Sensitive determination of Fluoxetine and Citalopram antidepressants in urine and wastewater samples by liquid chromatography coupled with photodiode array detector.

A new analyte separation and preconcentration method for the trace determination of antidepressant drugs, Fluoxetine (FLU) and Citalopram (CIT) in urine and wastewaters, was developed based on HPLC-DAD analysis after magnetic solid phase extraction (MSPE). In the proposed method, FLU and CIT were retained on the newly synthetized magnetic sorbent (Fe3O4@PPy-GO) in the presence of buffer (pH 10.0) and then were desorbed into a lower volume of acetonitrile prior to the chromatographic determinations. Before HPLC analysis, all samples were filtered through a 0.45 µm PTFE filter. Experimental parameters such as interaction time, desorption solvent and volume, and pH were studied and optimized in order to establish the detection limit, linearity, enrichment factor and other analytical figures of merit under optimum operation conditions. In the developed method, FLU and CIT were analyzed by diode array detector at the corresponding maximum wavelengths of 227 and 238 nm, respectively, by using an isocratic elution of 60% pH 3.0 buffer, 30% acetonitrile, and 10% methanol. By using the optimum conditions, limit of detections for FLU and CIT were 1.58 and 1.43 ng mL-1, respectively, while the limit of quantifications was 4.82 and 4.71 ng mL-1, respectively. Relative standard deviations (RSD%) for triplicate analyses of model solutions containing 100 ng mL-1 target molecules were found to be less than 5.0 %. Finally, the method was successfully applied to urine (both simulated and real healthy human) and wastewater samples, and quantitative results were obtained in recovery experiments.

Urinary selective serotonin reuptake inhibitors across critical windows of pregnancy establishment: a prospective cohort study of fecundability and pregnancy loss.

OBJECTIVE: To prospectively investigate the association of selective serotonin reuptake inhibitor (SSRI) exposure through critical windows of pregnancy establishment with fecundability and pregnancy loss. DESIGN: Prospective cohort study using longitudinal urine measurements of common SSRIs while women are actively trying to conceive. SETTING: Four clinical sites. PATIENT(S): A total of 1,228 women without uncontrolled depression/anxiety, attempting natural conception while participating in a randomized trial of preconception-initiated low-dose aspirin. INTERVENTIONS(S): Not applicable. MAIN OUTCOME MEASURE(S): Urinary SSRIs (fluoxetine, sertraline, escitalopram/citalopram) were measured while trying to conceive and, for women who became pregnant, at weeks 0, 4, and 8 of pregnancy. Fecundability odds ratios and incidence of pregnancy loss and live birth were estimated. RESULT(S): A total of 172 women (14%) were exposed to SSRIs while trying to conceive. SSRI exposure was associated with 24% reduced fecundability, and accordingly, a nonsignificant 9% lower live birth incidence, with significantly lower live birth in fluoxetine-exposed women. SSRI exposure was not associated with subsequent pregnancy loss, whether exposure was before conception or at 0, 4, or 8 weeks of gestation, although estimates varied by specific SSRI drug. CONCLUSION(S): Women using SSRIs may have more difficulty becoming pregnant, and although SSRI exposure overall was not associated with pregnancy loss, fluoxetine deserves caution and future study. CLINICAL TRIAL REGISTRATION NUMBER: NCT00467363.

Ultrasound-assisted dispersive liquid-liquid microextraction coupled with field-amplified capillary electrophoresis for sensitive and quantitative determination of fluoxetine and norfluoxetine enantiomers in biological fluids.

A rapid, simple, and sensitive technique for the quantitative detection of fluoxetine and norfluoxetine enantiomers in biological fluids was developed based on the combination of field-amplified sample stacking (FASS)-related capillary electrophoresis (CE) with ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME). The extraction efficiency of UA-DLLME was strongly related to extraction time, salt concentration, type of extraction and dispersion solvents, and volume of extraction and dispersion solvents. The extracted fluoxetine and norfluoxetine enantiomers in a mixture of 50% methanol and 50% deionized water were efficiently stacked using FASS and then separated using cyclodextrin-modified CE. Under optimal conditions of FASS (chiral selector, 3 mM trimethyl-ß-cyclodextrin; and background electrolyte, 100 mM phosphate buffer) and UA-DLLME (extraction solvent, 200 µL of acetone; and dispersed solvent, 50 µL of C2H2Cl4 in 1 mL of the sample solution), the obtained enrichment factors of fluoxetine and norfluoxetine enantiomers reached approximately 2000. The linear ranges for the quantification of fluoxetine and norfluoxetine enantiomers were 0.3-150 and 0.6-150 nM, respectively. The relative standard deviations in peak areas and migration time for four analytes were less than 3.3% and 6.3%, respectively. The proposed system provided limits of detection (signal-to-noise ratio of 3) for four analytes corresponding to 0.1 nM. The precision and accuracy for urine and serum samples were less than 6.8 and 8.3%, respectively. These findings suggested that the proposed system exhibited a high potential for the reliable determination of fluoxetine and norfluoxetine enantiomers in clinical samples. Graphical abstract.

