Could it be? Are they getting a divorce over Vytorin? No, sorry to excite you. But the drugmakers are ending their respiratory joint venture and their eight-year effort to market a combination of their Claritin and Singulair medications, which are used to treat allergic rhinitis. Here is the statement.

You may recall that the FDA issued a non-approvable letter two months ago. At the time, the drugmakers said they were evaluating the FDA response, but provided no additional information, which is another way of saying they were also evaluating their options.

Which party pulled the plug? They don’t say, of course. But relations between the two drugmakers has not been particularly warm and fuzzy these past few months, ever since controversy erupted over the handling of the Enhance trial that was designed to boost sales of Vytorin, the cholesterol pill they market jointly.

Nonethless, the drugmakers were quick to note that the latest move “has no impact on the business of the Merck/Schering-Plough cholesterol joint venture,” which also markets Zetia, one of two components in Vytorin. The other is Zocor. Meanwhile, Schering-Plough expects to receive payments totaling $105 million from Merck now that the respiratory deal has run out of breath.