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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 1.2 percent (Adds further comment from Express Scripts on Advair move)
By Ben Hirschler
LONDON, Aug 4 (Reuters) - GlaxoSmithKline received aboost on Monday from a decision by Express Scripts, thelargest U.S. pharmacy benefit manager, to reinstate itstop-selling lung drug Advair as an approved drug in 2015.
The British company's business has suffered since Januaryafter the inhaled medicine Advair was dropped from variousformulary lists - including that of Express Scripts - while itfights growing price competition from rival 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.
Express Scripts said the decision followed GlaxoSmithKline's(GSK) willingness to offer the 15-year-old respiratory drug at ahighly competitive price.
"We have changed the formulary status of Advair in 2015 dueto the improved pricing we were able to negotiate for ourclients," said spokesman David Whitrap.
Disappointing U.S. sales of Advair were largely to blame forGSK's worse-than-expected second-quarter results, which promptedthe company to cut its 2014 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 believe Advair prices are likely to remainunder heavy pressure as GSK strives to secure market share.
The decision to move Advair from "excluded" to"non-preferred" means that while GSK's drug will be covered,patients will face a higher co-payment when filling Advairprescriptions than for preferred brands in the same therapyclass.
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 1.2 percent higher by 1445 GMT.
Express Scripts also said late on Friday it would drop twokey anaemia drugs, Epogen and Aranesp, sold by Amgen.
(Editing by David Holmes and Sophie Walker)
