Hikma Pharmaceuticals plc (HKMPY)  shares fell sharply again in London Friday after the generic drugmaker lowered its full year revenue guidance Friday after the U.S. Food & Drug Administration expressed concern over its generic Advair Diskus product.

Hikma said it expects revenues for its current fiscal year to come in at between $2 billion and $2.1 billion, down from the $2.2 billion forecast it published in its recent annual report last month. Revenues from its generics business, Hikma said, are likely to be in the $670 million range, down from a previous forecast of $800 million.

"This updated guidance reflects changes in the outlook for our Generics business, where we have revised our expectation for the launch timing of our generic version of Advair Diskus and where we are experiencing increased price erosion on our marketed products," the company said in .

"We maintain our full year guidance for our Injectables and Branded businesses," Hikma added in its regular investor update.

Hikma fell as much as 7% in the opening minutes of trading before paring the decline to around 5% by 08:30 BST, extending their month-to-date decline past 17% and changing hands at 1,615 pence each.

Hikma said on May 11 that it had received a 'complete response letter' from the FDA and that, as a result, it now sees a "low likelihood of approval this year" for Advair Diskus.

"Hikma is committed to bringing this important product to the US market and will work collaboratively with the FDA to address their outstanding questions," the company said in a statement at the time.

Advair is a blockbuster asthma treatment pioneered by Glaxo (GSK - Get Report) although it lost the patent in 2010 and has since been bracing for a flood of generics to hit the market.

Hikma hasn't said it will not be able to launch Advair this year however, Barclays analysts have said that the chances of its being released in 2017 are near to zero. Vane-Tempest has said that Hikma's Advair is unlikely to appear in pharmacies before the second half of 2018.