Pharmaceutical One of the USA's biggest drug distributor and health care services and information technology company, McKesson Corp (NYSE: MCK), has signed a definitive agreement to purchase all outstanding shares of closely-held US Oncology, a physician practice management company for oncologists, for cash. The total transaction, including the assumption of US Oncology's outstanding debt of about $1.6 billion, is valued at around $2.16 billion. 2 November 2010