Evaluation of urinary cyclohexanediols and cyclohexanol as biomarkers of occupational exposure to cyclohexane.

OBJECTIVES: The aim of the present study was to comparatively evaluate the usefulness of urinary cyclohexanediols (CHdiols-U) and cyclohexanol (CHol-U) as biomarkers of occupational exposure to cyclohexane (CH). METHODS: Sixteen subjects (14 men and 2 women) were exposed to CH during proof-printing work. Personal exposure monitoring was conducted during the whole shift on the last working day of the week. The time-weighted average level of exposure to CH (CH-A) was measured using a diffusive sampler. Two urine samples were collected from each worker at different times during the same week: a baseline urine sample (before the first shift of the working week, after a 5-day holiday with no CH exposure) and an end-of-shift urine sample (after the last shift of the same working week, the same day personal exposure monitoring was conducted). CH-A, CHdiols-U and CHol-U were determined using a gas chromatograph-flame ionization detector. RESULTS: The CH-A concentrations ranged from 4.5 to 60.3 ppm, with a geometric mean (GM) of 18.1 ppm. The GMs and ranges (in parenthesis) of the creatinine (cr)-corrected end-of-shift 1,2-CHdiol-U, 1,4-CHdiol-U and CHol-U concentrations were 12.1 (4.1-36.6), 7.5 (2.4-20.1) and 0.4 (0.2-1.0) mg/g cr, respectively. Both CHdiols-U at the end of the shift were significantly correlated with CH-A (correlation coefficients for 1,2-CHdiol-U and 1,4-CHdiol-U of 0.852 and 0.847, respectively). No correlation was observed between CH-A and CHol-U. CONCLUSIONS: CHdiols-U at the end of the last shift of the working week are suitable biomarkers of occupational exposure to CH, but CHol-U is not suitable.

Coupling of solid phase microextraction with electrospray ionization ion mobility spectrometry and direct analysis of venlafaxine in human urine and plasma.

The capability of electrospray ionization-conventional ion mobility spectrometry (ESI-IMS) for direct analysis of the samples extracted by solid phase microextraction (SPME) was investigated and evaluated for the first time. To that end, an appropriate new desorption chamber was designed and constructed, resulting in the possibility of direct exposure of the SPME fiber to the electrospray solvent flow. Two different elution methods in dynamic and static modes were exhaustively investigated. The results indicated that the interface could help us to have an accurate and sensitive analysis without disturbing the electrospray process, in static elution method. Venlafaxine as a test compound was extracted from human urine and plasma by a convenient headspace SPME method. The positive ion mobility spectrum of the extracted drug was obtained and the analyte responses were calculated. The coupled method of SPME-ESI-IMS was comprehensively validated in terms of sensitivity, dynamic range, and recovery percentage. Finally, various real samples of human urine and plasma were analyzed, all verifying the feasibility and success of the proposed method for the easy routine analysis.

Mechanisms for eliminating monoterpenes of sagebrush by specialist and generalist rabbits.

Pygmy rabbits (Brachylagus idahoensis) are one of only three vertebrates that subsist virtually exclusively on sagebrush (Artemisia spp.), which contains high levels of monoterpenes that can be toxic. We examined the mechanisms used by specialist pygmy rabbits to eliminate 1,8-cineole, a monoterpene of sagebrush, and compared them with those of cottontail rabbits (Sylvilagus nuttalli), a generalist herbivore. Rabbits were offered food pellets with increasing concentrations of cineole, and we measured voluntary intake and excretion of cineole metabolites in feces and urine. We expected pygmy rabbits to consume more, but excrete cineole more rapidly by using less-energetically expensive methods of detoxification than cottontails. Pygmy rabbits consumed 3-5 times more cineole than cottontails relative to their metabolic body mass, and excreted up to 2 times more cineole metabolites in their urine than did cottontails. Urinary metabolites excreted by pygmy rabbits were 20 % more highly-oxidized and 6 times less-conjugated than those of cottontails. Twenty percent of all cineole metabolites recovered from pygmy rabbits were in feces, whereas cottontails did not excrete fecal metabolites. When compared to other mammals that consume cineole, pygmy rabbits voluntarily consumed more, and excreted more cineole metabolites in feces, but they excreted less oxidized and more conjugated cineole metabolites in urine. Pygmy rabbits seem to have a greater capacity to minimize systemic exposure to cineole than do cottontails, and other cineole-consumers, by minimizing absorption and maximizing detoxification of ingested cineole. However, mechanisms that lower systemic exposure to cineole may come with a higher energetic cost in pygmy rabbits than in other mammalian herbivores.

