Merck’s new first-in-class diabetes drug Januvia is off to a strong start, according to data from ImpactRx, a market research firm which tracks both new prescriptions and free samples.“In situations where physicians are making a brand choice, it’s clear that Januvia is off to a strong start and Merck looks to be putting the promotional muscle behind it to make that happen,” ImpactRx SVP of strategic development Patrick Angelastro told Reuters.For the week ending Nov. 17, Januvia accounted for 14% of new prescriptions written plus new samples dispensed in the Type 2 diabetes market, according to ImpactRx data.During the same week, Lilly and Takeda’s Actos accounted for 23% of new prescriptions plus samples. Metformin, a generic drug, accounted for 26%.Januvia was running neck and neck with GlaxoSmithKline’s Avandia and Amylin and Lilly’s Byetta among endocrinologists tracked over two weeks ending Nov. 17. Januvia accounted for 20% of new prescriptions plus new samples, compared with 22% for Byetta and 19% for Avandia. Actos lagged behind at 10%, with metformin at 16% among endocrinologists.Januvia won US approval in mid-October to treat adults with Type 2 diabetes and is part of the emerging drug class of DPP-4 inhibitors, which enhance the body’s ability to lower elevated blood sugar. Novartis filed for FDA approval of its DPP-4 inhibitor Galvus in March. Earlier this month, the FDA extended its review of Galvus by three months. Analysts say the two drugs have the potential to bring in combined sales of $5 billion by 2010, if no major safety issues emerge.