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Inhibition of CYP2D6 with low dose (5 mg) paroxetine in patients with high 10-hydroxynortriptyline serum levels-A prospective pharmacokinetic study

Jessurun, N. T., Vermeulen Windsant, A., Mikes, O., van Puijenbroek, E. P., van Marum, R. J., Grootens, K. & Derijks, H. J., 4-Jul-2020, In : British Journal of Clinical Pharmacology.

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  • Inhibition of CYP2D6 with low dose (5 mg) paroxetine in patients with high 10-hydroxynortriptyline serum levels-A prospective pharmacokinetic study

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DOI

The antidepressant nortriptyline is metabolized by cytochrome P450 2D6 (CYP2D6) to the less active and more cardiotoxic drug metabolite, 10-hydroxynortriptyline. High serum levels of this metabolite (>200 μg/L) may lead to withdrawal of nortriptyline therapy. Adding CYP2D6 inhibitors reduce the metabolic activity of CYP2D6 (phenoconversion) and so decrease the forming of hydroxynortriptyline. In this study, 5 mg paroxetine is administered to patients with high hydroxynortriptyline concentrations (>200 μg/L). The shift in number of patients to therapeutic nortriptyline (50-150 μg/L) and safe hydroxynortriptyline (<200 μg/L) concentrations, and the degree of phenoconversion, expressed as the change in ratio nortriptyline/hydroxynortriptyline concentrations before and after paroxetine addition, are prospectively observed and described. After paroxetine addition, 12 patients (80%) had therapeutic nortriptyline and safe hydroxynortriptyline concentrations. Hydroxynortriptyline concentrations decreased in all patients. The average nortriptyline/hydroxynortriptyline concentrations ratio increased from 0.32 to 0.59. This study shows that 5 mg paroxetine addition is able to lower high hydroxynortriptyline serum levels to safe ranges.

Original languageEnglish
JournalBritish Journal of Clinical Pharmacology
Publication statusE-pub ahead of print - 4-Jul-2020

    Keywords

  • NORTRIPTYLINE, ANTIDEPRESSANTS

ID: 130016799