Substance P Antagonist in the Treatment of Posttraumatic Stress Disorder

This study, conducted at the NIH and the Mount Sinai School of Medicine, will examine the effectiveness of a substance P or NK1 antagonist study drug known as GR205171 in treating the symptoms of posttraumatic stress disorder (PTSD). People between 18 and 65 years of age who have been diagnosed with PTSD may be eligible for this study. Participants undergo the following tests and procedures: Treatment: Patients are tapered off current ineffective medications over 1 to 2 weeks. All participants receive placebo (sugar pill) at the start of the study. At some point within the first 3 weeks of the study, they are then randomly assigned either to take GR205171 or to continue with placebo for the remainder of the 10-week treatment period. Clinic visits: Patients come to the clinic once a week during treatment. The following procedures are done at various visits. * Interviews, self report questionnaires and psychiatric rating scales at every visit. * Physical examination, blood and urine tests. Blood is drawn up to 10 times during the study. Follow-up visits continue for up to 3 months after the end of the study, during which patients are offered standard clinical treatment.