Thanksgiving is just a few short weeks away, but a few small drug companies are looking to give thanks for the Food and Drug Administration a little early. They all have PDUFA dates in the next week.

Double dose of pain-free PDUFA?
Cadence Pharmaceuticals (NASDAQ:CADX) is trying to get an approval for Acetavance, an intravenous version of acetaminophen -- the active ingredient in Johnson & Johnson's (NYSE:JNJ) Tylenol. The drug is already sold in the European Union by Bristol-Myers Squibb (NYSE:BMY), which should mean most of the safety issues have been worked through.

There's a large market for injected pain relievers, which are dominated by opioids that have unwanted side effects. The FDA even signaled as much by giving Acetavance a priority review. With a PDUFA date of the 13th, investors won't have to wait much longer to know if Cadence won its first drug approval.

On the other side of the weekend, NeurogesX (NASDAQ:NGSX) has a PDUFA date for Qutenza, its pain therapy patch. Qutenza contains caspacin, the compound in chili peppers that makes your mouth burn. A 60-minute application of the patch can provide up to three months' relief from pain caused by nerve damage in postherpetic neuralgia (PHN) patients. Of course, you've got to apply a local short-term painkiller first to deaden the burn from the caspacin, but it seems to do the trick.

The patch passed two phase 3 clinical trials in PHN patients, so an approval seems fairly likely. With any small biotech, the worry is often in the FDA finding an issue with manufacturing or quality control, which are less visible to investors than results from clinical trials. But that risk is somewhat diminished because the EU signed off on the patch earlier this year.

My bioreactor is bigger than your bioreactor
Orphan drug specialist Genzyme (NASDAQ:GENZ) hasn't been able to make enough of its Myozyme to keep up with demand. That's not a bad place to be, and the solution is simple enough: Get the FDA to approve making the drug on a larger scale.

Easier said than done.

The company had a PDUFA date last November, but the decision was pushed back after the FDA decided that the drug produced at the larger scale wasn't similar enough, and therefore required a different name: Lumizyme. Add in another delay, after a warning letter from the FDA because of problems with its manufacturing plant, and suddenly, a year has gone by.

The PDUFA day for Lumizyme is Saturday, so investors may hear about a decision on Friday. An approval seems likely, but then it seemed likely last year as well. With all the trouble that Genzyme has gotten itself into this year, an approval would go a long way toward getting Genzyme back into investors' good graces.

No guarantee of a decision
The FDA issues PDUFA dates based on the Prescription Drug User Fee Act, but the agency is under no obligation to make sure it hits the target date. Delays -- announced or otherwise -- can and do happen.

Take Xenoport (NASDAQ:XNPT) and GlaxoSmithKline's (NYSE:GSK) gabapentin enacarbil. The duo was supposed to hear a decision about their drug for restless leg syndrome on Monday, but the FDA pushed the decision back by three months because the companies submitted information about risk evaluation and mitigation strategy (REMS) that the FDA didn't have time to evaluate before the PDUFA date.

Trading on these dates might seem like a great way to make a quick buck -- the smash-and-grab version of investing -- but getting in and out quickly depends on a finicky FDA. If you're interested in investing because you think the drug is a good one, my advice is to buy now and don't worry about any delay in a decision. It may seem like the FDA is on a never-ending holiday, but it eventually gives responses to all the applications it accepts.