Pharmacokinetics of Oxycodone and PF614 Co-Administered with Nafamostat (PF614-MPAR-101)

This is a single center, randomized, open-label formulation development study for the nafamostat formulation (IR solution and/or ER prototype capsules) and will have the option to assess the effect of food on a selected formulation of healthy subjects. Parts 1 and 2 are planned to enroll a total of 64 healthy subjects, with roughly equal number of males and an even number of females with roughly equal number of males and females in each cohort if possible. Subjects will be randomized to regimen stratified by gender prior to first dose. Cohort 1 and Cohort 6 will consist of 8 subjects who will receive dosing on two occasions in a 2-period sequential design. Cohorts 2 to 5 and Cohorts 7 to 10 will consist of 6 subjects in each cohort and they will receive dosing on a single occasion only. Cohorts 2 to 5 and Cohorts 7 to 10 can be dosed in parallel after Cohort 1 dosing. Part 1 (with naltrexone blockade) and Part 2 (without naltrexone), Cohorts 1-10, were later expanded to include 6-13 subjects each. In Cohort 1 and Cohort 6, subjects will receive the PF614 solution alone and concomitantly with nafamostat. In addition, prior to and following each regimen in all periods, subjects will receive blocking doses of the opiate antagonist naltrexone to reduce the opioid-related side effects. Interim reviews of the safety and PK data for oxycodone and PF614 to 48h post-dose will take place after Cohorts 1 and 6, Cohorts 2 and 7, Cohorts 3 and 8 and Cohorts 4 and 9 to decide upon the following: nafamostat formulation to dose in the subsequent period; After Cohorts 3 and 8 only: The prandial status (fed vs fasted) for Cohort 4 and Cohort 9. Extended-release prototype capsule formulations will be selected from a 2-dimensional design space describing formulation variables for release rate and dose; however the maximum nafamostat dose to be administered with be 10 mg. Part 3 (N=12 subjects) was added as a 7-period open-label cross-over study to assess the selected combination of nafamostat IR solution and/or ER prototype capsule(s) identified from Part 2 who were administered with PF614 solution at increasing dose levels to simulate overdose. All subjects in Part 3 received naltrexone blockade.