A green and low-cost method employing switchable hydrophilicity solvent for the simultaneous determination of antidepressants in human urine by gas chromatography - mass spectrometry detection.

In this study, the use of switchable hydrophilicity solvent with a simple and low-cost lab-made device for the extraction procedure in homogeneous liquid-liquid microextraction is proposed for the first time in the determination of antidepressants in human urine. The antidepressants studied consisted of fluoxetine, amitriptyline, nortriptyline, imipramine, desipramine and sertraline. The optimization of the main parameters that can influence on the extraction efficiency was performed through multivariate approaches. The analytes were separated and identified by gas chromatography coupled to mass spectrometry (GC-MS). The optimal extraction conditions consisted of using N,N-dimethylcyclohexylamine (DMCHA) as the switchable hydrophilicity solvent (SHS), 500 µL of urine sample previously diluted with ultrapure water at 1:1 ratio (v/v), 200 µL of a mixture of SHS:HCl 6 mol L-1 (1:1 v/v), 600 µL of NaOH 10 mol L-1 and 3 min of extraction time. A volume of 40 µL of diphenylamine at concentration of 500 µg L-1 (20 ng) was used as internal standard. The method developed was in-house validated, providing coefficients of determination higher than 0.995 for all analytes, limits of detection (LOD) from 0.02 to 0.88 µg L-1, limits of quantification (LOQ) from 0.05 to 2.92 µg L-1, relative recoveries of 68 to 102%, intra-day precision from 0.5 to 15.9%, inter-day precision from 4.2 to 19.3%, selectivity and robustness. The method proposed was successfully applied in five human urine samples from a Toxicological Information Center located in Porto Alegre (Brazil). The results demonstrated that the µP-SHS-HLLME approach is highly cost-effective, rapid, simple and environmentally-friendly with satisfactory analytical performance.

Magnetic solid-phase extraction coupled with UHPLC-MS/MS for four antidepressants and one metabolite in clinical plasma and urine samples.

Aim: Routine therapeutic drug monitoring is highly recommended since common antidepressant combinations increase the risk of drug-drug interactions or overlapping toxicity. Materials & methods: A magnetic solid-phase extraction by using C18-functionalized magnetic silica nanoparticles (C18-Fe3O4@SiO2 NPs) as sorbent was proposed for rapid extraction of venlafaxine, paroxetine, fluoxetine, norfluoxetine and sertraline from clinical plasma and urine samples followed by ultra-HPLC-MS/MS assay. Results: The synthesized C18-Fe3O4@SiO2 NPs showed high magnetization and efficient extraction for the analytes. After cleanup by magnetic solid-phase extraction, no matrix effects were found in plasma and urine matrices. The analytes showed LODs among 0.15-0.75 ng ml-1, appropriate linearity (R ≥ 0.9990) from 2.5 to 1000 ng ml-1, acceptable accuracies 89.1-110.9% with precisions ≤11.0%. The protocol was successfully applied for the analysis of patients' plasma and urine samples. Conclusion: It shows high potential in routine therapeutic drug monitoring of clinical biological samples.

Storage of urine specimens in point of care (POC) urine drug testing cups reduces concentrations of many drugs.

