Summary
Plasma levels of diphenhydramine were determined by gas chromatography up to 34 h after oral administration of 50 mg to 6 healthy men. The antihistaminic activity of diphenhydramine was assessed by reduction in the area of wheals induced by intradermal injection of 5 µg histamine hydrochloride. The plasma level of drug and reduction in size of wheal were related in 4 of the 6 subjects, but not in the other two although all six had similar concentrations of the drug in plasma. In two experiments designed to measure psychometric parameters (number facility and a time evaluation test), no relationship was found between plasma levels of diphenhydramine and the performances of the subjects.
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Dedicated to Professor Dr. O. Eichler on the occasion of his 75th birthday.
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Bilzer, W., Gundert-Remy, U. & Weber, E. Relationship between antihistamic activity and plasma level of diphenhydramine. Eur J Clin Pharmacol 7, 393–395 (1974). https://doi.org/10.1007/BF00558213
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DOI: https://doi.org/10.1007/BF00558213