AstraZeneca potassium drug finally approved, threatening Vifor

LONDON, May 21 (Reuters) - The decision by U.S. regulators to finally approve AstraZeneca (NYSE: AZN - news) 's much-delayed excess potassium drug Lokelma gives the group another new medicine launch, boosting its portfolio as it strives to offset declining sales of older products.

The U.S. Food and Drug Administration (FDA) had turned down the drug, formerly known as ZS-9, two times previously, casting doubt over AstraZeneca's decision to buy its original developer ZS Pharma (NasdaqGM: ZSPH - news) for $2.7 billion in 2015.

Analysts, reacting to the approval announced late on Friday, said on Monday that the label for Lokelma was modestly better than for Vifor Pharma's rival therapy Veltassa, which also treats excess potassium levels or hyperkalemia.

In particular, AstraZeneca's drug has a faster onset of action, a better drug-drug interaction profile and can be stored indefinitely at room temperature, Deutsche analysts said. However, both drugs are still deemed unsuitable for acute life-threatening hyperkalemia episodes.

"Whilst we must concede the label is not a best-case, we nonetheless see it as an improvement on the only incumbent option, Vifor's Veltassa," Barclays (LSE: BARC.L - news) analysts said in a note. "Our thesis remains that Lokelma will be the dominant player in the eventual $3 billion hyperkalemia market."

AstraZeneca is banking on a range of new drugs to return the company to sales growth in 2018. Last week it reported first-quarter results that showed the impact of generic competition to older medicines, but promising sales of newer ones.

AstraZeneca shares, which fell on Friday's financial results, were up 2 percent on Monday. (Reporting by Ben Hirschler; editing by Jason Neely)