FDA approves first generic 5-HT-3 antagonist

The Food & Drug Administration has approved ondansetron injection, USP (TEVA-SICOR Pharmaceuticals). The pro- product, AP-rated and equivalent to GlaxoSmithKline's Zofran, is the first generic 5-hydroxytryptamine-3 (5-HT-3) receptor antagonist to receive FDA approval. It is indicated for the prevention of chemotherapy-induced nausea and vomiting (CINV) and the prevention of postoperative nausea and vomiting (PONV).

"GlaxoSmithKline was the innovator. Through an agreement we had with Glaxo, we were able to get to market a month prior to the expiration of its pediatric exclusivity period on Dec. 22," explained Jeffrey Herzfeld, Pharm.D., senior VP and general manager of TEVA-SICOR. "Although ondansetron is approved for the prevention of CINV and in helping manage the side effects of emetogenic chemotherapy, the majority of sales are for PONV. But with a low-cost generic equivalent available, we anticipate the use of our product for the prevention of CINV .... For the most part, 5-HT-3 receptor antagonists are considered clinically interchangeable," he said, "with the exception of palonosetron (Aloxi, MGI Pharma), which has a longer half-life."

In addition to these new injectable options, Par Pharmaceutical's subsidiary Kali Laboratories received permission to market ondansetron orally disintegrating tablets (ODTs) in 4-mg and 8 mg-strengths with 180-day market exclusivity. The company expects to launch its product early this year.

Jorgenson pointed out that Zofran and other 5-HT-3 receptor antagonists make up a significant portion of many institutions' drug budgets. Zofran was the 20th most expensive brand-name drug used in U.S. hos-pitals in 2005, with total costs of $839.26 million. Jorgenson said that initial estimates of the cost savings gained by switching to the generic product pegged the price of a 4-mg dose to drop from $16 to $3. It will be interesting to see if generics capture the majority of the 5-HT-3 receptor antagonist market, he concluded.

THE AUTHOR is a clinical writer based in New Jersey.