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Interindividual variation of serum haloperidol concentrations in Japanese patients – clinical considerations on steady‐state serum level–dose ratios
Author(s) -
Yukawa E.,
Ichimaru R.,
Maki T.,
Matsunaga K.,
Anai M.,
Yukawa M.,
Higuchi S.,
Goto Y.
Publication year - 2003
Publication title -
journal of clinical pharmacy and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.622
H-Index - 73
eISSN - 1365-2710
pISSN - 0269-4727
DOI - 10.1046/j.1365-2710.2003.00460.x
Subject(s) - concomitant , haloperidol , medicine , cyp2d6 , anesthesia , pharmacokinetics , pharmacology , cytochrome p450 , metabolism , dopamine
Summary Objective: Marked interpatient variability in haloperidol (HAL) level–dose (L/D) ratios makes it difficult to use the administered dose for predicting serum concentrations. Objective: To investigate the effect of dose, age, total body weight and co‐medication on steady‐state HAL L/D ratios. Method: Retrospective analysis of dose and HAL blood level data from 168 patients. Results: The HAL L/D ratio decreased curvilinearly with increasing daily dose of HAL. The patients treated with concomitant antiparkinsonian drugs showed a mean HAL L/D ratio that was 24·9% higher than those without antiparkinsonian drugs. The patients treated with concomitant antiepileptic drugs showed a mean HAL L/D ratio that was 27·2% lower than those without antiepileptic drugs. The mean HAL L/D ratio of patients treated with concomitant CYP2D6 substrates was not significantly different from those without CYP2D6 substrates. Conclusion: There is a wide interindividual variability in blood levels of HAL in patients given the same dose. Routine monitoring of HAL serum level is useful, especially in patients who require associated antiepileptic and/or antiparkinsonian medication.