Study of Single and Multiple Doses of Inhaled AeroLEF (Liposome-Encapsulated Fentanyl)in Healthy Subjects

Inclusion Criteria: * Non-smoking male or female with a minimum age of at least 18 years * Body weight with aBMI range of 18.5 - 27, with a minimum weight of at least 60 kg. * Availability of subject for the entire study period and willingness to adhere to protocol requirements, as evidenced by a signed, written, Informed Consent Form. * Normal findings in the physical examination, vital signs (blood pressure between 100-140 - 60-90 mmHg, heart rate between 55-99 beats/min, respiration rate between 12-20 minute) and a 12 lead ECG. * Negative for drug abuse, nicotine, alcohol, hepatitis B-surface antigen, hepatitis C and HIV. * If a female of child-bearing potential, the patient must have a negative urine pregnancy test at screening and baseline. * No clinical laboratory values outside of the Principal Investigator's acceptable range, unless the Principal Investigator decided that the subject's values are not clinically significant. * Female subjects: (a) if pre-menopausal, have regular menstrual cycles (28-32 days), and (b) are not pregnant prior to study start and avoids pregnancy during the study and 1 month post drug administration, or (c) were surgically sterile for at least 6 months prior to enrollment, or (d) are post-menopausal for at least 1 year prior to enrollment. Exclusion Criteria: * Known history of hypersensitivity to fentanyl. * Presence or history of cardiac, pulmonary, gastrointestinal, endocrine, neuromuscular, neurologic, hematological, liver or kidney disease, or any condition known to interfere with absorption, distribution , metabolism, or excretion of drugs. * History of drug abuse or narcotic dependency. * Use of prescription medication within 30 days preceding entry int the study, including any enzyme inducing/inhibitory drugs (excluding contraceptives). * Participating in a clinical trial with an investigational drug within 30 days preceding this trial. * Blood donation within 45 days preceding this trial.