Parathyroid Hormone Dosage

Usual Adult Dose for Hypocalcemia

Prior to initiating therapy:

• Confirm 25-hydroxyvitamin D stores are sufficient; if not, correct insufficiency per standard of care
• Confirm serum calcium is above 7.5 mg/dL

INITIAL dose: 50 mcg subcutaneously once a day

• For patients using active forms of vitamin D: Decrease active vitamin D dose by 50% if serum calcium is above 7.5 mg/dL
• Maintain calcium supplement doses in those using calcium supplements
• Measure serum calcium concentration within 3 to 7 days
• Adjust active vitamin D dose or calcium supplement dose, or both based on serum calcium value and clinical assessment (see dosage adjustment section)

ADJUST dose in increments of 25 mcg every 4 weeks if serum calcium cannot be maintained above 8 mg/dL without an active form of vitamin D and/or calcium supplementation
MAINTENANCE dose: 25 to 100 mcg subcutaneously once a day

Comments:

• Dose should be individualized based on total serum calcium (albumin-corrected) and 24-hour urinary calcium excretion; maintenance dose is the minimum dose required to achieve serum calcium within the lower half of the normal range without the need for active forms of vitamin D and with calcium supplementation sufficient to meet the patient's daily requirements.
• With each dose change, monitor clinical response and serum calcium; adjust active vitamin D and calcium supplementation as needed (see dosage adjustment section).
• Due to potential risk of osteosarcoma, use should be reserved for those who cannot be well-controlled on calcium supplements and active forms of vitamin D alone.

Use: An adjunct to calcium and vitamin D to control hypocalcemia in patients with hypoparathyroidism.

Renal Dose Adjustments

Mild to moderate renal impairment: No adjustment recommended
Severe renal impairment: Data not available

Liver Dose Adjustments

Mild to moderate hepatic impairment: No adjustment recommended
Severe hepatic impairment: Data not available

Dose Adjustments

Elderly: Use with caution; consider starting at the lower end of the dosing range

Doses Adjustments for Active Forms of Vitamin D and Calcium Supplements:
Serum Calcium Above the Upper Limit of Normal (10.6 mg/dL):

• First Adjustment: Decrease OR discontinue active vitamin D forms (for patients receiving the lowest available dose)
• Second Adjustment: Decrease calcium supplementation

Serum Calcium Greater than 9 mg/dL but below 10.6 mg/dL:

• First Adjustment: Decrease OR discontinue active vitamin D forms (for patients receiving the lowest available dose)
• Second Adjustment: No change in calcium supplementation OR decrease calcium supplementation if active vitamin D has been discontinued

Serum Calcium less than or equal to 9 mg/dL but above 8 mg/dL:

• First Adjustment: No change
• Second Adjustment: No change

Serum Calcium lower than 8 mg/dL:

• First Adjustment: Increase active vitamin D
• Second Adjustment: Increase calcium supplementation

Continue to adjust doses as above until target serum calcium is within the lower half of the normal range, active vitamin D is discontinued, and calcium supplementation is sufficient to meet daily requirements

Interruption or Discontinuation of Therapy:

• Abrupt interruption or discontinuation may result in severe hypocalcemia
• Upon temporary or permanent discontinuation of this drug, monitor serum calcium and increase exogenous calcium and/or vitamin D as needed.

Precautions

The US FDA requires a Risk Evaluation and Mitigation Strategy (REMS) for parathyroid hormone. It includes elements to assure safe use, and an implementation system. For additional information: www.fda.gov/REMS.

US BOXED WARNINGS: POTENTIAL RISK OF OSTEOSARCOMA

• In male and female rats, parathyroid hormone caused an increase in the incidence of osteosarcoma (a malignant bone tumor). The occurrence of osteosarcoma was dependent on parathyroid hormone dose and treatment duration. This effect was observed at parathyroid hormone exposure levels ranging from 3 to 71 times the exposure levels in humans receiving a 100 mcg dose. These data could not exclude a risk to humans.
• Because of a potential risk of osteosarcoma, use this drug only in patients who cannot be well controlled on calcium and active forms of vitamin D alone and for whom the potential benefits outweigh this potential risk.
• Avoid use in patients who are at increased baseline risk for osteosarcoma such as 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 radiation therapy involving the skeleton.
• Because of the risk of osteosarcoma, this drug is available only through a restricted program under a Risk Evaluation and Mitigation Strategy (REMS) called the NATPARA REMS Program.

CONTRAINDICATIONS:

• Hypersensitivity to the active substance or any of the product excipients; anaphylaxis, angioedema, and urticaria have occurred

Safety and efficacy have not been established in patients younger than 18 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration advice:

• Administer subcutaneously once a day in the thigh; rotate sites injecting into alternate thighs
• Patients should receive appropriate training and instruction by a trained healthcare professional prior to use
• Patients should be instructed not to reuse or share devices; patients should be instructed in safe disposal procedures

Missed dose: If a dose is missed, administer as soon as possible; additional calcium may be needed

Storage requirements:

• Prior to Use: Dual chamber medication cartridge should be stored in refrigerator (36F to 46F [2C to 8C]) in original package
• In Use: Reconstituted medication cartridge should be stored in refrigerator (36F to 46F [2C to 8C]) in the Q-Cliq pen, away from heat and light; may be used for up to 14 days; discard medication cartridges after 14 days
• Do not freeze or shake medication cartridges; discard if frozen or shaken
• Mixing device and empty Q-Cliq pen may be stored at room temperature

Reconstitution/preparation techniques:

• Each medication cartridge is designed to deliver 14 doses
• Mixing device (which is provided in a separate carton) is designed to enable reconstitution; each mixing device can be used to reconstitute up to 6 medication cartridges
• The Q-Cliq pen can be used for up to 2 years when used with cartridges that have been reconstituted every 14 days
• Consult Instructions for Use in the product labeling for complete instructions

General:

• This drug is available through a REMS program to mitigate the potential risk of osteosarcoma associated with use.
• This drug has not been studied in patients with hypoparathyroidism caused by calcium-sensing receptor mutations.
• The drug has not been studied in patients with acute post-surgical hypoparathyroidism.

Monitoring:

• Serum calcium levels should be monitored after starting or adjusting doses, when interrupting or discontinuing therapy, when making changes to co-administered drugs known to raise serum calcium levels, and in patients concomitantly receiving digoxin
• Monitor for signs and symptoms of hypocalcemia and hypercalcemia

Patient advice:

• Patients should be instructed to read the US FDA-approved patient labeling (Medication Guide and Instructions for Use).
• Patients should be instructed to promptly report signs and symptoms of possible osteosarcoma such as persistent localized pain or a new soft tissue mass that is tender to palpitation.
• Patients should be instructed to promptly report signs or symptoms of high or low calcium.
• Patient should be instructed not to abruptly stop this medication without talking with their healthcare provider; they should inform their healthcare provider of any changes to their medication regimen.

See also:

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer