The clinical pharmacology of viloxazine hydrochloride-a new anti-depressant of novel chemical structure.

1 The clinical pharmacological properties of viloxazine hydrochloride (ICI 58,834, Vivalan), a new antidepressant of novel chemical structure, have been investigated in a series of double-blind randomized studies comparing it with placebo and imipramine. Throughout the studies, viloxazine hydrochloride was given in single doses of 100 mg (expressed as base), and imipramine hydrochloride was given in single doses of 50 mg (expressed as salt). 2 The effect of viloxazine upon the following parameters was measured: pulse rate, blood pressure, forced expiratory volume, reaction time, critical flicker frequency, salivary flow, pupil size and palpebral fissure size. In addition, the possible interaction between viloxazine and alcohol was investigated using measurements of reaction time. 3 Both viloxazine and imipramine produced a transient tachycardia, but no consistent effect on blood pressure was seen. Neither drug had any effect upon forced expiratory volume. 4 The differences that emerged between viloxazine and imipramine were that viloxazine depressed critical flicker frequency whereas imipramine did not, and imipramine prolonged reaction time whilst viloxazine did not. Imipramine reduced salivary flow and increased the size of the pupil and palpebral fissure. Viloxazine did neither. 5 Imipramine was shown to potentiate alcohol whereas, at the doses used, viloxazine did not. 6 It is concluded that viloxazine appears to have less anticholinergic and possibly less sympathomimetic properties than imipramine. It is also concluded that viloxazine, unlike imipramine, does not potentiate alcohol.