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 Impax Laboratories (NASDAQ:IPXL) traded nearly 12% higher on Thursday -- reaching a new all-time high -- following news that the FDA has approved the company's Parkinson's disease treatment, Rytary.

So what: The FDA had rejected Rytary, a long-acting oral capsule form of carbidopa-levodopa, two years ago over concerns regarding Impax's drug manufacturing plant in Hayward, Calif., and these concerns followed Impax to its new site in Taiwan. However, Impax has evidently overcome these quality-control issues and expects to begin distributing Rytary by February. Rytary could benefit approximately 1 million Americans living with Parkinson's, and it represents an improvement over existing levodopa treatments, which are only effective for roughly four hours at a time when taken orally.

Now what: Impax had formerly partnered with GlaxoSmithKline to market Rytary outside the United States, but that deal died following the FDA rejection two years ago. Since then, other companies have developed competing Parkinson's treatments, including AbbVie's Duodopa, which is already available by prescription in Canada.

Cowen analyst Ken Cacciatore projected potential annual sales of $300 million for Rytary, which would boost Impax's top line by approximately 60% over 2013's full-year sales. It would also drop the company's price-to-sales ratio to roughly 2.9, which is close to Glaxo's and well below AbbVie's current P/S ratio of 5.4. That makes Impax worth watching, and the company might even be worth buying if it can show progress in bringing some of its other development-stage drugs to market.