I think this is an example of the aggressive style Pfizer uses to get what they want. Pfizer runs studies to show its statin is better than everything else.

They then lower they price a bit to encourage insurances to pay for brand name Lipitor instead of the generics. What you, Bob, don't know is that when drugs go generic (like Zocor, Pravachol, Mevacor now), the other drugs in that family, that are STILL brand like Lipitor, are bumped up to the next tier (like your Zetia). However, Lipitor used aggressive marketing tricks to keep it on tier one. Insurance companies want to pay as little as possible and so Pfizer knows how to sway them. It goes like this: "We lowered our price a bit, and show studies that reveal that your patients suffer less likely use of hospital and other medications, so using Lipitor tier one, is a cost saver". The study they are most likey using is the head to head, with Zocor..which was published just over a year ago.

Zetia is most likely up there in tier two, just because it is a "brand name".
Vytorin would be up there too.

Here is a bit of history for an example. Biaxin came out first (Abbott).this is a new form of erythromycin, improved to avoid severe GI upsets and improve bacterial killing effectiveness. Zithromax came out a little more than a year later (in the same family), and did not do well, since Biaxin was well accepted by doctors. So what happened? Pfizer reformulates the Zithromax into a "pak" so patients punch them out of a card. (once a day use was new in macrolide dosing as well).
Then they LOWERED the wholesale price of Zithromax to about 75% of what Biaxin cost. And bingo..Zithromax took over the whole market share, in no time! Pfizer knows how to get things done!

Putting Zetia in tier two, is not a denial of coverage. In a denial, you can
get prior authorization, to cover a noncovered item. It is slightly possible you could get prior auth for changing tiers, but I have only seen this a few times with antibiotics, and once with a blood pressure pill. (both were thru HMO's).
Since Zetia is still covered, you would have to check with your insurance company to see if any recourse in price is available to you.

It is a bummer, I know. Insurance companies are very powerful these days!