UPDATE 2-Solvay challenged in U.S. on male hormone therapy

* Rival firm challenges Solvay’s U.S. patent on Androgel

* Solvay says committed to treatment, evaluating options

(Adds details on Androgel)

AMSTERDAM, June 10 (Reuters) - Belgium's Solvay SOLB.BR said on Wednesday rival firm Perrigo Israel Pharmaceuticals had applied for approval from U.S. authorities to sell a generic version of Solvay's treatment for testosterone deficiency.

Solvay said Perrigo Israel's PRGO.OPRGO.TA application with the U.S. Food and Drug Administration challenged a United States patent relating to its treatment Androgel, which runs through the next decade.

“Such procedures are not unusual for branded products in the United States,” Solvay said in a statement.

Worldwide sales of Androgel rose by 9 percent to 337 million euros ($475.5 million) last year. Solvay’s total pharmaceutical sales were 2.7 billion euros.

Solvay, one of very few drug-chemicals hybrids left, has been confronted with several legal challenges over Androgel, which is used to treat men with low testosterone levels.

At the start of this year, the Federal Trade Commission filed a complaint challenging agreements in which Solvay allegedly paid generic drug makers Watson Pharmaceuticals and Par Pharmaceutical Companies to delay generic competition.

In response to the FDA filing, Solvay said on Wednesday it remained fully committed to Androgel and to protecting its intellectual property. The company was now evaluating its options.

The original drug manufacturer can sue in a U.S. court if it disagrees with the generic producer’s claims of invalidity or non-infringement. (Reporting by Aaron Gray-Block and Philip Blenkinsop; Editing by Hans Peters)