UPDATED: After a 6-year delay, Medicines Co. bags FDA approval for once-troubled antibiotic

More than 5 years after The Medicines Company ($MDCO) bagged Targanta and its troubled antibiotic oritavancin for the bargain basement rate of $42 million plus potential milestone payments, the biotech has finally nailed down an elusive FDA approval of the product for skin infections caused by Gram-positive bacteria, including MRSA. And the approval came through with the agency's blessing to deliver the antibiotic in a single infusion, which may  well burnish its market potential.

The Medicines Company says that the antibiotic, which will be sold as Orbactiv, is the only antibiotic approved for acute bacterial skin and skin structure infections with a once-only administration, an objective which figured prominently in its buyout deal with Targanta. Easier dosing should put a lighter strain on patients fighting off one of these dangerous infections. 

A spokesman for The Medicines Company told FierceBiotech Thursday that the Parsipanny, NJ-based company  is no longer on the hook for an added $1.20 a share bonus--or about $25 million--outlined in the original buyout deal for that green light from regulators in the U.S.

"Under the agreement between The Medicines Company and Targanta, certain approval milestones in the U.S. and EU needed to occur prior to December 31, 2013," noted the spokesperson. "As these milestones were not achieved by the specified date," The Medicines Company is no longer obligated to pay former Targanta shareholders the added bonus.

"However, The Medicines Company remains obligated to former Targanta shareholders for $49.4 million should aggregate net sales of Orbactiv reach or exceed $400 million in four consecutive calendar quarters ending on or before the end of 2021," he added. "The company is also obligated for $40 million in additional payments to other unnamed third parties."

The EMA, meanwhile, is expected to make its ruling in the first half of 2015, 6 years after the company scrapped the original application.

The FDA's approval underscores the challenges as well as the potential when small biotechs set out to develop an antibiotic. The FDA rejected Targanta's petition for the antibiotic all the way back in 2008, demanding another trial with more MRSA patients and forcing then-CEO Mark Leuchtenberger to lay off 75% of the staff. Instead of pursuing a new study, though, the board opted for the sale and passed the ball to The Medicines Company.

Targanta investors have  so far regained only a portion of the money they put into the company. In the third round alone back in 2007 venture groups bet $70 million on oritavancin's late-stage program. In biotech, you can lose money even when you're right about a program's potential.

"Orbactiv given as a single dose treatment is a welcome new development for the treatment of skin infections," said G. Ralph Corey, a professor of medicine and infectious diseases at Duke University, in a statement. "With a single dose treatment regimen Orbactiv may help reduce the dosing burden seen with antibiotics given as multiple intravenous administrations to patients with these infections."  

- here's the release