was replaced as CEO and chairman by Paul Clark, a former executive at Abbott Laboratories. A former Icos manager named short-sighted leadership by Clark as a factor in the failure of the company to develop any other successful drugs apart from Cialis. Cialis Sold as Cialis and initially codenamed IC351, tadalafil is a drug prescribed for erectile dysfunction (ED) and approved for pulmonary arterial hypertension (PAH). It is a phosphodiesterase type 5 (PDE5) inhibitor, similar in function to sildenafil. In addition to ED and PAH, tadalafil has undergone clinical trials for the treatment of benign prostatic hyperplasia and for female sexual dysfunction. Tadalafil was initially formulated by Glaxo Wellcome (now GlaxoSmithKline) under a new drug development partnership between Glaxo and Icos that began in August 1991. The drug was originally researched as a treatment for cardiovascular diseases such as hypertension and angina, but focus quickly shifted to ED with the success of another PDE5 inhibitor, sildenafil (Viagra), which had been developed by Pfizer. Icos began research on tadalafil in 1993, and clinical trials started two years later. Glaxo let the partnership with Icos lapse in 1996, including the company's 50% share of profits from resulting drugs, because the drugs in development were not in Glaxo's core markets. In 1998, Icos formed a 50/50 joint venture with Indianapolis-based Eli Lilly (Lilly Icos LLC) to develop and commercialize tadalafil as Cialis. The release of Cialis in the United States was delayed in April 2002 when the Food and Drug Administration (FDA) recommended that Icos perform more studies, improve labelling, and address manufacturing issues. Cialis was approved in Europe in November 2002 and in the United States a year later. The drug was approved for once-daily use for ED in Europe in June 2007 and in the United States in January 2008. In 2006, Cialis generated $971 million in sales, leading Icos to post its first-ever quarterly profit in August. In May 2009, tadalafil, to be sold as Adcirca by United Therapeutics, was approved in the United States for the treatment of pulmonary arterial hypertension based on data from a pivotal study begun before the sale of Icos to Eli Lilly. Lawsuits with Pfizer Pfizer and Lilly Icos have filed many lawsuits against each other in various countries over Cialis and Viagra. Pfizer was given a broad patent on PDE5 inhibitors in Britain in 1993. Lilly Icos filed a complaint in a London