UPDATE 2-FDA delays Endo's testosterone gel approval

* Endo gets complete response letter from FDA

* Says to file a complete response by mid-2010 (Adds analyst comment)

Oct 19 (Reuters) - U.S. health regulators delayed approval for Endo Pharmaceuticals Holdings Inc's (ENDP.O) Fortesta, a gel used to treat testosterone deficiency.

The company said it received a complete response letter from the U.S. Food and Drug Administration and will address their questions. It expects to file a complete response by mid-2010.

Endo did not reveal details of the FDA letter.

S&P Equity Research analyst Steven Silver viewed the regulatory setback as modest, given Endo's minimal $10 million upfront payment to license drug's U.S. rights. Silver reiterated his "hold" rating and $25 price target on the company's stock.

In August, Endo had bought the U.S. licensing and distribution rights for the product from British speciality pharmaceutical company ProStrakan PSK.L for up to $50 million. [ID:nLQ200445]

In a research note, Thomas Weisel Partners analyst Annabel Samimy viewed the FDA requests as relatively manageable.

Samimy said the factor that is pushing the response to mid-2010 is FDA's request for a washing study, where patients must wash their hands after application to analyze the risk of transference.

The FDA requests do not raise a question of approvability, Samimy, who kept the "overweight" rating and $25 price target on the stock unchanged, said in a note to clients.

Shares of Endo were trading flat at $23.64 in late morning trade on the Nasdaq. (Reporting by Shailesh Kuber in Bangalore; Editing by Pradeep Kurup)