Fear of government action against healthcare providers who prescribe opioids is a contributing factor to the under-treatment of chronic pain.¹ There is a demand for products with reduced abuse liability.² One such formulation under development includes polymer-coated extended-release morphine sulfate (P-ERMS) surrounding a sequestered core of naltrexone, an opioid antagonist that competes at the opioid receptor sites. The product is designed to release naltrexone if product tampering occurs by crushing, chewing, or dissolving. Morphine pharmacokinetics of this formulation were assessed in this single-dose, open-label, two-period crossover study (fasted and fed) in eight healthy subjects aged 21 to 45 years. After an overnight fast, subjects either received study drug (containing 60-mg morphine sulfate) or consumed a standard high-calorie, high-fat breakfast and took the dose 30 minutes later. Blood samples for morphine pharmacokinetic analysis were drawn prior to dosing and at intervals from 0.5 to 168.0 hours postdose. For the 60-mg morphine dose, C_max was 10.70 ng/mL fasted and 9.18 ng/mL fed. AUC_inf was 260.6 hr*ng/mL fasted and 246.0 hr*ng/mL fed. The T_max for morphine was 7.50 hours fasted and 8.75 hours fed, consistent with a sustained-release profile and with current prescribing information for P-ERMS.³ Adverse events, reported in five subjects, were either mild or moderate in intensity, and resolved. Study results demonstrated that the release characteristics of morphine in this formulation containing a sequestered naltrexone core were similar to characteristics demonstrated in previous studies of P-ERMS. The study formulation was well tolerated. (¹Jung B, Pain Med, 2006; ²Wright C, Drug Alcohol Depend, 2006; ³KADIAN® [package insert]. Piscataway, NJ: Alpharma Branded Products Division Inc.)