Merck & Co said yesterday the US Food and Drug Administration had accepted the filing for its investigational oral type 2 diabetes treatment MK-0431A, with a verdict on the dossier expected next March.

MK-0341A is a combination product that combines Merck’s already-filed oral dipeptidyl peptidase-4 inhibitor Januvia (sitagliptin) with metformin - a widely prescribed medication for type 2 diabetes - in a single tablet.

The company is hoping for FDA approval of Januvia later this year, and it is in a head-to-head race with Novartis to bring the first DPP 4 inhibitor to market. Novartis’ candidate, Galvus (vildagliptin), which was filed in the USA in March, around six months after Januvia. The filing of a combination product gives Merck a further lead over Novartis in building its DPP-4 inhibitor franchise.

Merck said it is also pushing ahead with regulatory filings for the treatment in countries outside the USA.

DPP-4 inhibitors are designed to provide treatment for type 2 diabetes by enhancing the function of the incretin system, thereby lowering blood sugar levels. This is a different mechanism of action to currently available oral antidiabetic agents, including metformin,

The market for these drugs could be in the region of $3 billion in the USA alone, according to Morgan Stanley, assuming they win a half share of the market for sulfonylureas.