Schering-Plough says that US regulators have accepted an application to review a combination pill containing the firm’s blockbuster allergy drug Claritin with Merck & Co’s asthma treatment Singulair.

The two drug majors have filed a New Drug Application with the US Food and Drug Administration in a bid to get marketing approval of the combination of Claritin (loratadine) and Singulair (montelukast) for the treatment of allergic rhinitis symptoms in patients who want relief from nasal congestion. S-P noted that in clinical trials, side effects were similar to placebo and included headache, fatigue and dry mouth, while the combination product “provided a consistent and clinically relevant effect on congestion that was not demonstrated with the individual components”.

If approved, the hay fever medicine would be sold through the companies’ joint venture. S-P and Merck already market the cholesterol-buster Vytorin - a combination of Zetia (ezetimibe) and Merck's statin Zocor (simvastatin) and are working on a combination of Zetia and Pfizer’s blockbuster Lipitor (atorvastatin).