Approval of Leqembi comes after controversial approval in 2021 of Aduhelm, which met with criticism over concerns about that drug's effectiveness, safety, pricing

Extrapolation of the findings from pivotal clinical trials to the approved indication most common for disease severity

Request follows reports that Biogen and the FDA held off-the-books meetings before the drug's approval that may have violated FDA protocol

FDA approved Aduhelm earlier this month, despite advisory committee's conclusion that there was not enough evidence to support its effectiveness

Several experts have said the available evidence about Aduhelm raises significant doubts about its effectiveness

Agency says it has granted approval on the condition that drug maker Biogen conduct a new clinical trial

8-mg dose of naloxone hydrochloride nasal spray now approved with 2-mg and 4-mg doses