US FDA staff question female sex-drive pill data

US drug reviewers questioned the safety and effectiveness of an experimental pill for treating women with low sex drive, according to documents released on Wednesday.

Boehringer Ingelheim's flibanserin failed to meet the agreed-upon criteria for showing effectiveness in two company studies, Food and Drug Administration (FDA) reviewers said in a preliminary analysis.

Tolerability of the drug was "moderate," the FDA staff also said. Fatigue, drowsiness and sedation were "commonly reported" and "it is not clear if labeling alone will be sufficient to alert women to the numerous drug interactions that exist with flibanserin," they said.

An FDA advisory committee of outside experts meets Friday to consider whether to recommend approval for flibanserin.

The once-a-day pill, nicknamed the "pink Viagra," is the latest attempt to find a female counterpart to Pfizer Inc's successful blue pill for men.

A spokesperson for Boehringer, a privately held German drugmaker, could not immediately be reached for a comment.