FDA Approves 6-Month Formulation of Triptorelin for Prostate Cancer

Yael Waknine

March 15, 2010

March 15, 2010 — The US Food and Drug Administration (FDA) has approved a twice-yearly 22.5-mg formulation of triptorelin pamoate injection (Trelstar, Watson Pharmaceuticals, Inc) for the palliative treatment of advanced prostate cancer.

With anticipated availability in May 2010, the long-acting product is the first and only 6-month intramuscular gonadotropin-releasing hormone agonist to be approved by the FDA. It also offers added convenience in the form of room-temperature storage and administration via the Mixject system's thin 21-gauge needle, which decreases the risk for injection-site pain — reported by only 1.7% of patients in the trial.

FDA approval of the 22.5-mg formulation of triptorelin was based on data from a 48-week, phase 3 clinical trial showing that treatment yielded a mean testosterone serum level of 12.8 ng/dL, well below castration levels associated with androgen deprivation therapy.

By day 29, 97.5% of clinical trial patients achieved castrate level, and more than 98% were below castrate level at 6 and 12 months. In addition, median prostate specific antigen levels were decreased by 96.4% at study end.

"We are confident that the unique combination of convenience, reliable testosterone and [prostate specific antigen] suppression, and injection site tolerability of this longer-acting TRELSTAR® formulation will provide advanced prostate cancer patients and their physicians an important treatment option," said Fred Wilkinson, executive vice president, Global Brands at Watson, in a company news release.

Adverse events most commonly reported in the study included hot flushes (71.7%), erectile dysfunction (10.0%), and testicular atrophy (7.5%).

Triptorelin pamoate previously was approved in 1-month (3.75 mg) and 3-month (11.25 mg) formulations.


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