Analgesic and euphoric effects of high dose diazepam in schizophrenia.

Schizophrenics treated with high doses of diazepam (150-200 mg/day) showed marked analgesia besides certain antipsychotic effects. Euphoria was noticed in some of the patients. We hypothesized that influence on the endorphin metabolism might contribute to these clinical effects. Therefore, we measured pain threshold by three different methods before and during diazepam treatment. All patients exhibited a 1.5- to 2-fold increase of pain perception. Further, using a double-blind design, the opiate antagonist naloxone (30 mg i.v.) was administered. A significant decrease but not a complete block of the euphoric state and of analgesia was achieved. It is, therefore, concluded that other pharmacological properties of diazepam might be involved in the diazepam-induced euphoria and analgesia in man.