Biochemical and clinical assessment of histamine blockade.

The effects of antihistamines on biochemical stress indicators and on psychomotor and physiological functions were studied in 60 healthy patients receiving in a randomized, double-blind study either 25 mg promethazine, 150 mg ranitidine, both drugs or placebo (n = 15 in each group). Different aspects of the premedications were evaluated by determining various hormone, neurotransmitter and neurotransmitter metabolite levels in blood and cerebrospinal fluid, and subjectively using questionnaires concerning the quality of the preoperative night's sleep and visual analogue scales, and objectively by measuring changes in blood pressure and heart rate, impairment of vigilance with the Maddox wing apparatus and the critical flicker fusion threshold test. The relationships between the subjective assessments and the biochemical stress indicators were also investigated. There were no differences between the study groups in the quality of the preoperative night's sleep, estimated fear, apprehension or dizziness, or in the various physiological stress indicators. Only few statistically significant correlations were found between the subjective and biochemical assessments. It is concluded that histamine receptor antagonists used in clinical doses do not interfere with the biochemical, clinical preoperative, and physiological responses.