Merck's Singulair sales free-fall 90% in 4 weeks

With all of the pressures in place to promote generics of popular branded drugs, the time it takes to go from blockbuster to just buster has become remarkably short. New data shows that sales of Merck's ($MRK) asthma and allergy drug Singulair fell nearly 90% in just the four weeks since the generics were approved.

"There's been a rapid decline and loss of sales," MarketWatch quotes Adam Schechter, president of Merck's global human-health unit, telling investors in New York. 

No kidding.

Schechter told analysts in July that history indicated it would take two months to lose 90% of market share. Well, history indicated otherwise, since sales fell 87% in a month.

Singulair has been the company's biggest seller and accounted for $3.3 billion of Merck's ($MRK) sales last year. For the most recent full quarter, Singulair brought in $1.43 billion. But with 10 generics lined up against it, a crash was inevitable.

History has not been kind to any of the recent blockbusters that have lost patent protection. Plavix, the top-selling drug in the world, fell off patent in May, and Bristol-Myers ($BMY) reported a 60% year-over-year sales drop for the second quarter, to $701 million. That was for only one month of the quarter.

Other recent generics launches grabbed 90%-plus market share as multiple versions hit the market. Eisai's Aricept saw its share nosedive immediately. Within a couple of weeks, with just a couple of rivals on the market, the brand had only 27% of the market. Soon after the 6-month mark, when a half-dozen or so new copies hit, shares fell below 10%.

- here's the MarketWatch story 

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