Teriparatide

Products

Teriparatide is commercially available as a solution for injection in a prefilled injector (Forsteo, some countries also: Forteo). It was approved in the United States in 2002 and in the EU and many countries in 2003. The drug must be stored in a refrigerator and must not be frozen. Biosimilars are approved in many countries and also in many countries.

Structure and properties

Teriparatide is a recombinant polypeptide consisting of the first 34 amino acids of endogenous parathyroid hormone (1-34). It is the active fragment with a molecular mass of 4117.8 g/mol (4.1 kDa). Teriparatide is produced by biotechnological methods. Natural parathyroid hormone is produced by the parathyroid gland and consists of 84 amino acids. It has a central influence on calcium and phosphate balance.

Effects

Teriparatide (ATC H05AA02) has bone-building (anabolic) properties through direct stimulation of osteoblasts. This is in contrast to other drugs for the treatment of osteoporosis, which inhibit bone. The effects are similar to those of parathyroid hormone. Teriparatide increases absorption of calcium in the digestive tract and promotes calcium reabsorption at the kidney. Therapy increases bone mineral density and decreases fracture risk. The effects are due to binding to PTH (GPCR) receptors on the cell surface.

Indications

For the treatment of osteoporosis with a high risk of fractures:

  • In postmenopausal women with manifest osteoporosis and high risk of fracture.
  • In men with primary or hypogonadal osteoporosis at high risk of fracture.
  • Treatment of glucocorticoid-induced osteoporosis in adults at increased risk of fracture.

Off-label, teriparatide is also used to promote healing of fractures but does not have approval for this use.

Dosage

According to the SmPC. The drug is injected subcutaneously once daily into the thigh or abdominal skin. Patients perform the injection themselves after instruction by healthcare professionals. The first administrations should be done in a sitting or lying position. A therapy duration of two years has been studied and should not be exceeded. Subsequently, other osteoporosis medications may be administered. If the supply is inadequate, calcium and vitamin D should be supplemented.

Contraindications

Contraindications include (selection):

  • Hypersensitivity
  • Hypercalcemia
  • Severe impairment of renal function
  • Pregnancy, lactation
  • Previous radiotherapy
  • Children and adolescents

For complete precautions, see the drug label.

Interactions

Teriparatide should be combined with digoxin only with caution because increased adverse effects may occur in isolated cases.

Adverse effects

The most common possible adverse effects include pain, cramps in the legs or back, nausea, and injection site reactions. Serum calcium levels may be temporarily elevated. An increased incidence of malignant bone tumors, known as osteosarcomas, has been noted in experiments with rats. However, according to a long-term postmarketing study, there is no or only an extremely small risk for humans (e.g. Andrews et al., 2012).