Generics line up waiting for big-name patents to expire

Close to $63 billion worth of branded drugs are set to lose their patents between 2007 and 2012, paving the way for generic replicas. This year, to date, the biggest drug to lose its patent has been Sanofi-Aventis’ $2.2-billion sleep medication, Ambien.

This spawned the approval of 13 generic equivalents of zolpidem tartrate within two days, under a cluster approval, a process that now is being adopted by the Food and Drug Administration to quickly bring more drugs to market. (Sanofi-Aventis’ extended-release Ambien CR isn’t available in generic versions.) Generics approvals were given to companies including Teva, Mylan, Dr. Reddy’s and Watson. Prasco has released an authorized generic.

Another cluster approval this year was awarded for generic Lamisil tablets (terbinafine hydrochloride). The FDA approved products from companies including Apotex, Aurobindo Pharma, Dr. Reddy’s, Glenmark and Wockhardt. This antifungal medication from Novartis saw annual U.S. sales of approximately $687 million for the 12 months ended March 2007, according to IMS Health data.

At the end of last year, the FDA approved the first generic versions of GlaxoSmithKline’s Wellbutrin XL (bupropion hydrochloride) extendedrelease tablets, which are indicated for the treatment of major depressive disorder. Wellbutrin XL was the 21st highest-selling brand name drug in the United States in 2005, with sales totaling $1.3 billion, and Anchen Pharmaceuticals was first to market with the generic product, for which it received 180 days of marketing exclusivity. There are now generics available from Watson and Teva.

Also toward the end of 2006, Pfizer lost patent protection on Norvasc, the world’s most-prescribed branded medicine for treating hypertension. The FDA approved generic amlodipine besylate 2.5 mg, 5 mg and 10 mg tablets from Mylan, giving the generic drug maker 180 days of exclusivity on the market. This period now has expired, and other generics are on the market from companies including Teva, Ranbaxy and Roxane Laboratories.

Still to come this year is a generic version of Schering-Plough’s Clarinex. This drug was launched in 2002 when Schering-Plough lost its patent on the antihistamine blockbuster Claritin. Clarinex is, essentially, a tweaked version of its predecessor, and sales have been disappointing: $722 million in 2006, a fraction of the $3 billion a year the drug maker saw for Claritin. Clarinex loses its patent on Oct. 1.

Migraine medication Imitrex from GSK lost its patent in June. GSK has granted Dr. Reddy’s authorized generic status for sumatriptan succinate, which is expected to launch at the end of next year.

Meridian from Abbott Labs loses its patent protection on Dec. 11. This obesity drug had global sales of $345 million worldwide last year, $60 million of which originated in the United States. Generic versions of this drug may not be as attractive to manufacturers since the launch this year of FDA-approved OTC product Alli from GSK.

Pfizer’s antihistamine Zyrtec loses patent protection on Dec. 25. The FDA has granted tentative approval to an abbreviated new drug application from Caraco for cetirizine hydrochloride, 5 mg and 10 mg immediate release tablets. Zyrtec had U.S. sales of approximately $1.21 billion for the 12-month period ended Dec. 31, 2006, according to IMS Health data.

The last patent expiration of this year looks likely to be schizophrenia medication Risperdal from Janssen Pharma, which had annual sales of $4 billion.

Moving into 2008, branded drug patents will be falling by the wayside. Depakote (Abbott), Fosamax (Merck), Advair (GSK), Serevent (GSK), Effexor XR (Wyeth), Lamictal (GSK) and Topamax (Ortho McNeil) are all expected to go head-to-head with generic competition.