BACKGROUND: Many clinical toxicology laboratories receive urine specimens in urine cups that contain point of care (POC) drug testing strips. We conducted this study to evaluate the effect on the stability of commonly measured drugs in the clinical toxicology laboratory when urine is exposed to POC urine drug testing cups. METHODS: Drug free urine was spiked with 85 drugs that were measured by a validated liquid chromatography mass spectrometry (LCMS) method after exposure to POC urine drug testing cups at ambient and 2-6 °C temperatures. Alterations ≥20% were defined as significant changes in the drugs concentration. RESULTS: Concentrations of amitriptyline, cyclobenzaprine, fentanyl, fluoxetine, flunitrazepam, nortriptyline, paroxetine, and sertraline were significantly reduced when urine specimens were stored inside POC urine drug testing cups for 24 h at ambient temperature. Storage of urine in urine chemistry dipsticks reduced the concentration of several drugs. When spiked urine was exposed to an increasing number of POC urine drug testing strips, the concentrations of some drugs were reduced in a dose-dependent manner. The drugs that were absorbed by POC urine drug testing strips were partially back extracted from the strips. CONCLUSION: Exposure of urine specimens to POC urine drug testing strips reduces the concentration of several drugs measured by LCMS method.

Improved Analytical Approach Based on QuECHERS/UHPLC-PDA for Quantification of Fluoxetine, Clomipramine and their Active Metabolites in Human Urine Samples.

This paper reports, for the first time, the development of a modified Quick, Easy, Cheap Effective, Rugged and Safe (QuEChERS) combined with a dispersive SPE (d-SPE) based clean-up procedure as a new and powerful strategy for the simultaneous and efficient isolation of two different antidepressants, fluoxetine and clomipramine, and their active metabolites in human urine samples. A univariate experimental design with four independent variables such as sample volume, extraction solvent, buffered salts and clean-up step, was performed and used to investigate the effect of process variables on the extraction efficiency. Good linearity was achieved at the studied concentration range (0.1-5.0 µg mL-1), with correlation coefficients (R2) higher than 0.9961. Low detection limits, ranging between 0.060 and 0.092 µg mL-1 were obtained for all analytes, whereas the lowest quantification limit was 0.1 µg mL-1, corresponding to the lowest concentration of the standard curve. The method also showed good results for accuracy, with values ranging from 91% to 105%. Intra- and inter-day precision, expressed as the relative standard deviation (RSD), were also satisfactory (<10%). Consistent recoveries of antidepressants ranging from 86% to 109% were observed when urine samples were fortified at three concentrations, namely 0.1, 2.5 and 5.0 µg mL-1 In order to evaluate the proposed method for clinical use, the QuEChERS/UHPLC-PDA method was applied to analysis of 12 urine samples from depressed patients.

Optimization of alcohol-assisted dispersive liquid-liquid microextraction by experimental design for the rapid determination of fluoxetine in biological samples.

A sensitive and rapid method based on alcohol-assisted dispersive liquid-liquid microextraction followed by high-performance liquid chromatography for the determination of fluoxetine in human plasma and urine samples was developed. The effects of six parameters on the extraction recovery were investigated and optimized utilizing Plackett-Burman design and Box-Benken design, respectively. According to the Plackett-Burman design results, the volume of disperser solvent, extraction time, and stirring speed had no effect on the recovery of fluoxetine. The optimized conditions included a mixture of 172 µL of 1-octanol as extraction solvent and 400 µL of methanol as disperser solvent, pH of 11.3 and 0% w/v of salt in the sample solution. Replicating the experiment in optimized condition for five times, gave the average extraction recoveries equal to 90.15%. The detection limit of fluoxetine in human plasma was obtained 3 ng/mL, and the linearity was in the range of 10-1200 ng/mL. The corresponding values for human urine were 4.2 ng/mL with the linearity range from 10 to 2000 ng/mL. Relative standard deviations for intra and inter day extraction of fluoxetine were less than 7% in five measurements. The developed method was successfully applied for the determination of fluoxetine in human plasma and urine samples.

Determination of fluoxetine in pharmaceutical and biological samples based on the silver nanoparticle enhanced fluorescence of fluoxetine-terbium complex.

In this study, a simple and sensitive spectrofluorimetric method is presented for the determination of fluoxetine based on the enhancing effect of silver nanoparticles (AgNPs) on the terbium-fluoxetine fluorescence emission. The AgNPs were prepared by a simple reduction method and characterized by UV-Vis spectroscopy and transmission electron microscopy. It was indicated that these AgNPs have a remarkable amplifying effect on the terbium-sensitized fluorescence of fluoxetine. The effects of various parameters such as AgNP and Tb3+ concentration and the pH of the media were investigated. Under obtained optimal conditions, the fluorescence intensity of the terbium-fluoxetine-AgNP system was enhanced linearly by increasing the concentration of fluoxetine in the range of 0.008 to 19 mg/L. The limit of detection (b + 3s) was 8.3 × 10-4 mg/L. The interference effects of common species found in real samples were also studied. The method had good linearity, recovery, reproducibility and sensitivity, and was satisfactorily applied for the determination of fluoxetine in tablet formulations, human urine and plasma samples. Copyright © 2016 John Wiley & Sons, Ltd.

