VIVUS (NASDAQ:VVUS) has been plodding along over the past decade, but after a pair of successful clinical trials for its weight-loss drug, Qnexa, the company is now getting some good clinical trial data for erectile-dysfunction drug avanafil.

In a phase 3 trial, avanafil was able to help men have erections and "successful intercourse" better than placebo. Most importantly, avanafil seems to work in just 30 minutes, faster than the onset of Pfizer's (NYSE:PFE) Viagra, Eli Lilly's (NYSE:LLY) Cialis, and Merck (NYSE: MRK), GlaxoSmithKline (NYSE: GSK). and Bayer's Levitra.

As you can imagine, spontaneity is a huge selling point for erectile-dysfunction drugs. Cialis has a daily dosing form that removes the need to plan ahead, but that can be expensive for men who aren't lucky enough to need it that often.

VIVUS already has an erectile-dysfunction drug, Muse, on the market, but it hasn't inspired many sales -- just $9.7 million through the first nine months of the year. To compete, VIVUS is going to have to find a large-pharma partner willing to shell out big bucks for the direct-to-consumer advertisements required to compete with the little blue pill and Cialis' "When the moment is right" campaign. I can already see the advertisement: two empty bathtubs with the caption, "The time was right now."

VIVUS has plenty of time to find that partner: avanafil is being tested in two additional efficacy trials as well as a follow-on safety trial, which won't report results until late next year. That would put an approval sometime into 2011, when we should expect VIVUS' stock to improve.