A method for CP 47, 497 a synthetic non-traditional cannabinoid in human urine using liquid chromatography tandem mass spectrometry.

A rapid method has been developed to analyse CP 47, 497 in human urine. Urine samples were diluted with water:acetonitrile (90:10, v/v) and sample aliquots were analysed by triple quadrupole tandem mass spectrometry with a runtime of 5 min. Multiple reaction monitoring (MRM) as survey scan was performed. The method was validated in urine, according to an in-house validation protocol based on the criteria defined in Commission Decision 2002/657/EC. Three MRM transitions were monitored. The decision limit (CCα) was 0.01µg mL⁻¹ and for the detection capability a (CCß) value of 0.02 µg mL⁻¹ was obtained. The measurement uncertainty of the method was 21%. Fortifying human urine samples (n=18) in three separate assays, show the accuracy of the method to be between 95 and 96%. The precision of the method, expressed as RSD values for the within-lab reproducibility at the three levels of fortification (0.1, 0.15 and 0.2 µg mL⁻¹) was less than 10% respectively. The method proved to be simple, robust and time efficient. To the best of our knowledge there are no LC-MS methods for the determination of CP 47, 497 with validation data in urine.

Quantification of 1,8-cineole and of its metabolites in humans using stable isotope dilution assays.

The metabolism of 1,8-cineole after ingestion of sage tea was studied. After application of the tea, the metabolites 2-hydroxy-1,8-cineole, 3-hydroxy-1,8-cineole, 9-hydroxy-1,8-cineole and, for the first time in humans, 7-hydroxy-1,8-cineole were identified in plasma and urine of one volunteer. For quantitation of these metabolites and the parent compound, stable isotope dilution assays were developed after synthesis of [(2)H(3)]-1,8-cineole, [9/10-(2)H(3)]-2-hydroxy-1,8-cineole and [(13)C,(2)H(2)]-9-hydroxy-1,8-cineole as internal standards. Using these standards, we quantified 1,8-cineole by solid phase microextraction GC-MS and the hydroxyl-1,8-cineoles by LC-MS/MS after deconjugation in blood and urine of the volunteer. After consumption of 1.02 mg 1,8-cineole (19 µg/kg bw), the hydroxycineoles along with their parent compound were detectable in the blood plasma of the volunteer under study after liberation from their glucuronides with 2-hydroxycineole being the predominant metabolite at a maximum plasma concentration of 86 nmol/L followed by the 9-hydroxy isomer at a maximum plasma concentration of 33 nmol/L. The parent compound 1,8-cineole showed a low maximum plasma concentration of 19 nmol/L. In urine, 2-hydroxycineole also showed highest contents followed by its 9-isomer. Summing up the urinary excretion over 10 h, 2-hydroxycineole, the 9-isomer, the 3-isomer and the 7-isomer accounted for 20.9, 17.2, 10.6 and 3.8% of the cineole dose, respectively.

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.

Interference by venlafaxine ingestion in the detection of tramadol by liquid chromatography linked to tandem mass spectrometry for the screening of illicit drugs in human urine.

Confirmation of the presence of illicit drugs in human fluids by liquid chromatography linked to atmospheric pressure ionisation tandem mass spectrometry (LC/MS/MS) is becoming increasingly popular. A rapid LC/MS/MS method is described using reversed phase gradient elution chromatography on a 50 x 3 mm base deactivated C8 column with identification of drugs based on their Multiple Reaction monitoring (MRM) transitions, retention time, and co-elution of stable isotopic analogues where available. The method is used for drug confirmation following initial screening by immunoassay, and identification of drugs such as tramadol, for which no immunoassay is available. False positive results for tramadol were observed in cases where subjects were being treated with the commonly prescribed antidepressant drug venlafaxine. This was a result of the presence of the metabolite O-desmethylvenlafaxine, which has a similar transition to tramadol. This study highlights the need to consider drug metabolites, as well as parent drugs in interferences in LC/MS/MS methods.

Rapid screening of selective serotonin re-uptake inhibitors in urine samples using solid-phase microextraction gas chromatography-mass spectrometry.

