Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of biotech company Raptor Pharmaceuticals (NASDAQ:RPTP) spiked as much as 17% after the Food and Drug Administration approved its nephropathic cystinosis drug, Procysbi. Shares ended the day up 5.3%.

So what: Procysbi is a twice-daily oral medication that, from an ease-of-use standpoint, easily trumped Mylan's (NASDAQ:MYL) Cystagon, which has to be taken four times daily and can interrupt sleep patterns. Having proved non-inferior to Cystagon, barring concerns over Procysbi's safety, there didn't seem to be much that was going to prevent an FDA approval. According to JMP Securities, the drug has peak sales potential of $60 million in the United States.

Now what: Congratulations to Raptor and shareholders for its first drug approval. However, $60 million isn't going to make much of a dent unless it gets Procysbi approved overseas as well. In addition, Raptor had already had a huge run-up into today's PDUFA decision, so taking some profits off the table here may not be such a bad idea.

Craving more input? Start by adding Raptor Pharmaceuticals to your free and personalized Watchlist so you can keep up on the latest news with the company.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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