Coprescription of paroxetine with tamoxifen to reduce hot flashes reduced plasma 4-hydroxy-N-desmethyl-tamoxifen plasma concentrations in a CYP2D6-dependent manner

D. A. Flockhart, D. F. Hayes, J. M. Rae, P. Bhargava, A. Morocho, V. Stearns

Research output: Contribution to journalArticle

Abstract

Paroxetine is often prescribed to reduce hot flashes and improve compliance in patients treated with tamoxifen. To test the hypothesis that paroxetine or CYP2D6 genotype might alter tamoxifen metabolism to active metabolites we measured the drug and 3 metabolites in patients treated during chronic tamoxifen treatment. Thirteen women prescribed chronic tamoxifen (20 mg po qd) were co-prescribed paroxetine (10 mg po qd) for the treatment of hot flashes. Genotype for CYP2D6 was determined and plasma concentrations of tamoxifen and 3 metabolites: N-desmethyl-tamoxifen (X), 4-hydroxy tamoxifen (B) and 4-hydroxy-N-desmethyl tamoxifen (BX) were determined by LC with on line derivatization and fluorescence detection after 4 weeks of paroxetine treatment. Neither paroxetine administration or CYP2D6 genotype caused a significant change in the mean concentrations of tamoxifen, B or X. In contrast, the mean steady state concentration of BX dropped from 1.65±0.88 ng/ml to 0.55±0.23 ng/ml after paroxetine treatment (p

Original languageEnglish (US)
JournalClinical Pharmacology and Therapeutics
Volume69
Issue number2
StatePublished - 2001
Externally publishedYes

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Hot Flashes
Cytochrome P-450 CYP2D6
Paroxetine
Tamoxifen
Genotype
Therapeutics
Patient Compliance
Fluorescence

ASJC Scopus subject areas

  • Pharmacology

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Coprescription of paroxetine with tamoxifen to reduce hot flashes reduced plasma 4-hydroxy-N-desmethyl-tamoxifen plasma concentrations in a CYP2D6-dependent manner. / Flockhart, D. A.; Hayes, D. F.; Rae, J. M.; Bhargava, P.; Morocho, A.; Stearns, V.

In: Clinical Pharmacology and Therapeutics, Vol. 69, No. 2, 2001.

Research output: Contribution to journalArticle

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AU - Hayes, D. F.

AU - Rae, J. M.

AU - Bhargava, P.

AU - Morocho, A.

AU - Stearns, V.

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