Whitehouse Station, NJ - Merck's blockbuster cholesterol-lowering agent, Zocor (simvastatin), loses its US patent protection tomorrow, when the first generic competitors will appear. This move is expected to have a big impact on the statin market, affecting sales of not just Zocor but also the other major branded statins, Lipitor (atorvastatin, Pfizer) and Crestor (rosuvastatin, AstraZeneca).

The US statin market is estimated to be worth a massive $16 billion each year at present, but this figure is now expected to be cut dramatically as health insurance companies and pharmacy benefit managers switch many patients to generic simvastatin.

The statin market is currently dominated by Lipitor, with Zocor in second place. Although sales of Zocor will undoubtedly be slashed by generic competition, Lipitor is also likely to suffer. While the highest dose of atorvastatin is more potent than simvastatin, it has been estimated that most patients can reach target LDL-cholesterol goals with simvastatin, and this is bound to encourage insurers to insist patients switch to this cheaper alternative.

The Wall Street Journal recently reported that a survey of 140 doctors showed that half of them said they would shift away from prescribing Lipitor, especially in lower-risk patients, when generic simvastatin became available [1].

But Merck is understood to be fighting the generic competition by arranging deals with health insurance companies so that Zocor has lower patient copayments than the first generic versions of simvastatin.

United Health Group, a large US health insurance group, said it had negotiated reduced prices for Zocor with Merck. The insurance company will move Zocor into the cheapest band of its formulary, reducing the patient copayment from $25 to $10, while the new generic version of the drug, made by Teva Pharmaceuticals, will be in the most-expensive copayment group, according to a report in the Wall Street Journal [2]. When the patent protection expires on a drug, the first company to file for a generic usually gets six months of market exclusivity, so generic competition is limited to start with. In this case, Merck has also signed a deal with another generics manufacturer to sell its own generic version of simvastatin.

Another insurance company, WellPoint, is said to have entered into an agreement with Merck to sell brand-name Zocor through its mail-service facility at a significantly lower price than the generic price and take a generic copay.

Merck reported worldwide sales of Zocor of $1.06 billion in the first quarter of this year, down slightly from last year because of patent expiries in other markets. US sales were up 13%. The company is forecasting full-year 2006 Zocor worldwide sales of $2.3 billion to $2.6 billion.