Abstract
An oral test dose of diazepam was given to 25 anxious neurotics before they received three weeks of treatment with the drug. Blood was taken at 1 h and 2 h after the test dose (and during subsequent treatment) and the plasma levels of diazepam at these times were assayed. Ratings to assess subsequent clinical response were made in the context of a double-blind trial.
The 2 h plasma level correlated positively with the steady-state plasma level of diazepam after one week of treatment.
There was a statistically strong link between a low 2 h plasma diazepam level and improvement after the first week of treatment. This correlation of low pretreatment plasma level with good response suggests either that there may be an avid uptake of diazepam from the blood in those who are going to improve clinically as a result of its administration, or that good responders have a special ability to form active metabolites of diazepam.
A high 2 h plasma level was found in those patients who reported increased tiredness during the three weeks on diazepam.
The 1 h plasma diazepam level, in contradistinction, had but negligible correlations with steady-state levels, with clinical response and with diazepam-induced tiredness.
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This study was carried out at Prince Henry Hospital, Sydney. The principal author was then a research fellow of the School of Psychiatry, University of New South Wales with a grant from Pfizer, Australia Ltd. The chromatography was performed in the Department of Pharmacology, University of Melbourne, Parkville, Victoria.
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Bianchi, G.N., Fennessy, M.R., Phillips, J. et al. Plasma level of diazepam as a therapeutic predictor in anxiety states. Psychopharmacologia 35, 113–122 (1974). https://doi.org/10.1007/BF00429578
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DOI: https://doi.org/10.1007/BF00429578