The vasorelaxant effect of dipyrone on an experimental cerebral vasospasm model in rabbits.

Cerebral vasospasm is an important clinical phenomenon associated with a high mortality rate and therefore any promising findings in the laboratory deserve assessment in clinical practice. Dipyrone (Metamizol) has been in clinical use for its non-narcotic analgesic effect since 1922. In addition to its analgesic effect, dipyrone has been shown to possess spasmolitic activity in various smooth muscle organs. In our recent study, it was shown that dipyrone also has a relaxing effect in vascular smooth muscle preparations and that the smooth muscle relaxing effect on the rabbit thoracic aorta was produced by one of dipyrone's spontaneous degradation products. The present study was designed to examine the possible effects of dipyrone on the rabbit basilar artery in a model of cerebral vasospasm. Dipyrone was shown to have a clear spasmolitic effect in the rabbit basilar artery vasospasm produced by an intracisternal injection of autologous blood. This effect was apparent with either local or intravenous administration of dipyrone. These data suggest that dipyrone is potentially useful in the treatment of patients suffering from cerebral vasospasm in combination with other agents or alone.