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.

Good morning, fellow Foolish investors! Let's check in on four stocks that could make headlines this morning -- GW Pharmaceuticals (GWPH), Johnson & Johnson (JNJ -0.69%), Durata Therapeutics (NASDAQ: DRTX), and Merck (MRK 0.10%).

GW Pharmaceuticals' Savitex is approved in Switzerland
GW Pharmaceuticals looks poised to move higher this morning after the company announced the approval of Savitex in Switzerland. Including Switzerland, Savitex is now approved in 23 countries for the treatment for moderate to severe spasticity in multiple sclerosis patients.

Savitex is a controversial medication, since it is a cannabis-based mouth spray. Many MS patients have campaigned for the approval of the use of medical marijuana to alleviate MS-related muscle pain -- and it is becoming more widely accepted across Europe, where it is now approved in 17 countries.

The streak of approvals bodes well for GW, which hopes that Savitex will eventually be approved in the U.S. by the Food and Drug Administration as a treatment for both MS spasticity and cancer-related pain. GW is partnered with Otsuka Pharmaceuticals in the U.S., where the companies are conducting phase 3 trials on Savitex.

Savitex is GW's only marketed product, and sales have been fairly unimpressive. Sales of Savitex fell 14% year-over-year to 2.2 million pounds ($3.6 million) in fiscal 2013. However, hopes are still high for GW, which has rallied nearly 300% over the past six months on positive buzz regarding the growth potential of cannabis-based treatments. GW is also working on several other cannabis-based drugs for type 2 diabetes, schizophrenia, epilepsy, cancer, and gastrointestinal inflammation.

Johnson & Johnson's hepatitis C drug portfolio gets bigger
Johnson & Johnson's hepatitis C drug portfolio got a big stronger yesterday, after the FDA approved its NS3/4A protease inhibitor Olysio. Olysio isn't intended to be taken by itself -- it is approved as part of an antiviral regimen which also includes pegylated interferon (such as Merck's Pegintron or Roche's Pegasys), along with ribavirin, an older hepatitis C drug.

The approval shouldn't come as much of a surprise to J&J investors, since an FDA advisory panel had already unanimously recommended the approval of the drug last month. Olysio is only approved for the treatment of genotype 1 of hepatitis C -- the most common type of the virus -- and shouldn't be considered a competitor to Gilead Sciences' (GILD 0.07%) sofosbuvir, which is targeting an approval for the treatment of genotypes 1 through 6.

Therefore, peak sales estimates of Olysio and sofosbuvir vary greatly -- analysts believe that the former will only generate up to $400 million in annual sales for J&J, while the latter could generate up to $6 billion in annual sales for Gilead.

Olysio is J&J's second hepatitis C drug after Incivo, which generated $76 million in sales last quarter. The company also recently acquired GlaxoSmithKline's experimental hepatitis C treatment, GSK2336805, which J&J plans to move into phase 2 studies as a combination treatment with Olysio and another experimental drug, TMC647055.

Durata's Dalvance inches closer to market approval
Durata Therapeutics could also climb higher today, after its new drug application for Dalvance, an injected treatment for skin infections caused by Gram-positive bacteria, was accepted for a priority review by the FDA.

The NDA was originally submitted on Sept. 26, based on two phase 3 trials and an earlier phase 3 study. Dalvance is Durata's only product, but investors have been fairly optimistic about its prospects, and the stock has climbed more than 50% over the past six months.

If approved, Dalvance will likely be compared to Cubist Pharmaceuticals' Cubicin, a similar product that generated $809 million in sales last year.

Merck announces a dividend boost and a new FDA approval
Last but not least, Merck announced yesterday that it was boosting its dividend from $0.43 to $0.44 per share -- not a major development, but still good news for income investors. The dividend will be paid on Jan. 8 to stockholders on record as of Dec. 16.

Merck also announced that the FDA had approved the 100 mg delayed-release tablet version of Noxafil, its treatment for fungal infections.