The effects of atenolol (tenormin) and methyldopa on simple tests of central nervous function.

Two identical studies, one comparing the effect of single doses of a new beta-adrenoceptor blocker, atenolol (Tenormin) (50 mg and 100 mg) and placebo, and the other comparing the effect of single doses of methyldopa (250 mg and 500 mg) and placebo, in healthy volunteers, were carried out. 2 In both studies the effect of the drugs upon reaction time, critical flicker frequency, subjective drowsiness, pulse rate and blood pressure was measured. 3 Atenolol produced no effect upon reaction time, critical flicker frequency or subjective feelings, while methyldopa produced a statistically significant prolongation of reaction time and a statistically significant increase in the subjective sensation of drowsiness. 4 Atenolol produced statistically significant reductions in systolic and diastolic blood pressure and in pulse rate while methyldopa was without effect. 5 It is concluded that atenolol is unlikely to produce the side effects of sedation or drowsiness.

Blood level studies with viloxazine hydrochloride in man.

1 The pharmacokinetic characteristics of a new antidepressant, viloxazine hydrochloride, (ICI 58,834, Vivalan), have been investigated in four separate studies. 2 In Study 1, blood levels were measured over a period of 24 h after single doses of viloxazine hydrochloride from 10-100 mg (expressed as base). In Study 2, blood levels were measured over 24 h, during which three single doses of viloxazine hydrochloride (80 mg, expressed as base) were given 4 h apart. In Study 3, blood samples and urine and faeces were collected for 96 h after doses of 40 and 100 mg of [14C] viloxazine hydrochloride (40 muCi). In Study 4, 1 h blood levels were measured at weekly intervals during a comparative clinical trial in which viloxazine was given at a dose of 100 mg four times a day. 3 The half-life of the drug is in the range 2-5 h with maximum blood levels occurring in 1-4 h of the oral dose. Maximum blood levels are proportional to the oral dose given over the range studied (0.76(mug/ml)/(mg/kg)). The drug is very well absorbed orally, only 2% being found in faeces. Repeated dosing at 4 hourly intervals leads to slightly higher blood levels after the second, but not subsequent, doses. No accumulation was seen from week to week in depressed patients. No regular sex difference was seen in the pharmacokinetic characteristics of viloxazine hydrochloride but two females in one study did show a markedly higher maximum blood level and apparently longer half-life than the males. 4 It is concluded that viloxazine is rapidly and almost totally absorbed after an oral dose, and has a shorter half-life than the tricyclic antidepressants; therapy with it should be easily controllable.

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.