The acute hypnotic effects of hydroxyzine 25 mg and 50 mg nocte, were examined in six male and six female volunteers. Continuous electrophysiological measures (C-EEG) were taken to assess both nocturnal sleep and sleep tendency the following day. Both doses produced significant reductions in sleep onset latency and decreases in waking during sleep; reciprocal increases in sleep duration were also seen. Female subjects demonstrated a greater hypnotic response, including a dose-dependent decrease in sleep onset latency. Increases in sleep duration following both doses were significant for the female group alone. C-EEG measures of increased drowsiness the following day failed to achieve significance; although the largest effects on daytime sleepiness, including dose-dependent increases, were again seen with the female subject group and corresponded with subjective ratings. These results demonstrate the hypnotic efficacy of hydroxyzine, whilst failing to detect significant C-EEG hangover effects. However, variability in response to antihistamines, registered here as differences between the sexes, requires further consideration.

An extensive review of the literature was performed in order to identify those psychometric variables and conditions which have proved to be sensitive to the CNS effects of antihistamines. It is hoped that the result of this review will allow the formulation of a series of guidelines which would be useful both to researchers, when deciding on the methodology of future trials, and to readers when assessing the validity of a particular volunteer study with a antihistamine.

Twelve healthy volunteers were randomly allocated to receiving in a double-blind cross-over fashion levocabastine eye drops (0.5 mg/ml solution) and placebo. They were advised to instill 2 drops per eye, four times daily. Each treatment was administered for a period of 1 week. Before and after each treatment period psychomotor function was assessed using Critical Flicker Fusion Test and the Choice Reaction Time Test. At the same time intervals a subjective evaluation of sedation was given using a Visual Analogue of Sedation. Both objective and subjective measurements showed that no significant treatment effects could be detected. It is concluded that repeated instillations of levocabastine eye drops are devoid of any sedative side effects.

Forty-four patients, with symptoms of nasal obstruction, sneezing, itching and/or rhinorrhea, were entered into a placebo-controlled, double-blind study to evaluate the clinical efficacy of a topical antihistamine drug, levocabastine, applied 4 times a day for 14 days. At the end of the treatment the placebo patients were treated with levocabastine and the levocabastine patients were treated with beclomethasone dipropionate in a single-blind design for another 14 days. This study showed that levocabastine is significantly more active than placebo with reference to nasal discharge and sneezing. Placebo application improved the symptom score. Levocabastine could not be proved to be more effective against nasal obstruction than placebo in the double-blind trial. In the single-blind set-up, levocabastine resulted in an additional improvement in the score for obstruction, after the placebo period. Although the allergic group tended to respond better, no statistically significant difference could be detected between allergic and non-allergic patients. After treatment with levocabastine, beclomethasone dipropionate administration could not improve the results for nasal discharge and sneezing. For nasal congestion, beclomethasone dipropionate proved to be superior to levocabastine.

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