RITOSA

What it is

RITOSA contains teriparatide 250 micrograms per millilitre solution for injection. Teriparatide is produced in E. coli using recombinant DNA technology and is identical to the 34-N-terminal amino acid sequence of endogenous human parathyroid hormone.

Approved indications

— Osteoporosis in postmenopausal women and primary osteoporosis in men when other agents are considered unsuitable and when there is a high risk of fractures. — Osteoporosis associated with sustained systemic glucocorticoid therapy in women and men at high risk for fracture.

Dosing overview

The recommended dose of RITOSA is 20 micrograms administered once daily by subcutaneous injection in the thigh or abdomen. Treatment with teriparatide is recommended for a lifetime duration of 24 months treatment. Calcium and vitamin D supplements are advised in patients with a low dietary intake of these nutrients.

Key safety warnings

In male and female rats, teriparatide caused an increase in the incidence of osteosarcoma (a malignant bone tumour) that was dependent on dose and treatment duration, with effects observed at systemic exposures ranging from 3 to 60 times the exposure in humans given a 20 micrograms dose. However, no increased risk was identified in a study in which 30 monkeys were treated with teriparatide for 18 months and then observed for a further 3 years, and post-marketing data in humans has not identified an increased risk. Patients should be made aware that teriparatide caused osteosarcoma in rats and that the clinical relevance of these findings is unknown. In normocalcaemic patients, slight and transient elevations of serum calcium concentrations have been observed following teriparatide injection, reaching a maximum between 4 and 6 hours and returning to baseline by 16 to 24 hours after each dose, and routine calcium monitoring during therapy is not required. Teriparatide has not been studied in patients with active urolithiasis and should be used with caution in patients with active or recent urolithiasis because of the potential to exacerbate this condition. In short-term clinical studies with teriparatide isolated episodes of transient orthostatic hypotension were observed, typically beginning within 4 hours of dosing and spontaneously resolving within a few minutes to a few hours, and when it occurred it happened within the first several doses, was relieved by placing subjects in a reclining position, and did not preclude continued treatment.

Contraindications

RITOSA should not be given to patients with hypersensitivity to teriparatide or to any of its excipients. RITOSA is contraindicated in pregnancy and breast-feeding, pre-existing hypercalcaemia, severe renal impairment, metabolic bone diseases (including hyperparathyroidism and Paget's disease of the bone) other than primary osteoporosis or glucocorticoid-induced osteoporosis, unexplained elevations of alkaline phosphatase, prior external beam or implant radiation therapy to the skeleton, and patients with skeletal malignancies or bone metastases.

PBS listing

RITOSA injection 250 micrograms per mL, 2.4 mL in multi-dose pre-filled cartridge is listed on the PBS with 2 items, streamlined restriction, and an ex-manufacturer price of A$149.55.

Regulatory history

RITOSA teriparatide 250 microgram/mL solution for injection pre-filled cartridge was first registered on the ARTG on 2 May 2024. In July 2025 the PBAC recommended RITOSA for severe established osteoporosis as a new generic brand under the same conditions as currently listed teriparatide.