| Abstract: | Fluradoline (HP 494), a tricyclic dibenz (b, f) oxepine derivative with an analgesic profile, was tested for antidepressant activity. After oral administration, fluradoline was twice as potent as imipramine and similar in potency to desmethylimipramine in blocking tetrabenazine-induced ptosis. Like standard antidepressants, fluradoline selectively increased response rates for electrical stimulation of the median forebrain bundle using internal capsule-lesioned rats. Response rates in nonlesioned rats were unaffected. There was partial protection against yohimbine toxicity and no potentiation of 5-hydroxytryptophan-induced seizures in mice. When administered to squirrel monkeys, the EEG profile from cortically-placed electrodes resembled that found for imipramine. Using in vivo and in vitro techniques, it was shown that fluradoline was not a monoamine oxidase inhibitor; however, the compound did block the reuptake of norepinephrine, serotonin and dopamine in brain homogenates. These results suggest that in addition to the analgesic profile, there is a concomitant antidepressant profile which may enhance the spectrum of activity of fluradoline. |
