to initiation of therapy, confirm that the serum calcium concentration is >7.5 mg/dL and the 25-hydroxyvitamin D stores are sufficient (correct if insufficient)
Initial: 50 mcg once daily.
Dosage adjustment: Note: Active forms of vitamin D and calcium supplementation may require adjustment during parathyroid hormone therapy based on albumin-corrected serum calcium concentrations; consult parathyroid hormone product labeling for more information.
Serum calcium (albumin-corrected) cannot be maintained >8 mg/dL without an active form of vitamin D and/or calcium supplementation: Increase the parathyroid hormone dose in increments of 25 mcg/day every 4 weeks; maximum daily dose: 100 mcg/day
Serum calcium (albumin-corrected) repeatedly >9 mg/dL after discontinuation of active forms of vitamin D and calcium supplementation decreased to a dose sufficient to meet daily needs: May decrease the parathyroid hormone dose to a minimum of 25 mcg/day
Maintenance: Use the lowest dose required to prevent both hypocalcemia and hypercalciuria while maintaining albumin-corrected serum calcium concentrations at the lower half of the normal range (ie, between 8 and 9 mg/dL) without the need for active forms of vitamin D and with calcium supplementation sufficient to meet the patient’s daily requirements.
Discontinuation or interruption of therapy: An abrupt interruption or discontinuation may result in severe hypocalcemia; resume treatment with or increase the dose of an active form of vitamin D and calcium supplementation (if indicated).
Missed dose: Administer parathyroid hormone as soon as reasonably feasible; additional calcium should be administered in the event of hypocalcemia.
Dosing should start at the lower end of dosing range and titrate to response due to possible increased incidence of hepatic, renal, or cardiac impairment.
Dosing: Renal Impairment
Mild to moderate impairment (CrCl ≥30 mL/minute): No dosage adjustment necessary.
Severe impairment (CrCl <30 mL/minute): There are no dosage adjustments provided in the manufacturer's labeling (has not been studied).
Dialysis: There are no dosage adjustments provided in the manufacturer's labeling (has not been studied).
Dosing: Hepatic Impairment
Mild to moderate impairment (Child-Pugh class A or B): No dosage adjustment necessary.
Severe impairment (Child-Pugh class C): There are no dosage adjustments provided in the manufacturer's labeling (has not been studied).
Reconstitute medication cartridge with provided mixing device. The mixing device can be used to reconstitute up to six medication cartridges.
SubQ: Administer subcutaneously into the thigh (alternate thighs each day) using the provided Q-Cliq pen. Follow instructions provided with the medication cartridges and the Q-Cliq pen to prepare the injection device for use. One Q-Cliq pen may be used for up to 2 years, with changing the reconstituted cartridge every 2 weeks. Patients and caregivers who will administer parathyroid hormone should receive appropriate training and instruction by a trained health care professional prior to first use.
Prior to reconstitution, the dual-chamber medication cartridge should be stored in the package provided at 2°C to 8°C (36°F to 46°F). After reconstitution, the medication cartridge should be stored in the Q-Cliq pen at 2°C to 8°C (36°F to 46°F) for up to 14 days. Store away from heat and light. Discard reconstituted medication cartridges after 14 days. Do not freeze or shake or use if it has been frozen or shaken. The mixing device and empty Q-Cliq pen can be stored at room temperature.
Alendronate: May diminish the therapeutic effect of Parathyroid Hormone. More specifically, Alendronate may interfere with normalization of blood calcium concentrations. Avoid combination
Cardiac Glycosides: Parathyroid Hormone may enhance the adverse/toxic effect of Cardiac Glycosides. More specifically, Parathyroid Hormone-related hypercalcemia may predispose to digitalis toxicity. Monitor therapy
Frequency not always defined.