In this paper a solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) method is proposed for a rapid analysis of some frequently prescribed selective serotonin re-uptake inhibitors (SSRI)-venlafaxine, fluvoxamine, mirtazapine, fluoxetine, citalopram, and sertraline-in urine samples. The SPME-based method enables simultaneous determination of the target SSRI after simple in-situ derivatization of some of the target compounds. Calibration curves in water and in urine were validated and statistically compared. This revealed the absence of matrix effect and, in consequence, the possibility of quantifying SSRI in urine samples by external water calibration. Intra-day and inter-day precision was satisfactory for all the target compounds (relative standard deviation, RSD, <14%) and the detection limits achieved were <0.4 ng mL(-1) urine. The time required for the SPME step and for GC analysis (30 min each) enables high throughput. The method was applied to real urine samples from different patients being treated with some of these pharmaceuticals. Some SSRI metabolites were also detected and tentatively identified.

Constraint of feeding by chronic ingestion of 1,8-cineole in the brushtail possum (Trichosurus vulpecula).

Eucalyptus leaf-eating marsupials such as the brushtail possum (Trichosurus vulpecula) ingest large amounts of terpenes, especially 1,8-cineole (cineole)--the major component of many eucalyptus oils. Brushtail possums were acclimated to a non-Eucalyptus diet with increasing concentrations of cineole (0.5-4.0% wet weight) added over 18 d. We measured food and cineole consumption and urinary metabolites of cineole. Food intake decreased with cineole content, indicating that it was constrained by the maximum tolerable intake of cineole that was 3.8 +/- 0.2 g kg(-1) or 5.2 +/- 0.3 g kg(-0.75) (mean +/- SE, N = 6). The pattern of metabolites was similar at all cineole intakes (56% hydroxycineolic acids, 27% cineolic acids, 13% hydroxycineoles, and 4% dihydroxycineoles). In another experiment, possums maintained on artificial diet were abruptly presented with 4% cineole for 5 d. Food intake fell by 45 +/- 6% (mean +/- SE, N = 6) and mean cineole intake was 2.9 +/- 0.3 g kg(-1). There was evidence of induction of secondary oxidative pathways, as hydroxycineoles were the major metabolites (48% total) on the first day, but rapidly dropped to 15% on subsequent days as the acid metabolites increased. These findings indicate that ingestion of cineole is not constrained by selective saturation of individual enzymes involved in its multiple pathways of oxidation, but rather the total detoxification capacity appears to limit feeding on a cineole diet.

Effects of two plant secondary metabolites, cineole and gallic acid, on nightly feeding patterns of the common brushtail possum.

We investigated effects of two plant secondary metabolites (PSMs), cineole and gallic acid, on the nightly feeding behavior of the common brushtail possum (Trichosurus vulpecula), a generalist folivore. We tested whether possums altered their feeding behavior in response to increasing levels of cineole, a dietary terpene. Possums were fed artificial diets containing three levels of cineole: zero (basal diet), medium (6.8% of total dry matter, DM), and high (15.3% DM). In another experiment, we introduced gallic acid, a dietary phenolic, into the diets. Possums were offered a Choice PSM diet (cineole and gallic acid diets simultaneously) or a No-Choice PSM diet (containing either cineole or gallic acid). Detoxification products of cineole and gallic acid were examined in urine to determine that different detoxification pathways were utilized in the elimination of each compound. With increasing cineole levels, possums ate less, had smaller feeding bouts, and had a lower rate of intake, but did not extend their total nightly feeding time. Possums offered the Choice PSM diet, compared with the No-Choice diets, ate more, had larger feeding bouts, and tended to increase their rate of intake. Results from the urinary analysis indicated that gallic acid and cineole were not involved in competing detoxification pathways in brushtail possums. There was also a significant sex effect: females ate more overall, ate more per feeding bout, and ate at a higher rate than males. These results indicate that PSMs not only constrain overall intake, but that possums alter their feeding behavior in response to them. Altered feeding patterns may reduce the negative influence of PSMs on intake.

Massive venlafaxine overdose resulted in a false positive Abbott AxSYM urine immunoassay for phencyclidine.

