In the not-too-distant past (ie. August), the US Food and Drug Administration (FDA) was vilified by some and praised by others for the steep increase in the number of new molecular entities (NMEs) it was approving, though that supposed leniency may have begun to shift in just the past week.

FDA's drug review process has long been recognized as the gold standard globally (FDA even mentioned that gold standard moniker in congressional testimony) and as recently as 2008, about half of NMEs that came up for approval were rejected. However, this year (at least through August), FDA shifted to a supposed "golden age of approvals" by approving 88% of all NMEs, while only rejecting three of 28 NMEs.

As Forbes and BioMedTracker noted in a story from August, under the headline "FDA is Basically Approving Everything," FDA's approval rate for NMEs has been topsy-turvy in recent years. In 2008, the agency approved 20 NMEs and rejected 20, while in 2009, the NME approval rate fell to 44%, though that rate then rose to 86% in 2011, fell to 60% in 2013, and last year rose to 88%.

More recently, the agency's decision to approve the twice-rejected female libido drug Addyi had a number of commentators up in arms over the agency's leniency.

FDA Acting Commissioner Stephen Ostroff addressed this supposed leniency at a recent science writers meeting at the agency and told reporters that the high rate was due to a number of factors, including new regulatory review pathways and significantly better applications from industry.

Other industry insiders also note that there's been a shift in industry between 2008 and today, with an increasing number of agency/sponsor meetings earlier in the drug development process, which can result in better submissions. And that rate may increase more with the passage of the 21st Century Cures Act, which is intended to cut red tape and accelerate new approvals even further.

Shift?

But over the past week the agency seems to be taking a stand against this notion that it's become too lenient. Three complete response letters, which are basically FDA rejection letters, have ben issued in the past week, and not just to smaller companies, but to some of the biggest in the industry, including Pfizer, AstraZeneca and Shire. 

But saying that there's been a shift to a more stringent FDA can be tricky because the agency didn't reject each of the applications for the same reasons. For instance, in AstraZeneca's case, FDA asked for more clinical data, while for Shire, FDA requested more product quality information. And projecting the future of new drug application approval rates based on past experience is nearly impossible as every application is different.

However, with four more approval decisions due by the end of this week, industry may have a firmer grip on just how lenient the agency has become, particularly as it transitions between commissioners.