Regeneron (NASDAQ:REGN) is today's big loser in the biotech space because of a new set of FDA concerns over its PCSK9 drug. The FDA is now concerned that this class of drugs, aimed at lowering "bad" cholesterol in the bloodstream, could have a number of neurocognitive adverse effects in patients. Amgen (NASDAQ:AMGN) has a drug in this class, as well, that is considered a critical product for the company; it also saw shares fall today.

In this video from Friday's Market Checkup, Motley Fool health-care analyst David Williamson discusses this potentially multi-billion dollar blockbuster drug class, and how likely these FDA concerns are to derail these drugs.

David Williamson has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.