An improved analytical strategy combining microextraction by packed sorbent combined with ultra high pressure liquid chromatography for the determination of fluoxetine, clomipramine and their active metabolites in human urine.

A powerful and sensitive method, by microextraction packed sorbent (MEPS), and ultra-high performance liquid chromatography (UHPLC) with a photodiode array (PDA) detection, is described for the determination of fluoxetine, clomipramine and their active metabolites in human urine samples. The MEPS variables, such as sample volume, pH, number of extraction cycles (draw-eject), and desorption conditions (solvent and solvent volume of elution) were optimized. The analysis were carried out using small sample volumes (500µL) and in a short time period (5min for the entire sample preparation step). Good linearity was obtained for all antidepressants with the correlation coefficients (R(2)) above 0.9965. The limits of detection (LOD) ranged from 0.068 to 0.087µgmL(-1). The recoveries were from 93% to 98%, with relative standard deviations less than 6%. The inter-day precision, expressed as the relative standard deviation, varied between 3.8% and 8.5% while the intra-day precision between 3.0% and 7.1%. In order to evaluate the proposed method for clinical use, the MEPS/UHPLC-PDA method was applied to analysis of urine samples from depressed patients.

Repetitive injection field-amplified sample stacking for cationic compounds determination.

The development of a field-amplified sample stacking technique is presented. Sensitivity enhancement in this technique was obtained by repetitive injections of a sample followed by steps of sample matrix removal through the application of counter-pressure. Under optimized conditions the background electrolyte (BGE) was composed of 80 mM H3PO4 while the sample matrix contained 0.5mM H3PO4 and 30% (v/v) methanol. The elaborated method enabled a 4-fold effective injection of the sample (53 s, 0.5 psi). Each injection was followed by a focusing step during which the application of a voltage (2 kV) and counter-pressure (-1 psi) was performed for 0.65 min. The method was developed for the determination of six psychiatric drugs (opipramol, hydroxyzine, promazine, amitriptyline, fluoxetine, and thioridazine). The elaborated method was applied for analysis of human urine samples after a simple liquid-liquid extraction procedure. The detection limits obtained were in the range of 2.23-6.21 ng/mL.

Arrays of SnO2 nanorods as novel solid phase microextraction for trace analysis of antidepressant drugs in body fluids.

The arrays of tin oxide nanorods-solid phase microextraction (ATN-SPME) fibre coupled with the high performance liquid chromatography (HPLC) method was developed for simultaneous determination of selective serotonin reuptake inhibitors (SSRI), citalopram and fluoxetine, in human urine and plasma samples. The variables of interest in the Direct-SPME (D-SPME) were extraction time, pH, ion strength or salt percentage and desorption time of analytes from the fibre. These factors were optimised by using a Box-Behnken design and the response surface equations were developed. The optimal experimental conditions obtained from this statistical evaluation included: the salt percentage (30%, w/v), NaOH volume (6.5 µl from a 1 M solution), extraction time (10 min) and desorption time (30 min) for drugs in the plasma sample and The salt percentage (30%, w/v), NaOH volume (100 µl from a 1 M solution), extraction time (18 min) and desorption time (23 min) for drugs in the urine sample. A satisfactory reproducibility for the extraction from urine and plasma samples (R.S.D.<10%) was obtained. The linearity for urine and plasma ranged from 1 to 5×10(5) ng ml(-1) with a detection limit of 0.2 ng ml(-1) for citalopram and 0.5 ng ml(-1) for fluoxetine, which covered the typical urinary concentrations obtained for citalopram and fluoxetine.

Extraction of fluoxetine from aquatic and urine samples using sodium dodecyl sulfate-coated iron oxide magnetic nanoparticles followed by spectrofluorimetric determination.

