Shortages of prescription drugs nearly tripled from 2005 to 2010 and reached record levels in 2011 as manufacturers ceased operations or ran into production problems. In some cases, lifesaving treatments have been delayed, sending patients on desperate searches for needed medicines, doctors say. Shortages have also caused injuries from mistakes and at least 15 deaths around the country since mid-2011, according to the Institute for Safe Medication Practices. Shortfalls are so common that pharmacy staffers at hospitals are spending many extra hours to ensure an uninterrupted flow of medicine to cancer patients, victims of heart attacks and accidents, and a host of other ill people.