Clinlab Navigator

Fluoxetine

Fluoxetine is a selective serotonin reuptake inhibitor approved for treatment of bulimia, obsessive-compulsive behavior, panic, premenstrual dysphoria, and major depressive disorder. Both fluoxetine and its major metabolite, norfluoxetine, are pharmacologically active. Due to the long half-lives of parent and metabolite (1-6 days), it may take several weeks for patients to reach steady-state concentrations. Significant interindividual variability in fluoxetine pharmacokinetics has been reported. Fluoxetine is a potent inhibitor of CYP2D6 and is subject to numerous drug interactions.

The most common side effects of fluoxetine therapy include nausea, nervousness, anxiety, insomnia, and drowsiness. Anticholinergic and cardiovascular side effects are markedly reduced compared to tricyclic antidepressants. Fatalities from fluoxetine overdose are extremely rare.

Therapeutic drug monitoring is useful when patients are taking other medications that may be inhibitory, dose or formulation changes, and assessment of compliance Since both fluoxetine and its metabolite are pharmacologically active, both concentrations should be measured. Fluoxetine and norfluoxetine are measured by liquid chomatography/tandem mass spectrometry. Most individuals respond optimally when combined serum concentrations for both parent and metabolite are in the therapeutic range of 120-300 ng/mL. A toxic range has not been well established.

Specimen requirement is a red top tube of blood.

References

Wille SM, Cooreman SG, Neels, HM, Lambert WE: Relevant issues in the monitoring and toxicology of antidepressants. Crit Rev Clin Lab Sci 2008;45(1):25-89

Baumann P, Hiemke C, Ulrich S, et al: The AGNP-TDM expert group consensus guidelines: therapeutic drug monitoring in psychiatry. Pharmacopsychiatry 2004;37:243-265

Updated Articles

Protein Urine…

Urine protein is a mixture of plasma proteins, renal tubular proteins and those from the lower urinary tract. Very little plasma protein crosses the glomerular capillary membranes in healthy individuals. Traces of albumin and beta globulins may be…

New Articles

Arsenic

Arsenic is a natural component of the earth’s crust and is widely distributed throughout the environment. Arsenic exists in trivalent and pentavalent forms, as well as methylated compounds, monomethylarsonic acid and dimethylarsenic acid. All of…

Blog

USPSTF 2018…

In 2012, the United States Preventive Services Task Force (USPSTF) recommended against screening for prostate cancer with prostate specific antigen (PSA). This year, USPSTF published an update on PSA based screening for prostate cancer. Their review…