High Hopes for Merck, Schering-Plough

Vytorin also is part of a bigger drama in a cholesterol market filled with many unanswered questions. For example, how will it fare when a new pill from Pfizer(PFE Quote) is expected to reach the market in a few years? The pill combines Lipitor with an experimental drug.

What happens when a flood of generic copies of Zocor and Bristol-Myers Squibb's (BMY Quote) Pravachol are marketed?

Will managed care companies steer patients to cheaper generics, raising copayments or restricting choices of Vytorin and brand-name drugs?

And what happens to Crestor, which has been attacked repeatedly by critics but which recently received a favorable opinion from the Food and Drug Administration? Although AstraZeneca agreed to strengthen some label warnings, the FDA said Crestor's side effects are similar to those of other cholesterol drugs.

Crestor has had disappointing U.S. sales. The near-term trend doesn't appear favorable, although it's hard to tell how much the latest FDA pronouncements will help Crestor in terms of removing the clouds of criticism.

Research by Morgan Stanley and IMS Health show that new prescriptions of Crestor accounted for 6.7% of the U.S. cholesterol market during the fourth quarter of 2004. At the current prescription-writing rate, Crestor will have a 5.6% market share during the first quarter of 2005.

Vytorin's market share is expected to climb to 4.9% from 3.5%. Zetia's new prescription market share is expected to move to 7.6% from 7.5%. Zocor's market share should slip to 17.5% from 17.8%, Morgan Stanley says.

New prescriptions are a better indicator than total prescriptions, when comparing new drugs against each other or comparing new drugs vs. older drugs such as Lipitor, the market leader. It had 47.3% of new prescriptions in the fourth quarter and is projected to have 47.2% during the first quarter, says Morgan Stanley. In second place was Zocor with a 17.8% market share for 2004's fourth quarter and a projected 17.5% for the first quarter of 2005.

Making a Name in a Crowded Field New Prescription Market Share of Cholesterol Drugs
Drug	4th Quarter 2004	1st Quarter 2005 (projected)
Lipitor	47.3%	47.2%
Zocor	17.8	17.5
Pravachol	8.3	7.8
Zetia	7.5	7.6
Crestor	6.7	5.6
Vytorin	3.5	4.9
Sources: IMS Health, Morgan Stanley