In the world of pharmaceuticals, there's nothing like the launch of a new, promising drug to get an investor's heart pumping. With regulatory approval in hand, the early work is over: In launching, companies face the new obstacle of delivering on the hype and translating potential blockbuster drugs into cold, hard sales figures.

The Food and Drug Administration's been hard at work approving new drugs over the past year, and companies from big pharma to small biotechs are ready to capitalize. Here are three drug launches you'll need to keep an eye on throughout 2013.

Big pharma's big win
Big pharma has recently been abuzz about anticlotting agent Eliquis from Pfizer (NYSE:PFE) and Bristol-Myers Squibb (NYSE:BMY). The drug gained approval only just before the end of last year, but clearing that regulatory hurdle could lead to huge gains for Pfizer and Bristol.

Launches mean less for such well-diversified companies as these, but Eliquis could still make a giant impact. Atrial fibrillation -- the disorder that Eliquis has been approved to combat stroke risk for -- affects millions of patients in the U.S. alone. The market to replace the disorder's standard treatment, warfarin, is expected to grow to billions of dollars in coming years; one analyst has already stated expectations of Eliquis hitting peak sales of $4.2 billion later in the decade. That's a number you can't ignore, even when taken in context of big pharma's massive annual sales.

Eliquis will have to fight against two competitors already on the warfarin-replacement market -- Xarelto and Pradaxa -- but Bristol-Myers Squibb has already noted that only Eliquis has shown significant advantages over warfarin in reducing risk of numerous symptoms of atrial fibrillation, such as stroke, major bleeding, and -- yes -- death.

The drug's even more important when you consider the recent fortunes of these two companies. Pfizer had a standout 2012, but sales of Lipitor keep dropping fast -- down more than 50% last year. With other major drugs, such as Prevnar 13 and Prevenar 13, also seeing sales declines, the success of Eliquis will establish a major building block for the future. For Bristol-Myers Squibb, which took a $1.8 billion hit after it dropped hepatitis-C drug BMS-986094, Eliquis living up to its hype would do wonders to set the company back on track.

Charting the future with Gattex
NPS Pharmaceuticals' (NASDAQ: NPSP) Gattex isn't quite on the same level as Eliquis, but it's no less important for investors of this small biotech.

Gattex is designed to combat short-bowel syndrome, or SBS, a disorder that interferes with the body's ability to take in nutrients. As SBS affects only around 10,000-15,000 American adults severely enough to require feeding through an IV line (and thus be eligible for Gattex), NPS won orphan-drug designation for its product. There's precious little competition out there for Gattex; treatment options such as Zorbitive and NutreStore aren't pressing concerns for NPS, and each has been around since at least 2004.

Though the FDA's recent approval doesn't necessarily mean billions of dollars of revenue headed NPS's way, the company's CEO did mention that peak sales of Gattex could rise to $350 million. Considering that NPS doesn't have anything else out on the market right now, getting this drug out will put the company on solid ground.

NPS currently relies on royalties and sales of royalties for other medications for its revenue. Gattex's sales would allow the company to focus on its future, where it has another orphan  drug -- Natpara for hypoparathyroidism -- waiting in the wings.

Ariad's leukemia solution
Investors in Ariad Pharmaceuticals (NASDAQ: ARIA) have plenty to celebrate in the new year as well. Last month's FDA approval of leukemia-busting drug Iclusig -- a name that sounds more like a rare fungus than an important, promising drug -- has Ariad poised to make a name for itself in a competitive market.

Iclusig's real potential comes in its ability to treat patients who aren't responding to other treatments for chronic myeloid leukemia, or CML. While the CML market already boasts Novartis(NYSE:NVS) legendary blockbuster drug Gleevec -- as well as successors such as Tasigna and Sprycel -- Ariad's recently approved drug could be a major hit. Gleevec's a monster in its own right; Novartis' product (known as Glivec in some markets abroad) recorded more than $4.6 billion in sales in 2011. But Iclusig's potential to help patients who have already shown resistance to treatment from Gleevec (around 20%-30% of patients) nets Ariad a nice market straight off the bat.

The drug likely won't see seven-digit annual sales like Eliquis, but Iclusig's ceiling is high. Peak sales estimates vary, but the $800 million annual figure is often thrown around. That's more than enough for Ariad and its shareholders, considering that the company's banking its success on this promising drug. And promising it is -- Iclusig struck a home run in clinical trials of patients who had already tried one of the three other drugs and showed resistance to treatment, and it's also under review in Europe. Ariad's got a couple of other drugs in the pipeline, but Iclusig's rollout is the one investors need to watch with a close eye.

A year to remember
Eliquis may be the biggest -- and most profitable in the future -- of the three, but all these drugs mean big things for their companies. Ariad and NPS have staked their futures on Iclusig and Gattex, respectively, and the success of these drugs will pave the way for future triumphs from each company. While Pfizer and Bristol-Myers Squibb have less to gain from Eliquis, each company is in need of a feel-good moment -- and this ballyhooed drug's launch could provide a foundation for the future each has been looking for. Keep your eyes open in 2013, because these three drugs are ready to make waves.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.