Oxycodone has a half-life of 4.5 hours. It is available as a generic medication. Its manufacturer Purdue Pharma claimed in their 1992 patent application that the duration of action of OxyContin, oxycodone's controlled-release preparation, is 12 hours in "90% of patients." It has never performed any clinical studies in which OxyContin was given at more frequent intervals. In a separate filing, Purdue claims that controlled-release oxycodone "provides pain relief in said patient for at least 12 hours after administration." However, in 2016 an investigation by the "Los Angeles Times" found that "the drug weans off hours early in many people," inducing symptoms of opiate withdrawal and intense cravings for OxyContin. One doctor Lawrence Robbins told journalists that over 70% of his patients would report that OxyContin would only provide 4–7 hours of relief. Doctors in the 1990s often would switch their patients to a dosing schedule of once every eight hours when they complained that the duration of action for OxyContin was too short to be only taken twice a day.