UPDATE 1-EU regulator to review anti-obesity medicines

* To examine possible link with rare cases of severe liver injury

* Drugs contain orlistat, including Roche's Xenical and GSK's Alli (adds details)

LONDON, Sept 22 (London) - The European Medicines Agency said it would look into anti-obesity medicines that contain orlistat, including Roche's Xenical and GlaxoSmithKline's Alli.

Its move follows some rare cases of severe liver injury that could affect the drugs' benefit-risk profile.

The EMA, the European Union's drugs regulator, said the review would include the prescription-only medicine Xenical (orlistat 120 mg), and the lower dose over-the-counter-medicine Alli, as well as other medicines containing orlistat.

The risk of liver reactions was well known, the agency said in a statement on Thursday, and had been kept under close review. Its new probe focused on the strength of evidence relating to severe liver injury.

It said there were 21 suspected cases of liver injury, of which four were severe, reported among patients taking orlistat 120 mg between August 2008 and January 2011.

However, it said of the 21 cases of severe liver toxicity between 1997 and January 2011 for which a causal link to orlistat could not be excluded, alternative explanations for the injury were present in many.

The EMA said the cases should be considered in the context of the cumulative use of the medicines by 38 million patients.

GlaxoSmithKline is in the process of selling Alli, sales of which have fallen since a strong start in 2007 due to concerns about liver injury, as part of an overhaul of its non-prescription medicine business. (Reporting by Paul Sandle; Editing by David Hulmes)