The historical progress of Cialis:

•  1993: Pharmaceutical co. ICOS started its research on a compound IC351 that inhibits the PDE5 enzyme.

•  1994: Icos receives its first patent on IC351.

•  1995: First phase of clinical trials begun.

•  1997: Icos conducted the first study in patients with erectile dysfunction problem.

•  1998: Icos and Eli Lilly and Co. form a joint venture to commercialize drugs for the treatment of sexual dysfunction.

•  1999: Phase III clinical studies begin on IC351.

•  2001: New drug application is filed with the U.S. Food and Drug Administration for IC351. The company renames the drug Cialis.

•  April 2002: FDA reviews drug application, saying the company must complete more clinical studies, resolve manufacturing issues and complete labeling.

•  November 2002: Cialis gets European approval.

•  February 2003: Marketing of Cialis begins in Europe.

•  21st November 2003: US FDA approves Cialis in the United States for usage.

•  December 2003: Cialis is likely to be available for sale from December.

•  January 2004: Made available to buy Cialis in the USA.