« September 2006

Viagra's Enzyme Action May Give Pfizer Schizophrenia Advance
September 21, 2006

Viagra has improved sex for millions of men and has generated $12 billion in sales for Pfizer Inc. Now the erection pill is providing the world's biggest drugmaker clues to a new way to fight schizophrenia.

Researchers at Pfizer are using insights into Viagra to design experimental drugs that may improve on Zyprexa, the best- selling schizophrenia remedy from Eli Lilly & Co., with $4.2 billion in sales last year. Viagra causes an erection by turning off an enzyme in the body. Blocking similar chemicals in the brain may silence the hallucinations typical of schizophrenia, the researchers say.

A better schizophrenia drug would be a boon for New York- based Pfizer and the 2.5 million Americans who suffer the debilitating mental disorder. Pfizer's current schizophrenia medicine, Geodon, had only 4 percent of the $15 billion spent worldwide in 2005 for anti-psychotic drugs. Researchers say the new Viagra-like compounds will be developed only if shown in human tests to be safer and more effective than existing drugs.

"We believe this drug is going to be different,'' says Frank Menniti, a scientist at Pfizer's Groton, Connecticut, labs. "Our job isn't just to make another anti-psychotic. We need to make a better anti-psychotic than what is out there.''

Starting in 1998, company researchers began probing the role that a family of enzymes called phosphodiesterases play in the human body, says Martin Jefson, a Pfizer scientist. Viagra works by inhibiting one of the enzymes in the group. The scientists figured drugs similar to Viagra that block other forms of the enzyme might be useful in other diseases, according to Jefson.

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