Oxycontin releases oxycodone slowly and continuously over 12 hours and only needs to be given twice a day. Oxycodone is shorter-acting, with an average half-life of 3.2 hours, which means that half the dose of oxycodone is eliminated in 3.2 hours, which is why it is usually given four to six times a day to provide all-day pain relief. More @Wikipedia
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