Eli Lilly and Co. announced that it developed a new schizophrenia drug which doesn't have the unpleasant side effects of its current top-selling drug, Zyprexa (substance: olanzapine). Lilly sells billions worth of Zyprexa each year, but there are serious health concerns regarding it, some of which have been systematically played down by the company, according to internal documents leaked to the internet late in 2006.

Among other health hazards, Zyprexa causes more or less weight loss in around 90% of its subjects and may cause diabetes and all the collateral problems associeted with the disease. Overall, Lilly has agreed to pay at least $1.2 billion to almost 30,000 people who claim they were injured by the drug, with some lawsuits still pending.

Unlike Zyprexa, which acted on dopamine and serotonin receptors, the new drug acts on certain proteins in the brain called mGlu2/3. A phase II study published in the scientific journal Nature Medicine has shown similar antipsychotic activity as Zyprexa but did not have its most common adverse effects such as increased prolactin elevations, extrapyramidal symptoms (involuntary movements or muscle stiffness), or weight gain.

"These data provide compelling new evidence that mGlu2/3 receptor agonists have antipsychotic properties and may provide a completely new therapeutic approach for treating schizophrenia and, perhaps, other neuropsychiatric disorders," Lilly's executive vice president of science and technology, Steven Paul, M.D.

The phase II trial involved 196 patients with schizophrenia, of which 118 patients completed the four weeks of planned study treatment with the new drug, codenamed LY2140023. Schizophrenia affects at least 1% of the population.

"We want to see much higher levels of investment from the pharmaceutical industry in research in drug treatments for schizophrenia that reduce side effects whilst still being effective at combating the symptoms," said Paul Corry of the mental health charity Rethink to BBC News.