Viagra challengers will reach the domestic market

Business sources say that the domestic anti-impotence drugs market, which has been predominated by Pfizer's Viagra, will emerge as an arena of fierce competition among four pharmaceutical firms, Eli Liily' Cialis (tadalafil) and Levitra (vardenafil) will be launched during the latter half of this year.

Cialis, which is likely to be launched in Korea on oncoming July this year, has been init...