Performance-enhancing drugs will come to the fore at Sunday's US Super Bowl -- but off the field rather than on it.

Two recently launched anti-impotence drugs have snapped up ad slots during coverage of the game as they try to carve out a share of the rapidly growing, billion-dollar sector.

Levitra, launched in September, and Cialis, out since November, will target the game's 90 million viewers in a bid to stiffen the competition against the market leader owned by Pfizer [the name of which cannot be printed here for fear of spam filters -- but needless to say, it rhymes with Niagara].

Pfizer has not yet announced whether it will retaliate by buying a Super Bowl spot of its own. There are signs its brand is coming under pressure: despite $50 million (€40m; £28m) of marketing spend last year, its share of new prescriptions tumbled almost 20%.

Levitra is marketed by GlaxoSmithKline and Bayer, while Cialis is backed by Eli Lilly and ICOS. Their ads are unlikely to be typical Super Bowl fare, as they are subject to strict regulatory obligations; nevertheless, the game gives them a good opportunity to take on Pfizer.

"It's a very large category with very large potential," commented Douglas Stayman, professor of marketing at the Johnson Graduate School of Management at Cornell University. "Even though the category is not a Super Bowl category, the event makes a lot of sense because the Super Bowl is a great place to introduce new products."

Data sourced from: USA Today; additional content by WARC staff