Pharmacokinetic Evaluation of Intranasal Nalmefene Using Three Dosing Regimens

This study is to compare the pharmacokinetics (how the body absorbs, breaks down and eliminates drug from your body) of nalmefene when given as a single dose intranasally (IN;into the nose), as a single dose in each nostril and as two doses in one nostrils; and to evaluate the safety and tolerability of nalmefene IN.

Open-label, randomized, 3-period, 3-treatment, 6-sequence, ranodmised crossover study in 24 healthy volunteers. Subjects will be assigned to each of the 6 possible sequences. Each subject will receive 3 intranasal (IN) nalmefene doses: * 3mg IN dose (one 0.1mL spray of a 30mg/mL solution in one nostril) * 6mg IN dose (one 0.1mL spray of a 30mg/mL solution in each nostril) * 6mg IN dose (two 0.1mL sprays of a 30mg/mL solution in one nostril) There will be a 6 day washout period between doses. Screening can occur up to 28 days before admission, subjects will then stay in the inpatient facility for 16 days to complete the treatment phase of the study and will be discharged following completion of the discharge procedures at the end of the last period. Subjects will be called 3 to 5 days after discharge to inquire concerning Adverse Events (AEs) and concomitant medications since discharge.