A Dose Escalation Study of Intranasal Neuropeptide Y in Post Traumatic Stress Disorder (PTSD)

Inclusion Criteria: * Men and women, age 18-60. * Participants must have a level of understanding sufficient to agree to all tests and examinations required by the protocol and must sign a written informed consent document. We determine whether they have a sufficient understanding of the study procedures and risks by asking them to explain what's involved in the study and to give examples of study risks and benefits. * Participants must fulfill DSM-IV criteria for current PTSD, based on the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I) and on the Clinician-Administered PTSD Scale (CAPS). * CAPS score must be at least 40 (moderate PTSD severity) at screening. Exclusion Criteria: * Current, primary Axis I disorders other than PTSD. * History or current bipolar disorder or primary psychotic disorders (e.g. schizophrenia, schizoaffective disorder). * Current diagnosis of anorexia nervosa or bulimia nervosa. * Women who are pregnant or are breast-feeding. * Drug or alcohol abuse or dependence within the preceding 3 months. * poorly controlled hypertension (manifest by SBP \> 140 and/or DBP \> 90); HR \< 60 or \> 100 at rest at the time of screening and confirmed immediately prior to randomization * Evidence of coronary artery disease as evidenced by history, abnormal ECG, typical symptoms * History of arrhythmia, cardiac surgery, or family history of sudden death * Hepatic dysfunction as defined by AST and ALT \> 2x URL, or alkaline phosphatase and bilirubin \> 1.5 x URL within X days prior to randomization * Chronic renal disease as defined by serum creatinine \> 1.9 * Any other serious or unstable clinically significant abnormal findings of laboratory parameters, physical examination, or ECG as determined by the PI. * Any other serious or unstable condition that would put the subjects at undue risk as determined by the PI or additional safety monitor. * Serious and imminent suicidal or homicidal risk. * Psychotropic medication that will not be tapered off at least 7 days prior to screening; withdrawal symptoms must be absent at the time of screening * History of nasal disorders or sinonasal surgery, or significant nasal abnormalities based on nasal exam. * Received investigational intervention within 30 days prior to randomization