Citing quality problems at two of Ranbaxy’s Indian manufacturing facilities, the FDA has revoked its tentative approvals for two of the company’s ANDAs, one for a generic of AstraZeneca blockbuster Nexium and the other for Hoffman-LaRoche AIDS drug Valycte.

The move to revoke the ANDAs will cost Ranbaxy the 180 days of exclusivity it won as first filer for Valcyte (valganciclovir HCl). It immediately clears the way for two generics of the drug to go to market since both Endo and Dr. Reddy’s have already won approval for their ANDAs.

The picture surrounding Nexium (esomeprazole magnesium) is less clear. At least eight companies in addition to Ranbaxy have filed ANDAs against Nexium, but none have been approved. Ranbaxy had tentatively won 180-day exclusivity as first-filer against Nexium 20 mg and 40 mg capsules, and the company declined to say whether it had forfeited that exclusivity.

In announcing the FDA’s decision earlier this month, Ranbaxy said the agency told the company it had revoked its approvals, first granted in 2008, because the facilities referenced in the ANDAs were not in compliance with GMP requirements. Ranbaxy acknowledged losing exclusivity on Valycte, but not Nexium. Ranbaxy last week sued the FDA, seeking a restraining order on approval of other ANDAs for the drug.

AstraZeneca said it assumes there will be no generic competition to Nexium in the U.S. this year.

The FDA’s decision is just the latest move in Ranbaxy’s long-running battle to bring its version of the blockbuster heartburn drug to market. Under a settlement with AstraZeneca, Ranbaxy said it should have been able to launch generic Nexium by as early as May.

A consent agreement between Ranbaxy and the FDA had given the company until Sept. 30 to reach certain quality milestones before it risked losing exclusivity.

Further adding to the drama has been an ongoing lawsuit that says the 2008 settlement agreement between AstraZeneca and Ranbaxy, as well as separate settlements with other ANDA filers, constituted an illegal pay-for-delay deal putting off generic Nexium.

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