Cariporide is a sodium/hydrogen ion exchange inhibitor under development by Aventis Pharma, formerly Hoechst Marion Roussel (HMR), as a potential treatment for myocardial infarction (MI), ischemic damage due to angioplasty and reperfusion following thrombolysis. It is in phase II/III trials [221118]. Cariporide inhibits the interchange of sodium ions and protons in myocardial cells during unstable angina or MI when cells metabolize anerobically. This prevents lactic acid production and an increase in calcium levels which causes cardiac arrhythmias and heart tissue death [253616]. Approval filings in the US and EU had been scheduled for the second half of 1999 [309323]. In 1998, HMR expected that the drug would be launched in 2000, and would have a potential market in excess of DM 750 million [288651]. By May 2000, however, the launch date had been revised for between 2003 and 2004 [370971], [379336]. Aventis is expecting peak sales to be around $400 million [333420]. In March 1999, HMR reported that trials for MI had been suspended after results from the phase III GUARDIAN trial did not achieve statistical significance [353173]. In August 2000, however, a phase II trial in patients with acute MI was underway [379051]. A phase III trial in patients undergoing coronary artery bypass grafting (CABG) was expected to begin in early 2000 after the results of ongoing dose-optimization studies in CABG patients are known. As of May 2000, however, this trial had not begun, although based on promising CABG-related results of the GUARDIAN trial, the phase III trial in this indication is expected to begin in the first half of 2001 [370971]. There were also plans for the initiation of European phase II trials in acute MI patients; similar phase II trials are ongoing in Japan. In September 2000, Merrill Lynch predicated launch in 2003 [383742]. In February 1999, Lehman Brothers predicted a 70% probability that cariporide would reach market in the US/Europe and 50% probability that it would reach the Japanese market. They also predicted a US/European launch in 2000 with peak sales of $400 million in 2008 and a Japanese launch in 2002 with peak sales of $100 million [319225].