CNS effects of histamine H-1 antagonists

An accurate evaluation of the functions of the human brain during the admin istration of drugs is one of the most complex tasks in medical science. In the case of H-1 antihistamines, there are many biases that can explain why the interpretation of pharmacological data and those from clinical studies can be very difficult. First of all, the allergic disease itself may modify central nervous system (CNS) functioning and effective medical treatment m ay accordingly influence the self-reported CNS sensations of patients. More over, the carefully selected populations that are enrolled both in pharmaco logical and clinical studies do not reflect the profile of patients who are trreated with such drugs on an everyday basis. Finally, studies of perform ance impairment and those relying on self-reported sensations may give diff erent and indeed conflicting results. It may be concluded that the various pronouncements on the CNS properties of H1 antihistamines must be treated w ith some caution.