We now have five full months (getting close to a half-year’s-trend-line) of Vytorin/Zetia IMS sales data to inform — and sharpen — our views on 2008, as of last night, so I’ll offer the below, as additional food for thought. [I'd genuinely appreciate anyone's differing views on these topics, for it could be that I have missed something fundamental here -- if so, feel free to leave a comment in the comment box. . .]

Recall that back on April 21, 2008, Merck projected that it would see a fall-off of about $700 million in its 2008 Equity Income line, “solely attributable” to the ENHANCE study fall-out, compared to 2007 Equity Income levels.

By the way, I did my own math, to create the graphic at right, back then — and it looks to be even more accurate now, than it did, then. How so?

Well, for all of 2007, Schering SEC-reported Equity Income from Operations of $3.663 billion from its share of the Cholesterol Joint Venture (see page 124 of the linked 2007 Form 10-K, bottom row, left column). If we were to assume that the 23 percent downturn in scrips will persist (but grow no worse) for the balance of 2008, we would expect that the actual fall-off would be closer to $850 million for 2008:

Viz — 23 percent of $3.663 billion is — yep — $843 million.

That decline is actually closer to the higher-end of my $700 to $900 million prediction early in the morning of April 21, 2008.

Cool.