New Osteoporosis Drug Gains FDA Approval
Teriparatide, which will be marketed as Forteo, is a recombinant protein whose amino acid sequence is identical to that of the biologically active region of the human parathyroid hormone. The product is the first FDA-approved drug that increases bone mass by stimulating the activity of bone-forming osteoblasts.
Yesterday's approval of teriparatide appears to have caught the company by surprise, and Lilly has not announced when it will supply the product to pharmacies. In a routine document filed with the Securities Exchange Commission two weeks ago, Lilly had estimated that FDA's approval of teriparatide would occur early next year.
The labeling (PDF) for teriparatide includes a boxed warning regarding the drug's ability to cause osteosarcoma in rats, a finding that may or may not have relevance in humans. Because of the possible cancer association, patients who are at risk of osteosarcoma, including people who have Paget's disease or who have received radiation therapy for bone cancer, should not use teriparatide.
Teriparatide is not indicated for the prevention of osteoporosis. The drug should be used only by patients whose osteoporosis puts them at high risk for bone fracture and in whom the benefits of treatment outweigh the risks. Pharmacists must include with each teriparatide supply dispensed to a patient the FDA-approved medication guide that describes the drug's risks.
The recommended dosage of teriparatide is 20 mcg administered subcutaneously into the thigh or abdomen once per day, preferably at the same time each day. Use of the drug for more than two years is not recommended.
According to the product's labeling, Forteo will be supplied in a pen-like drug delivery device containing 3.3 mL of a sterile solution of teriparatide 250 mcg/mL. Patients will self-inject the drug. Each activation of the device will automatically deliver 20 mcg of the drug, or 0.8 mL. [Correction: The volume of each 20-mcg dose is 0.08 mL.] The device must be stored at 28 degrees C at all times and can be used directly out of the refrigerator. Twenty-eight days after the first injection, the device must be discarded even if it is not empty.
Adverse events associated with the use of teriparatidechiefly leg cramps and dizzinessare described in the product's labeling as generally mild and not requiring the cessation of therapy.