Pilot Study of Pk 11195, a Selective Ligand for the Peripheral-Type Benzodiazepine Binding Sites, in Inpatients with Anxious or Depressive Symptomatology

PK 11195 is a selective ligand for the peripheral-type benzodiazepine binding sites which exhibits anti-conflict activity in animals. In a pilot open study, PK 11195 was administered to 10 psychiatric inpatients characterized by a rating of at least "moderate" for the item "felt loss of vitality" and a rating of at least "moderate" for the items "anxiety" and/or "inhibition of drive" from the psychopathological scale of the system developed by the Association for Methodology and Documentation in Psychiatry (AMDP). The duration of the study was two weeks, with an initial daily dose of 200 mg of PK 11195 which could be increased up to 400 mg. Patients were assessed weekly using the psychopathological and somatic AMDP scales and at days 0, 4, 7, and 14 using the Hamilton anxiety scale and a checklist of symptoms and side-effects. The results showed significant improvement in the AMDP factor scores related to somatic complaints, depression, anxiety, apathy-retardation, and psycho-organic symptoms. However, anxiolytic activity, confirmed on the Hamilton anxiety scale, remained moderate and reached maximum effect after one week. No side-effects, drowsiness in particular, were reported. This study therefore suggests a potential beneficial activity of PK 11195 on anxiety and inhibition, which merits further investigation in controlled studies.