Merck Sharp & Dohme has won expanded use from the European Commission to market its new diabetes therapy Januvia (sitagliptin). It is the only drug within the DPP-4 class of medicines to have received the thumbs up for once-daily use, and has now also been cleared as an add-on therapy to a sulfonylurea or a sulfonylurea plus metformin.

Januvia was first approved in the European Union in March 2007 for the treatment of type 2 diabetes in combination with either metformin or, in certain patients, with a thiazolidinedione, such as GlaxoSmithKline’s Avandia (rosiglitazone) or Takeda’s Actos (pioglitazone). And the two new indications will be adopted in all 27 countries of the European Union, where it’s estimated that more than 53 million people have diabetes.

DPP-4 inhibitors are a new class of oral agents that target the incretin system and it is thought that they reduce glucose more effectively without producing the side effects of present treatments. Overall, Januvia has been cleared in 60 countries around the world, reeling in $185 million in the third quarter of 2007 alone.

And Merck is looking to benefit further from this initial success, with 49 studies completed or underway and five more studies set to begin this year. Indeed, its leading position in the class is likely to be maintained as Novartis’ one-time contender Galvus (vildagliptin) has been hamstrung by liver safety issues. Although it is now approved in Europe as a lower dose than was originally developed, the Swiss giant now says it may not re-file in the USA after the country’s Food and Drug Administration requested additional data for a second time.

And there is precious little else likely to topple Januvia’s dominant position, the closet being Takeda Pharmaceutical Co, which earlier this month filed its new diabetes treatment alogliptin in the USA in a bid to reduce its reliance on its $2.8 billion a year Actos.

Merck does need Januvia to perform well: this year sees the US loss of its patent covering the blockbuster Fosamax (alendronate), sales of which are expected to tumble from around $3 billion to $1 billion. It is also on track to have trimmed 7,000 from its global workforce by the end of the year as part of a restructuring programme implemented in 2005.