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* Advair restored to Express Scripts 2015 formulary list
* Move may boost use but prices still seen under pressure
* GSK diabetes drug Tanzeum not included in Express list
* GSK shares up 1.3 percent
By Ben Hirschler
LONDON, Aug 4 (Reuters) - GlaxoSmithKline (GSK) received a boost on Monday from a decision by Express Scripts, the largest U.S. pharmacy benefit manager, toreinstate its top-selling lung drug Advair as an approved drugin 2015.
The British drugmaker's business has suffered since Januaryafter Advair was dropped from various formulary lists, includingthat of Express Scripts, adding to pressure on an inhaledmedicine that is also facing growing price competition fromrival products.
Drugs excluded from such lists have to be paid for out of patients' pockets, hitting their use. Pharmacy benefit managersadminister prescription drug benefits for employers and healthplans.
Disappointing U.S. sales of GSK's 15-year-old respiratorydrug were largely to blame for the company's worse-than-expectedsecond-quarter results, which prompted the company to cut its2014 earnings outlook last month.
Advair makes up nearly a fifth of GSK's sales but demand iseroding both in Europe, where it faces competition from copycatversions, and in the United States, due to lack of formularycover and keen competition from AstraZeneca's Symbicort.
U.S. sales of Advair, which is used to treat asthma andchronic lung disease, tumbled 19 percent in the second quarterin constant currency terms.
Even after the Express Scripts change, however, Advair willstill be at a disadvantage, according to Credit Suisse analysts,since it is not listed as a preferred treatment, unlikeSymbicort and Merck & Co's Dulera.
The analysts also believe Advair prices are likely to remainunder heavy pressure as GSK strives to secure market share.
Furthermore, GSK's new lung drug Breo remains excluded fromthe Express Scripts formulary, along with its new injectablediabetes drug Tanzeum, which belongs to the same so-called GLP-1class as Novo Nordisk's Victoza.
Victoza was already excluded from the list but GSK has beenhoping to win business for its rival medicine by pricing Tanzeumat a discount to Victoza.
GSK shares were 1.3 percent higher by 1400 GMT.
Express Scripts also said late on Friday it would drop twokey anaemia drugs, Epogen and Aranesp, sold by Amgen.
(Editing by David Holmes)
