Studies drug companies fund after medicines go on sale may be too small to detect rare side effects, a recent German study suggests.
Even if these so-called post-marketing studies do uncover previously undetected adverse events, physicians conducting the trials are often required to keep results confidential, limiting the potential for regulators or patients to learn about safety issues, according to the study in The BMJ.
When drugs are approved based on tests in only a few thousand patients, very little is known about long-term safety or the potential for rare side effects to occur when tens of thousands of people take the medicines, said lead study author Dr. Angela Spelsberg, medical director of the Comprehensive Cancer Center in Aachen, Germany.
