Generic Fluoxetine a Big Hit With Drug Benefit Managers

Merck-Medco, the nation’s largest pharmacy benefits manager (PBM), has announced that last month’s launch of fluoxetine HCl by Barr Laboratories may have been the most successful debut of a generic medication to date.

“The rapid acceptance of the generic for Prozac is impressive,” Glen Stettin, M.D., vice president of clinical products at Merck-Medco, said in a written statement. “It represents a major step forward in balancing quality health care with cost-effectiveness.”

Preliminary figures show that Merck-Medco substituted the new generic in nearly 80 percent of prescriptions submitted by the PBM’s members for the brand name Prozac within the first week of the generic drug’s availability. The nation’s number-one PBM, a subsidiary of pharmaceutical powerhouse Merck and Co. Inc., provides pharmaceutical services to more than 65 million Americans, filling more than 450 million prescriptions last year.

Similar substitution figures were not available at press time from the nation’s leading retail pharmacies; however, cost comparisons between the Prozac brand and the generic version showed that the generic is selling at three leading national pharmacy chains at an average of a 20 percent savings to patients who must pay retail prices for their medications.

A 30-day supply of Prozac 20 mg Pulvules was selling for an average of $80.40 on August 23, whereas the generic was priced at $63.46. Patients who bought a 90-day supply on the same date paid an average of $220.91 for the brand or $179.60 for the generic, a savings of 23.4 percent. Similar cost savings were available for the 10 mg and 40 mg doses for both a 30-day and 90-day supply.

Eli Lilly and Company, the maker of Prozac, had no comment on the apparent immediate success of the generic’s launch. The company had waged a three-year battle to protect Prozac’s patent exclusivity from a claim by Barr that Lilly had filed additional applications for patents on Prozac simply to extend market exclusivity and that those additional patents should be ruled invalid.

Approved by the FDA in December 1987, Lilly enjoyed 14 years of market exclusivity with Prozac, ending with the expiration of the product’s original patent on February 2, 2001. Lilly was then granted a six-month extension of market protection through the Pediatric Exclusivity Rule.

The company had sought to extend patent protection further through applications for subsequent patents, which would have extended exclusivity until December 2003. Barr successfully argued that the subsequent patents on Prozac were not materially different from the original, and a U.S. Court of Appeals ruled the additional patents invalid in July. Lilly chose not to appeal the ruling to the U.S. Supreme Court. The generic version debuted on pharmacy shelves the second week of August.

In its annual report to shareholders, Lilly chief executive Sidney Taurel wrote that the company was “proud of Prozac,” noting that it had helped to “revolutionize the way mental illness is viewed and treated.” The company’s focus, he wrote, “is on the next Prozac—and the one after that.” ▪