CASE REPORT: A 13-yr-old girl overdosed on 48 x 150 mg venlafaxine (Effexor XR). She was taking venlafaxine regularly for depression. Her only other medications included topical Benzamycin and pyridoxine 50 mg daily for acne. The Abbott AxSYM assay was positive only for phencyclidine, but GC/MS did not confirm the presence of phencyclidine. Toxilab identified only one substance, confirmed by GC/MS as venlafaxine. A serum sample obtained 3 h after her ingestion revealed a venlafaxine concentration of 24460 ng/mL and an O-desmethylvenlafaxine concentration of 3930 ng/mL, confirming the massive acute overdose (therapeutic range of venlafaxine and O-desmethylvenlafaxine together is 250-750 ng/mL). Urine spiked with 4.2 mg/mL ofvenlafaxine and 0.7 mg/mL of O-desmethylvenlafaxine was interpreted as positive with the Abbott AxSYM fluorescent polarized immunoassay for phencyclidine (readout of 28 ng/mL). CONCLUSION: Venlafaxine may cause a false positive Abbott AxSYM phencyclidine assay when present in very high concentrations. Physicians should be aware of this potential reaction when interpreting urine drug immunoassays.

Effect of ethanol on the urinary excretion of cyclohexanol and cyclohexanediols, biomarkers of the exposure to cyclohexanone, cyclohexane and cyclohexanol in humans.

OBJECTIVES: This study explored the acute effect of ethanol (EtOH) on the urinary excretion of cyclohexanol (CH-ol), 1,2- and 1,4-cyclohexanediol (CH-diol), biomarkers of exposure to important solvents, and chemical intermediates cyclohexanone (CH-one), cyclohexane (CH) and cyclohexanol. METHODS: Volunteers (5-8 in each group) were exposed for 8 hours either to CH-one, CH or CH-ol vapor at concentrations of about 200, 1000, and 200 mg/m3, respectively, with concomitant ingestion of EtOH (4 14-g doses taken during the exposure). Urine was collected for 72 hours and analyzed for CH-ol and CH-diols using a procedure involving acidic hydrolysis and gas chromatographic determination. RESULTS: The metabolic yields of CH-ol, 1,2-, and 1,4-CH-diol, respectively, in the exposures with EtOH were as follows: 11.3%, 36%, 23% after the exposure to CH-one, 3.1%, 15%, 8% after the exposure to CH, and 6.6%, 24%, 18% after the exposure to CH-ol. [The corresponding values obtained previously in matching experiments without EtOH were as follows: 1.0%, 39%, 18% (CH-one); 0.5%, 23%, 11% (CH); and 1.1%, 19%, 8% (CH-ol).] The excretion curves of the metabolites in the exposures with EtOH were not delayed when compared with the corresponding curves of a comparison group. CONCLUSIONS: The urinary excretion of CH-diols is much less sensitive to EtOH than that of CH-ol. It is recommended to employ CH-diols as useful and more reliable biomarkers of exposure to CH-one, CH and CH-ol in field examinations.

Biological monitoring of occupational exposure to cyclohexane by urinary 1,2- and 1,4-cyclohexanediol determination.

OBJECTIVES: This article reports the results obtained with the biological and environmental monitoring of occupational exposure to cyclohexane using 1,2-cyclohexanediol (1,2-DIOL) and 1,4-DIOL in urine. The kinetic profile of 1,2-DIOL in urine suggested by a physiologically based pharmacokinetic (PBPK) model was compared with the results obtained in workers. METHODS: Individual exposure to cyclohexane was measured in 156 workers employed in shoe and leather factories. The biological monitoring of cyclohexane exposure was done by measurement of 1,2-DIOL and 1,4-DIOL in urine collected on different days of the working week. In all, 29 workers provided urine samples on Monday (before and after the work shift) and 47 workers provided biological samples on Thursday at the end of the shift and on Friday morning. Another 86 workers provided biological samples at the end of the work shift only on Monday or Thursday. RESULTS: Individual exposure to cyclohexane ranged from 7 to 617 mg/ m3 (geometric mean value 60 mg/m3). Urinary concentrations of 1,2-DIOL (geometric mean) were 3.1, 7.6, 13.2, and 6.3 mg/g creatinine on Monday (pre- and postshift), Thursday (postshift) and Friday (pre-shift), respectively. The corresponding values recorded for 1,4-DIOL were 2.8, 5.1, 7.8, and 3.7 mg/g creatinine. A fairly close, statistically significant correlation was found between environmental exposure to cyclohexane and postshift urinary 1,2-DIOL and 1,4-DIOL on Monday. Data collected on Thursday and Friday showed only a poor correlation to exposure with a wide scatter. Both metabolites have a urinary half-life of close to 18 h and accumulate during the working week. CONCLUSIONS: Comparison between data obtained from a PBPK model and those found in workers suggests that 1,2-DIOL and 1,4-DIOL are urinary metabolites suitable for the biological monitoring of industrial exposure to cyclohexane.

