Inpharma 1362 - 2 Nov 2002

Olanzapine + fluvoxamine:pharmacokinetic interactions

Fluvoxamine increases serum concentrations ofolanzapine and clinical response in patients withschizophrenia, report researchers from Germany andIsrael.

Their study involved 8 patients with chronicschizophrenia who had been receiving olanzapine10–20 mg/day for ≥ 3 months, with no change inolanzapine dosage from ≥ 8 weeks before the study tothe end of the study. During the study, the patientsreceived additional fluvoxamine 100 mg/day for 8weeks.

By the end of the study, serum concentrations ofolanzapine had increased from baseline by a mean of54.9% (range 12%–112%). Interestingly, serumconcentrations of the metabolite N-desmethylolanzapine, which were measured in 5patients, were constantly increased in 3 and decreasedin 2 patients during fluvoxamine administration.Unexpectedly, fluvoxamine concentrations did notreach steady state during the 8 weeks of administration,suggesting that olanzapine may affect the metabolism offluvoxamine.

Of 7 evaluable patients, 5 had a > 20% improvementfrom baseline in their score on the Schedule for theAssessment of Negative Symptoms. ‘Although thecombination was well tolerated and associated withclinical improvement, combined olanzapine andfluvoxamine should be used cautiously and controlledclinically and by therapeutic drug monitoring to avoidolanzapine-induced side effects or intoxication’,comment the researchers.Hiemke C, et al. Fluvoxamine augmentation of olanzapine in chronicschizophrenia: pharmacokinetic interactions and clinical effects. Journal of ClinicalPsychopharmacology 22: 502-506, Oct 2002 800920489

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Inpharma 2 Nov 2002 No. 13621173-8324/10/1362-0001/$14.95 Adis © 2010 Springer International Publishing AG. All rights reserved