Pfizer halts development on new Fibro drug esreboxetine

Pharmaceutical giant Pfizer Inc announced this week that they are ending development on two drugs that had been in final human testing in order to move staff and funding onto experimental drugs with more potential.

One of the drugs in question was a compound for Fibromyalgia Syndrome (Fibro), known by the chemical name esreboxetine. The other was a drug for generalised anxiety disorder, known only by the designation PD 332,334.

Neither compound had been seen as a likely "blockbuster drug" for Pfizer because other drugs to treat these conditions already are on the market, including Pfizer's own Lyrica, which was the first drug to get US FDA approval as a treatment for Fibro and which is currently going through the process of applying for marketing approval in the EU as well.

Pfizer said it reviewed results from the first late-stage study for PD 332,334 and all the data for esreboxetine, "along with current market dynamics," before making the decision.

Spokeswoman Kristen Neese told The Associated Press:

"They're not products that really meet an unmet medical need...We'd rather devote our resources to other areas."

Pfizer has been going through a restucturing and assessment process for some time now as it seeks to address the issue of its cholesterol treatment Lipitor being expected to lose patent protection in November 2011. Lipitor is the world's top-selling drug with nearly US$13 billion in global annual sales — more than a quarter of Pfizer's total revenues.

By the time a drug reaches the market, pharmaceutical companies have typically spent hundreds of millions of pounds developing the drug. With such heavy costs, a company in Pfizer's position needs to know that the drug will recoup enough money.

It would seem that Pfizer feel that with Lyrica, they have cornered as much of the Fibro market as they will be able to. The fact that two more drugs - Cymbalta and Savella - have already acheived FDA approval as treatments for Fibro, and more drugs are already in the pipeline - will also have had an impact on their decision.