parathyroid hormone: clinical use

Prescribing considerations

• The former licence was restricted to adjunctive treatment of adults with chronic hypoparathyroidism inadequately controlled by standard therapy.
• Treatment required supervision by clinicians experienced in hypoparathyroidism and careful coordination of calcium and vitamin D therapy.
• Do not initiate Natpar: manufacturing ceased and the UK marketing authorisation was withdrawn on 1 July 2026.
• Interruption or withdrawal can produce severe hypocalcaemia; arrange an alternative plan and close biochemical follow-up.

Contraindications and cautions

• Hypersensitivity to the active substance or excipients
• Current or previous skeletal radiation therapy
• Skeletal malignancy, bone metastases or increased baseline risk of osteosarcoma
• Unexplained elevation of bone-specific alkaline phosphatase
• Pseudohypoparathyroidism

Monitoring

• Serum calcium, particularly after starting, changing or interrupting treatment
• Symptoms of hypo- and hypercalcaemia
• Urinary calcium and renal function
• Phosphate, magnesium and vitamin D status where clinically relevant
• Calcium-sensitive concomitant medicines, particularly digitalis

Clinical pharmacology

Recombinant human parathyroid hormone comprises the full 84-amino-acid sequence. PTH1-receptor activation affects renal calcium and phosphate handling, vitamin D activation and bone turnover.

Formulation and product differences

• Natpar was supplied as powder and solvent mixed in a cartridge and administered with a reusable pen.
• Presentations differed by delivered strength.
• Mixed solution required refrigeration, protection from light and visual inspection before administration.

Injection

Route: Parenteral

Strengths: 50 micrograms/dose, 75 micrograms/dose