Expert FDA Panel Backs Schizophrenia Drug It Once Rejected
Jul. 19, 2000 (Washington) -- A new antipsychotic drug once denied FDA approval for the treatment of schizophrenia because of a potential risk for heart-related side effects earned a favorable recommendation Wednesday from an FDA expert advisory committee two years after initially being deemed "non-approvable."
Called Zeldox, it belongs to a class of drugs known as "atypical" antipsychotics because of their propensity to cause fewer side effects such as the involuntary muscle spasms historically associated with older antipsychotic medications. While Zeldox may not be the safest atypical antipsychotic alternative, there is a lot of data to suggest that doctors are willing to accept a risk of rare heart-related events for an additional treatment option, committee members almost unanimously concluded.
The FDA initially decided not to approve Zeldox based on its prolonging affect on the QT interval. The QT interval represents the time it takes for the heart to electrically recover after contracting to push the blood out into the body. Although it is not fully known, it is thought that increasing the QT interval leads to abnormal and potentially fatal heartbeats.
Pfizer, the maker of the drug, has since completed a head-to-head safety comparison of Zeldox, at its optimal dose, with several other antipsychotics. The research showed that Zeldox's affect on the QT interval was not much different from the other drugs.
Other factors in favor of Zeldox's approval are the absence of side effects found with other atypicals such as weight gain, says Edmund Harrigan, MD, executive director of CNS Therapeutics, a division of Pfizer Global Research and Development. Considering these mitigating factors and that atypical antipsychotics remain the modern day treatment of choice for schizophrenia despite these side effects, it is safe to assume that doctors would want Zeldox as a treatment option, he said.
Despite agreeing with Pfizer in principle, committee members also expressed some reservations. Those reservations were based in part on the lack of data regarding Zeldox's use in elderly patients, as well as a general lack of data regarding how drug-to-drug interactions might affect Zeldox's levels in the blood.