After spending a solid six months at a less-than-impressive three-star rank, Arena Pharmaceuticals (Nasdaq: ARNA) has impressed enough top-performing members of our 160,000-strong Motley Fool CAPS community to climb its way back up to four stars, out of five possible. What's changed?

Let's find out by tapping into CAPS to view the analysis and commentary posted by the 568 members who have given their opinion on the biopharmaceutical firm.

Arena Pharmaceuticals is still a development-stage company, but more CAPS members are taking a bullish position as it gets closer to the possibility of bringing its key weight-loss drug, lorcaserin, to market. Arena's drug is competing against development-stage weight-loss therapies Qnexa from VIVUS (Nasdaq: VVUS) and Contrave from Orexigen Therapeutics (Nasdaq: OREX). Each is awaiting approval and has a chance to tap a huge market, with Qnexa so far showing the best effectiveness in clinical trials.

The Food and Drug Administration is expected to complete its application review of lorcaserin later this year and CAPS members like its chances of approval.

Larger drug companies Pfizer (NYSE: PFE), Merck (NYSE: MRK), and sanofi-aventis (NYSE: SNY) have come up short in their attempts at the weight-loss drug market, when side effects like depression and suicidal thoughts proved to be too prevalent. Abbott Labs' (NYSE: ABT) current treatment, Meridia, has run into heart-related safety issues with certain patients.

But some CAPS members think lorcaserin will be seen as a safer choice for patients and like its market potential. Arena wants to find a marketing partner before an FDA decision is reached, but is also preparing to launch the drug on its own if necessary.

Arena has other drugs in its pipeline, all of which are in the early phases of clinical trials. Some CAPS members recognize the speculative nature of the stock and its potential for high volatility, but also recognize that obesity is becoming a huge problem in the U.S., an issue that could improve the odds of FDA approval. And given the large potential market, the upside potential for lorcaserin is too tempting to pass up for many investors.

Do you think Arena Pharmaceuticals deserves its raised status? Add your thoughts in the comments box below on this page, or head over to CAPS to rate the company.

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Fool contributor Dave Mock recently upgraded his bedding with some new, fluffier pillows. He owns shares of Pfizer, which is an Inside Value selection. The Fool's disclosure policy shouldn't be required to perform an eye exam to receive a driver's license.