Crestor也许是Baycol撤消的“唯一变故”

LONDON (Reuters Health) - AstraZeneca's cholesterol lowering drug Crestor could be the "only real casualty" following this week's withdrawal of Bayer's Baycol, according to analysts at Prudential Financial.

In a note dated August 9, they said scientific opinion suggested that Baycol 's side effect problems would not affect other marketed statins or Crestor, which is due out next year.

"Based on the conversations we've had, the literature we've analysed, and the fact that the FDA appears to recommend all of the remaining statins as replacements for Baycol, we think that Baycol's problems might be unique unto itself."

However they warned that although Crestor might have nothing to worry about from a scientific point of view, as the new entrant on the block it could suffer from a marketing standpoint.

"The only real casualty here could be Crestor from the standpoint that competitors might put the fear into physicians that Crestor, without a wealth of experience on the market, might be another Baycol in disguise," the analysts said.

Baycol was withdrawn after being linked to 31 deaths in the United States from rhabdomyolysis, which results in muscle cell breakdown and release of potentially toxic cell components into the blood stream.

"Its withdrawal could free up $1 billion in worldwide revenues that becomes a jump-ball for the other statins, and this marketshare will probably be divided up quickly--within a quarter or two," Prudential Financial said.

The Datamonitor consultancy also predicted that Crestor might be affected by Baycol.

"Although Baycol's withdrawal should be good news for AstraZeneca as its new superstatin, Crestor, is not only more potent than other statins, but (unlike Baycol) appears to have no effect on the cytochrome CPY 3A4 system, it is possible that approval could be delayed as the FDA more rigorously reviews side-effect data, in the light of the concerns surrounding Baycol."

Datamonitor said sales figures showed that the statins were the highest selling class of drugs globally in 2000, valued at $16.7 billion, led by Merck's Zocor at $5.3 billion and Pfizer's Lipitor at $5 billion.

Although Baycol's $586 million sales accounted for a quarter of Bayer's revenues, they represented only 3.5% of the statin market. "Therefore while Baycol is a major product for Bayer, its withdrawal is expected to have little impact on the overall market for statins, with leading brands picking up new prescriptions."

Datamonitor said Baycol was "markedly different" from other statins in that it was potent at very low doses. "Available strengths range from 0.2 to 0.8 mg compared with 5mg to 80mg for Lipitor and Zocor. Given that even the highest dose does not offer efficacy levels on a par with Lipitor, it is clear that higher dosage levels of Baycol were related to increasing side effects."

The note says that in general statins have a low side effect profile. "However with the exception of pravastatin (Pravachol/Bristol-Myers Squibb), most of the leading statins are metabolised to a greater or lesser extent by the cytochrome p-450 system in the liver, which is associated with a large number of drug-drug interactions. Therefore, Lipitor and Zocor are theoretically likely to promote rhabdomyolysis, but the small number of case reports has revealed Baycol to have greater toxicity."

The consultancy adds that the FDA advice that patients coming off Baycol should be switched to one of five other statins would reassure physicians that the drugs were generally safe. "Nonetheless, the withdrawal has generated media coverage which is expected to cause concern among physicians and patients worried about a class effect. For this reason, manufacturers of other statin brands are likely to respond to the Baycol news with a strong defence of their product safety records."