Assessment of the Effect of Naltrexone on Lofexidine Single Dose Pharmacokinetics in Healthy Subjects

Lofexidine HCl (two 0.2 mg tablets) will be administered as a single oral dose (0.4 mg) on Day 1 and on Day 11.Commercially available naltrexone HCL tablets will be administered as a single oral 25 mg dose on Day 4 and as a single oral 50 mg dose on Days 5 through 13. On Day 11 administration of both naltrexone and lofexidine will occur. Dose administration times for each drug are to be standardized for all treatment days. The scheduling of the naltrexone dose is to be standardized so that the naltrexone dose is administered 2 hours after the lofexidine dose on Day 11 when both drugs are administered.