A new method based on the combination of magnetic solid phase extraction (MSPE) and spectrofluorimetric determination was developed for isolation and preconcentration of fluoxetine form aquatic and biological samples using sodium dodecyl sulfate (SDS) coated Fe(3)O(4) nanoparticles (NPs) as a sorbent. The unique properties of Fe(3)O(4) NPs including high surface area and strong magnetism were utilized effectively in the MSPE process. Effect of different parameters influencing the extraction efficiency of fluoxetine including the amount of Fe(3)O(4) and SDS, pH value, sample volume, extraction time, desorption solvent and time were optimized. Under optimized condition, the method was successfully applied to the extraction of fluoxetine from water and urine samples and absolute recovery amount of 85%, detection limit of 20 µg L(-1) and a relative standard deviation (RSD) of 1.4% were obtained. The method linear response was over a range of 50-1000 µg L(-1) with R(2)=0.9968. The relative recovery in different aquatic and urine matrices were investigated and values of 80% to 104% were obtained. The whole procedure showed to be conveniently fast, efficient and economical for extraction of fluoxetine from environmental and biological samples.

Gas chromatography-mass spectrometry detection of a norfluoxetine artifact in hydrolyzed urine samples may falsely indicate tranylcypromine ingestion.

In several cases, fluoxetine, its metabolites, its known artifacts, and supposedly tranylcypromine were detected in urine using the authors' systematic toxicological analysis (STA) procedure based on acid hydrolysis, extraction, and acetylation. As fluoxetine and tranylcypromine are absolutely contraindicated drugs and in none of the cases was tranylcypromine prescribed, the question of whether the detected compound might have been formed by fluoxetine and/or its metabolites arose. Therefore, rat urine taken after dosing with fluoxetine was screened in the same way. In addition, aqueous solutions of fluoxetine, norfluoxetine, tranylcypromine, and a mixture of the latter two drugs were worked-up and analyzed according to the STA and without hydrolysis. In urine specimens obtained from rats dosed with fluoxetine, tranylcypromine was detected as well as in the solution of worked-up norfluoxetine including hydrolysis. Its underlying mass spectrum could be identified by detailed interpretation of the fragmentation patterns as acetylated 3-phenyl-propyl-2-ene-amine. This compound could be postulated as hydrolysis product of norfluoxetine formed by ether cleavage and water elimination. Although this spectrum shows nearly the same fragmentation patterns as that of acetylated tranylcypromine, both compounds could finally be differentiated by their retention indices and by using the positive-ion chemical ionization mode.

Rapid quantitative analysis of letrozole, fluoxetine and their metabolites in biological and environmental samples by MEKC.

A micellar electrokinetic chromatographic method has been developed to analyze biological (human serum, saliva and urine) and environmental samples (three different water samples) for letrozole (LE), fluoxetine and their main metabolites. For this purpose a 20 mM borate buffer (pH 9.5) containing 20 mM SDS and 12% v:v 2-propanol was used as the background electrolyte. The samples were hydrodynamically injected for 6 s, separated in a fused-silica capillary at 25 kV and 50 degrees C and detected at 230 nm. Under these conditions, the migration times for all the studied compounds ranged from 3.0 up to 8.0 min. Linearity ranges were determined as 125-1500 ng/mL, whereas detection limits were from 37 to 120 ng/mL in biological samples and a value of 6 ng/mL in water samples. According to the validation study, the developed method was proved to be accurate, precise, sensitive, specific, rugged and robust. This method was applied to the analysis of different biological fluids at clinical levels, including two urine samples from patients undergoing treatment with LE or fluoxetine, and also to environmental samples at potentially polluting level. Prior to the determination, the samples were purified and pre-concentrated by means of an extraction-preconcentration step with a C18 cartridge and by eluting the compounds with methanol.

Rapid HPLC method for the simultaneous monitoring of duloxetine, venlaflaxine, fluoxetine and paroxetine in biofluids.

A simple and rapid HPLC method is developed for the determination of two serotonin-norepinephrine-reuptake inhibitors (duloxetine and venlaflaxine) and two selective serotonin-reuptake inhibitors (fluoxetine and paroxetine) in human biofluids. Separation was performed on an Inertsil ODS-3 column (250 x 4.0 mm, 5 µm) with acetonitrile-ammonium acetate (0.05 M, 41:59 v/v) at 235 nm, within 7 min. SPE on Oasis(®) HLB cartridges was applied for the isolation of analytes from biofluids. The developed methodology was validated in terms of sensitivity, linearity, accuracy, precision, stability and selectivity. Relative standard deviation was less than 10.4%. Limit of detection was 0.2-0.6 ng/µl in blood plasma and 0.1-0.8 ng/µl in urine. The method was successfully applied to biofluids from a patient under duloxetine treatment.

[Chemico-toxicological study of fluoxetine].

