Merck (NYSE:MRK) gained Food and Drug Administration approval for its powerful new cholesterol drug Liptruzet, a combination of two already-approved drugs, Pfizer's (NYSE:PFE) Lipitor and Merck's Zetia.
Merck already sells a combination drug containing Zetia and Zocor called Vytorin. Zocor and Lipitor are in the same class of drugs called statins, but Lipitor is considered more powerful.
In a clinical trial, Liptruzet taken for 12 weeks lowered LDL cholesterol -- that's the bad kind -- by 53% to 61% depending on the dose. Lipitor alone in the same trial reduced cholesterol by 37% to 54% depending on the dose. Zetia by itself reduced LDL cholesterol by just 20%.
Interestingly, despite Lipitor being a better statin than Zocor, the LDL cholesterol data doesn't look that much better than for Vytorin.
In the clinical trial supporting the approval of Vytorin, the combination pill reduced LDL cholesterol by 45% to 60%. It's difficult to compare results between trials since there may be a different makeup of the subjects enrolled in the trials, but there's somewhat of an internal control because both trials tested Zetia alone. In the Vytorin trial, the group that got Zetia by itself had a 19% reduction in LDL cholesterol, similar to the 20% seen in the Liptruzet trial.
One advantage of Liptruzet over Vytorin seems to be at the lowest dose -- 53% vs. 45% -- which could be helpful for patients that can't tolerate high doses of statins due to side effects including muscle aches.
Assuming they're priced the same, Merck doesn't really care whether patients take Liptruzet or Vytorin. The new combination product could help it capture some patients that are currently taking generic Lipitor. It's easier for a doctor to add a second drug than to change from one drug to two different drugs. Patients could have just added Zetia to their Lipitor, but then they'd have to take two separate pills. Liptruzet is more convenient if nothing else.
The biggest loser here could be AstraZeneca's (NASDAQ:AZN) Crestor, the other powerful statin on the market, which is now without a comparable Zetia-containing combination drug. If doctors are going to start a patient on a statin with the expectation that they might want to add Zetia later, it makes sense to start with Lipitor.
Of course, that's just adding insult to injury since Lipitor is also preferred because it's available as cheap generic. In the first quarter, U.S. prescriptions for Crestor were down 7% while total prescriptions for statin products increased by 1%.
All eyes now turn toward the Improve-It trial, which is testing Vytorin against Zocor to see if the combination drug not only lowers cholesterol but also decreases heart-related events: heart attacks, strokes, and the like. If the combination drug really does improve it, we'll likely see an increase in the use of Vytorin and probably Liptruzet as well.