Source: Flickr user JD Hancock

As we head into the holidays, a few drugmakers will be hoping to unwrap FDA approvals in December. But not all approvals are created equal. According to McKinsey & Co most drugs tend to fall flat of preapproval forecasts. That suggests it's hard for investors to know which FDA approvals to embrace and which to ignore. So we asked three Motley Fool analysts to tell us what FDA decisions they're most interested in this month. Read on to learn which three they picked.

Brian Orelli: The only thing better than an instant blockbuster treating an unmet need is two drugs battling it out for those same patients.

We should have that soon when AbbVie (NYSE:ABBV) gets its hepatitis C drugs approved by the FDA in December. Enanta Pharmaceuticals will share in the wealth, having helped develop one of the drugs in the cocktail. The PDUFA date for the drugs is Dec. 21, but an approval could come early, especially if FDA reviewers want to clear their desks before the holidays.

While it's always possible the drugs might not get approved, it's highly unlikely. The cocktail is able to rid a vast majority of patients of their hepatitis C virus and appears safe enough to gain approval. The drugs were recently given a positive opinion from the European Committee for Medicinal Products for Human Use. Abbvie just has to wait on the rubber stamp approval from the European Commission before it can launch the drugs, which will go by Viekirax and Exviera, in Europe.

Once approved, Viekirax and Exviera will compete with Gilead Sciences' (NASDAQ:GILD) Harvoni. As a single pill taken once a day, Harvoni has the clear advantage over Abbvie's regimen, which requires two pills, one of which has to be taken twice a day. AbbVie might be able to capture some of the market share if it discounts its combination enough to get health insurers to make its cocktail the preferred (or perhaps only) hepatitis C drugs covered by the insurance plan.

Todd Campbell: Cubist Pharmaceuticals' (NASDAQ:CBST.DL) Zerbaxa may not be as highly anticipated as AbbVie's hepatitis C combo regimen, but it's an important drug that could significantly move the sales needle for this small cap biotech stock.

The FDA, which awarded Zerbaxa fast-track status last year, will make its decision on whether or not to approve Zerbaxa on Dec. 21. If the regulator gives Cubist the OK, the company thinks that Zerbaxa, a drug used to treat complicated urinary tract and intra-abdominal infections caused by gram negative bacteria, such as E. Coli, could have billion dollar blockbuster peak sales potential. That sales optimism stems from a rising number of gram negative bacterial infections globally. Since E Coli accounts for between 12% and 50% of hospital acquired infections annually, rising hospitalization tied to improving healthcare in developing countries and an ageing America suggests that the number of cases will continue climbing.

Cubist has also filed for EU approval and expects a decision from EU regulators in the second half of 2015. If Zerbaxa wins approval in the U.S. and EU and Cubist can deliver on Zerbaxa's billion dollar sales potential, it could prove to be a big win for the company given that it could help Cubist's sales almost double from their current $1.2 billion annualized rate. 

Leo Sun: POZEN (NASDAQ: POZN) investors are still waiting for the FDA to approve its "safer-aspirin" products PA32540 and PA8140 ("PA") as secondary prevention treatments for cardiovascular disease in patients with a high risk of developing aspirin-induced gastric ulcers.

POZEN stock has been on a bumpy ride over the past year, after the FDA rejected the approval of PA in late April due to "deficiencies" with a third-party supplier for an active ingredient in the drug. That was a setback for POZEN, but POZEN stated that the deficiencies were properly addressed, resubmitted its NDA, and now faces a new PDUFA date on Dec. 30, 2014. PA32540 previously met its primary and secondary endpoints in earlier clinical trials.

If PA is approved, it would be a big boost for POZEN, which reported $22.5 million in revenues in the first nine months of 2014. Most of the company's revenue, which rose 188% YOY to $7.5 million last quarter, currently comes from royalties for Vimovo, an anti-inflammatory arthritis drug which was passed from AstraZeneca to Horizon Pharma last year.