Selected aspects of chemico-toxicological analysis of the tranquillizer drug fluoxetine are described. Optimal conditions for fluoxetin extraction from internal organs and biological fluids (blood, urine) are specified and methods proposed for its detection and quantitation including TLC, UV SPM, and HPLC. The proposed methods were verified using laboratory animals and materials for expert examination.

Quality assessment of fluoxetine and fluvoxamine pharmaceutical formulations purchased in different countries or via the Internet by 19F and 2D DOSY 1H NMR.

A simple and selective (19)F NMR method has been validated for the quantitation of fluoxetine (FLX) and fluvoxamine (FLV) in methanol solutions and in human plasma and urine. The regression equations for FLX and FLV showed a good linearity in the range of 1.4-620 microg mL(-1) (3.3 x 10(-6)-1.8 x 10(-3) mol L(-1)) with a limit of detection of approximately 0.5 microg mL(-1) (1.3 x 10(-6) mol L(-1)) and a limit of quantification of approximately 2 microg mL(-1) (4.6 x 10(-6) mol L(-1)). The precision of the assay depends on the concentrations and is comprised between 1.5 and 9.5% for a range of concentrations between 1.2 x 10(-3) and 3.2 x 10(-6) mol L(-1). The accuracy evaluated through recovery studies ranged from approximately 96 to 103% in methanol solutions and in urine, and from approximately 93 to 104% in plasma, with standard deviations <7.5%. The low sensitivity of the method precludes its use for the assay of these antidepressants in biofluids at least at therapeutic doses as the ranges of FLX and FLV plasma levels are 0.15-0.5 microg mL(-1) and 0.15-0.25 microg mL(-1), respectively. The method was applied successfully to the determination of FLX and FLV contents in pharmaceutical samples (brand-named and generic) purchased in several countries or via the Internet. All the commercial formulations contain the active ingredient in the range 94-103% of stated concentration. A "signature" of the formulations (solid and liquid) was obtained with 2D Diffusion-Ordered SpectroscopY (DOSY) (1)H NMR which allowed the characterisation of the active ingredient and excipients present in the formulations studied. Finally, the DOSY separation of FLX and FLV whose molecular weights are very close was obtained by using beta-cyclodextrin as host-guest complexing agent.

Simultaneous determination of citalopram, fluoxetine and their main metabolites in human urine samples by solid-phase microextraction coupled with high-performance liquid chromatography.

A liquid chromatography method was developed for the determination of some frequently prescribed selective serotonin re-uptake inhibitors (SSRI) - citalopram and fluoxetine - and its main metabolites - demethylcitalopram, didemethylcitalopram and norfluoxetine - in human urine samples, using a previous stage of solid-phase microextraction. All the extraction parameters influencing adsorption (extraction time, temperature, pH, ion strength and organic modifier addition) and desorption (desorption time and desorption solvent mixture composition) of the analytes on the fiber have been studied. A satisfactory reproducibility for extraction from urine samples (R.S.D.<10%) was obtained. The linearity for urine ranged from 0.05 to 2 mg l(-1) with limits of detection close to 0.01 mg l(-1), which cover the typical urinary concentrations obtained for citalopram, fluoxetine and their metabolites.

The distribution of fluoxetine in human fluids and tissues.

Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) that was introduced in 1986. Certain side effects of this medication-drowsiness, dizziness, abnormal vision, diarrhea, and headache-could affect pilot performance and become a factor in an aviation accident. Our laboratory has determined the distribution of fluoxetine and its desmethyl metabolite, norfluoxetine, in various postmortem tissues and fluids from 10 fatal aviation accident cases. When available, 11 specimen types were analyzed for each case, including blood, urine, vitreous humor, bile, liver, kidney, skeletal muscle, lung, spleen, heart muscle, and brain. Blood fluoxetine concentrations in these 10 cases ranged from 21 to 1480 ng/mL. The distribution coefficients for both fluoxetine and norfluoxetine, expressed as specimen/blood ratios, were determined. The distribution coefficients for fluoxetine were determined to be 0.9 +/- 0.4 for urine, 0.10 +/- 0.03 for vitreous humor, 9 +/- 1 for bile, 38 +/- 10 for liver, 60 +/- 17 for lung, 9 +/- 3 for kidney, 20 +/- 5 for spleen, 2.2 +/- 0.3 for muscle, 15 +/- 3 for brain, and 10 +/- 2 for heart. To our knowledge, this is the first report presenting the distribution of fluoxetine in humans at therapeutic concentrations.