Sponsor elected not to conduct study at this time.

This study will compare the interactions of a placebo and two FDA-approved sleeping medications, Eszopiclone (Lunesta) and Zolpidem (Ambien), with certain chemical receptors in the brain. We want to show that we can use positron emission tomography images to measure the binding of these medications to the receptors.

We will enroll 4 normal, healthy, adult male volunteers who will undergo screening tests (labs, EKGs, medical history, physical exam, and MRI of the brain) for safety. If eligible, they will return for three separate positron emission tomography (PET) scans. Over the course of the three study visits, each subject will receive eszopiclone (Lunesta), zolpidem (ambien) and a placebo in random order.

After each medication or placebo dose, a PET scan will be done using a [11-C] flumazenil (Romazicon). The flumazenil will help us measure the binding of the study medications to chemical receptors called GABA receptors in certain parts of the brain.

Inclusion Criteria:

• Healthy Males age 18 to 35 inclusive
• Body Mass Index 18 to 30
• Willing to adhere to prohibitions and restrictions specified in protocol
• Must give informed consent.

Exclusion Criteria:

• Clinically significant abnormal lab values for chemistry, hematology or urinalysis at screening.
• Clinically significant abnormal physical exam, vital signs, or 12-lead EKG at screening
• Significant history of or current significant medical illness.
• Significant history of or current psychiatric or neurological illness or sleep apnea.
• Participation in another research study involving exposure to ionizing radiation within the last 12 months.
• Any clinically significant MR abnormality which may be relevant to the study.
• Metal implants which are relevant for MR or PET procedures or data.
• History of epilepsy or fits or unexplained blackouts.
• Serology positive for Hepatitis B surface antigen, Hepatitis C antibodies, or HIV antibodies.
• Positive urine screen for drugs of abuse.
• Positive alcohol screen.
• Known or suspected alcoholism or drug addiction even if currently abstaining
• Drinks on average more than 8 cups of coffee, tea, cocoa, or cola per day.
• Smoking cigarettes within 3 months prior to study drug administration.
• Clinically significant acute illnes within 7 days of study drug administration.
• Claustrophobia.
• Donation of 1 or more units of blood (approximately 450ml), or acute loss of an equivalent amount of blood within 90 days prior to study drug administration.
• Have received an experimental drug or used an experimental medical device within 90 days of planned start of treatment with drugs for this study.
• Use of any prescription or over the counter medication, or herbal medication (not including non-steroidal anti-inflammatory drugs) within 2 weeks of the first PET scan. Of particular concern would be GABA-ergic compounds and CYP3A4 inhibitors. Exclusion should also be considered if the subject has taken a drug with a long half-life (or of any metabolite) even if taken outside the two week time window. However, the subject can still be enrolled if, in the opinion of the investigator, such medication taken in that timeframe will not interfere with the results of the study.
• Psychological or emotional problems that would render the informed consent invalid or limit the ability of the subject to comply with the study requirements.
• Any condition that in the opinion of the investigator would complicate or compromise the study, or the well-being of the subject.