Jane S. Ricciuti, RPh, MS

Disclosures

December 27, 2002

In This Article

Osteoporosis Agents

Forteo
(teriparatide [rDNA origin]) Injection

Manufacturer: Eli Lilly and Company

Drug Approval Classification: Original New Drug Application (Approval Date: 11/26/02)

Indication: Forteo (teriparatide [rDNA origin]) injection is indicated for the treatment of postmenopausal women with osteoporosis who are at high risk for fracture. These include women with a history of osteoporotic fracture, or who have multiple risk factors for fracture, or who have failed or are intolerant of previous osteoporosis therapy, based on physician assessment. In postmenopausal women with osteoporosis, Forteo increases bone mineral density (BMD) and reduces the risk of vertebral and nonvertebral fractures.

Forteo is indicated for increasing bone mass in men with primary or hypogonadal osteoporosis who are at high risk for fracture. These include men with a history of osteoporotic fracture, or who have multiple risk factors for fracture, or who have failed or are intolerant to previous osteoporosis therapy, based on physician assessment. In men with primary or hypogonadal osteoporosis, Forteo increases BMD. The effects of Forteo on risk for fracture in men have not been studied.

Dosing: Forteo should be administered 20 mcg subcutaneously once daily into the thigh or abdominal wall. Upon initiation of treatment, it is recommended that the patient be observed for signs and symptoms of orthostatic hypotension.

Forteo is a clear and colorless liquid available in a 750 mcg/3 mL prefilled pen delivery device that should be stored under refrigeration.

The safety and efficacy of Forteo have not been evaluated beyond 2 years of treatment.

Clinical Summary: Forteo (teriparatide [rDNA origin] injection) contains recombinant human parathyroid hormone (1-34) [rhPTH(1-34)], which has an identical sequence to the 34 N-terminal amino acids (the biologically active region) of the 84-amino acid human parathyroid hormone (PTH). The mechanism of action of Forteo is through PTH regulation. Teriparatide affects calcium and phosphorus metabolism in a pattern consistent with the known actions of endogenous PTH (eg, increases serum calcium and decreases serum phosphorus).

More than 2800 patients were assessed for the safety and efficacy of Forteo in 24 clinical trials. A study by Neer and colleagues[1] demonstrated increased new bone formation, lowered risk of vertebral fractures, and increased BMD in postmenopausal women with osteoporosis. All women received 1000 mg of calcium per day and at least 400 IU of vitamin D per day.

New vertebral fractures decreased from 14.3% in the placebo group to 5% in the Forteo group.

  • New nonvertebral osteoporotic fractures decreased from 5.5% in the placebo group to 2.6% in the Forteo group.

  • Lumbar BMD increased in postmenopausal women with osteoporosis over the course of 18 months up to 12%; the placebo group showed no clinically significant change in BMD.

  • In a clinical study of men with idiopathic or hypogonadal osteoporosis, Forteo increased BMD during 10 months of average treatment compared with placebo -- 94% of men had an increase in their spine BMD; 53% of men taking Forteo had an increase of spine BMD ≥ 5% compared with 10% of men in the placebo group.

    Adverse Effects: The labeling for Forteo notes that in preclinical trials (on rats), there was an increase in the incidence of osteosarcoma related to dose and treatment duration. Doses used in preclinical studies were 3 to 60 times the exposure in humans.

    Adverse events with Forteo were similar to those with placebo; the most common included: dizziness, depression, insomnia, vertigo, rhinitis, increased cough, arthralgia, leg cramps, nausea, and asthenia.

    Pharmacokinetics: The half-life of teriparatide in serum is approximately 1 hour when administered by subcutaneous injection. No metabolism or excretion studies have been performed with teriparatide. Peripheral metabolism of PTH is believed to occur by nonspecific enzymatic mechanisms in the liver followed by excretion via the kidneys.

    No clinically relevant drug interactions were identified with Forteo.

    References

    Forteo (teriparatide [rDNA origin]) Injection labeling

    Neer RM, Arnaud CD, Zanchetta JR, et al. Effect of parathyroid hormone (1-34) on fractures and bone mineral density in postmenopausal women with osteoporosis. N Engl J Med. 2001;344:1434-1441. Abstract

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