Central nervous system: Paresthesia (31%), headache (25%), hypoesthesia (14%)
Endocrine & metabolic: Hypocalcemia (27%), hypercalcemia (19%)
Gastrointestinal: Diarrhea (12%), vomiting (12%)
Genitourinary: Hypercalciuria (11%)
Immunologic: Immunogenicity (6% to 16%; drug efficacy not affected)
Neuromuscular & skeletal: Arthralgia (11%)
1% to 10%:
Cardiovascular: Hypertension (6%)
Central nervous system: Peripheral pain (10%)
Endocrine & metabolic: Inhibited conversion of vitamin d3 to 25-hydroxy-d3 (6%)
Gastrointestinal: Upper abdominal pain (7%), facial numbness (6%)
Hematologic & oncologic: Osteosarcoma
Neuromuscular & skeletal: Neck pain (6%)
Respiratory: Upper respiratory tract infection (8%), sinusitis (7%)
Miscellaneous: Drug toxicity (risk when used concomitantly with digoxin and other drugs known to increase serum calcium)
Concerns related to adverse effects:
• Hypercalcemia: Severe hypercalcemia has been reported; the risk is highest during initiation of therapy and dose escalation. Monitor serum calcium concentrations and patients for signs and symptoms of hypercalcemia. Treat hypercalcemia as needed and consider temporary discontinuation or a reduction in dose if severe hypercalcemia occurs.
• Hypocalcemia: Severe hypocalcemia has been reported and can occur at any time during therapy; the risk is highest when a dose is missed or when parathyroid hormone therapy is withheld or abruptly discontinued. Monitor serum calcium concentrations and patients for signs and symptoms of hypocalcemia. In patients who must have therapy interrupted or discontinued, resume treatment with or increase the dose of an active form of vitamin D and/or calcium supplements to prevent severe hypocalcemia.
• Osteosarcoma: [US Boxed Warning]: In animal studies, parathyroid hormone has been associated with an increase in osteosarcoma; risk was dependent on both dose and duration. Avoid use in patients with an increased risk of osteosarcoma (including Paget disease, prior external beam or implant radiation therapy involving the skeleton, unexplained elevation of alkaline phosphatase, patients with open epiphyses, patients with hereditary disorders predisposing to osteosarcoma). Treatment should only be used in patients who cannot be well controlled on calcium supplements and active forms of vitamin D alone.
Concurrent drug therapy issues:
• Calcium supplementation: In patients receiving calcium supplementation, maintain the same dose of calcium at initiation of parathyroid hormone therapy. Calcium supplementation may require titration during parathyroid hormone therapy based on albumin-corrected serum calcium concentrations; consult parathyroid hormone product labeling for more information.
• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.
• Vitamin D: In patients receiving active forms of vitamin D, reduce the dose of active vitamin D by 50% at initiation of parathyroid hormone therapy if serum calcium is >7.5 mg/dL. Active forms of vitamin D may require titration during parathyroid hormone therapy based on albumin-corrected serum calcium concentrations; consult parathyroid hormone product labeling for more information.
Total serum calcium (albumin-corrected) prior to therapy initiation, within 3 to 7 days following initiation or dosage adjustments until maintenance dose has been achieved, and periodically thereafter; urinary calcium excretion (after maintenance dose is achieved); signs and symptoms of hypo- and hypercalcemia
Pregnancy Risk Factor
Adverse events were observed in animal reproduction studies.
• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
• Patient may experience diarrhea; joint pain; nausea; vomiting; neck pain; rhinitis; pharyngitis; abdominal pain; or tingling, tickling, or burning of skin. Have patient report immediately to prescriber signs of high calcium (weakness, confusion, feeling tired, headache, nausea and vomiting, constipation, or bone pain), skin growths, pain, severe dizziness, severe headache, or signs of low calcium (muscle cramps or spasms, numbness and tingling, or seizures) (HCAHPS).
• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.
Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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- Dosage Information
- Drug Interactions
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- En Español
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- Drug class: parathyroid hormone and analogs
Other brands: Natpara