Researchers say trials of Pfizer Inc.'s Neurontin epilepsy treatment for uses that were not yet approved may have been skewed to emphasize favorable results.
Meg Tirrell, Bloomberg, Nov 11, 2009
Nov. 11 (Bloomberg) -- Researchers say trials of Pfizer Inc.'s Neurontin epilepsy treatment for uses that were not yet approved may have been skewed to emphasize favorable results.
Comparisons of internal company documents with published data from 12 clinical trials found inconsistencies between data that made it into the medical journals and findings from the original trials, according to a report in tomorrow's New England Journal of Medicine. Discrepancies included reports of positive results from trials that were initially found to be negative, and primary study goals reported as secondary study goals.
Pfizer paid $430 million in criminal fines and civil penalties in 2004 for urging doctors to prescribe Neurontin for off-label uses. The drugmaker said the new review isn't credible and the company didn't attempt to mislead the medical community.
"The trouble is, as a scientist, the publication has always been held up to me as the truth," said Kay Dickersin, a professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health and an author of the study. "It's the scientific record. What this study indicated is we can't believe that record."
The company documents were obtained as a result of litigation against Pfizer and a subsidiary for promoting Neurontin, or gabapentin, for so-called off-label uses, or those not approved by the U.S. Food & Drug Administration, according to the journal report.
Dickersin said she was an expert witness for the prosecution in litigation against Pfizer. She agreed to participate on the condition that she be allowed to publish information from unsealed documents, and she diverted her earnings to related Johns Hopkins research, she said.
Of 21 primary study objectives of off-label uses of Neurontin described in original documents, six weren't included in published reports and four were reported as secondary goals, according to tomorrow's study in the journal. For eight of the 12 published trials, the definition of the primary study goal differed between the original and published documents.
Seven of the nine trials published as full-length research articles reported statistically significant results for the study's main goal, and in more than half of those, the outcome differed between the published account and the original documents, the study showed.
"The suggestion that Pfizer attempted to mislead the medical community about the effectiveness of gabapentin for certain off-label conditions is untrue," Pfizer said in an e- mailed statement. "We believe the review suffers from significant bias, insufficient data, poor methodology, and cannot pass the threshold of credible scientific research."
Physicians are allowed to prescribe drugs for uses not approved by the FDA, and drugmakers are allowed to provide publications about off-label uses, Dickersin said.
More disclosure is needed to ensure the validity of studies on off-label uses funded by industry, Dickersin said.
Doctors "have nothing but the published literature" when deciding how to use drugs for unapproved uses, she said.
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