1,2- and 1,4-Cyclohexanediol: major urinary metabolites and biomarkers of exposure to cyclohexane, cyclohexanone, and cyclohexanol in humans.

The metabolism and toxicokinetics of cyclohexane (CH) and cyclohexanol (CH-ol), important solvents and chemical intermediates, were studied in volunteers after 8-h periods of inhalation exposure at concentrations of 1010 and 236 mg m(-3), respectively (occupational exposure limits: CH, 1050 mg m(-3); CH-ol, 200 mg m(-3)). Of the dose of absorbed parent compounds, the yields of urinary CH-ol and 1,2- and 1,4-cyclohexanediol (CH-diol) were 0.5%, 23.4%, and 11.3%, respectively, after exposure to CH and 1.1%, 19.1%, and 8.4%, respectively, after exposure to CH-ol as determined by a gas chromatography method involving hydrolysis of glucuronide conjugates. The metabolic patterns of CH and CH-ol were very similar to that of cyclohexanone (CH-one) studied in the laboratory previously. For all three compounds, peak excretion of CH-ol occurred at the end of the exposure period, after which it decayed rapidly. Excretion curves of 1,2- and 1,4-CH-diol reached maximal values within 0-6 h postexposure, with subsequent elimination half-lives being 14-18 h. The rate-limiting step in the elimination of CH compounds from the organism is renal clearance of CH-diols. Determination of CH-diols in end-of-shift urine samples is recommended as a useful new method of biomonitoring of CH, CH-ol, and CH-one at the workplace. However, due to accumulation of CH-diols in the body during repeated exposure, quantitative relationships between the exposure and the level of CH-diols have to be adjusted according to the day of sampling during the working week.

Distribution of venlafaxine in three postmortem cases.

Venlafaxine (V) is a second-generation antidepressant approved for use in the United States in 1993. It is a derivative of phenethylamine and is structurally unrelated to first- and other second-generation antidepressants. Nevertheless, its mechanism of action is similar to other antidepressants; it inhibits the reuptake of presynaptic norepinephrine and serotonin. Its major routes of elimination involve O and N demethylation. O-Desmethylvenlafaxine (ODV) is biologically active. Therapeutic concentrations of V and ODV are approximately 0.2 and 0.4 mg/L, respectively. Three cases of drug intoxication involving V are presented. V and ODV were identified by gas chromatography-nitrogen-phosphorus detection after alkaline extraction of the biological specimen. On an HP-5 column, V and ODV elute after bupropion and fluoxetine, but prior to the first-generation antidepressants, sertraline, amoxapine, and trazodone. V and ODV were confirmed by full scan electron impact gas chromatography-mass spectrometry. The heart-blood V and ODV concentrations (mg/L) in the three cases were 6.6 and 31; 84 and 15; and 44 and 50, respectively. In Case 1, acetaminophen and diphenhydramine were found in the heart blood at 140 and 2.6 mg/L respectively. In Case 2, amitriptyline, nortriptyline, and chlordiazepoxide were found in the blood at 2.8, 0.5 and 3.3 mg/L, respectively. In each case, the manner of death was suicide.

Investigation on neurotoxicity of occupational exposure to cyclohexane: a neurophysiological study.

OBJECTIVES: To examine the effect of occupational exposure to cyclohexane on the peripheral nervous system. METHODS: A nerve conduction study was performed on 18 workers exposed to cyclohexane in a luggage factory and on age and sex matched occupationally unexposed controls. 12 workers had been exposed to n-hexane (median 2.8 years) before the start of exposure to cyclohexane. To confirm the effect of exposure, a follow up study was performed on nine workers one year after the first study. The mean exposure to cyclohexane was 1.2 years in the first study. A symptom survey was performed. The exposure was measured by air sampling of the breathing zone of each worker. The urinary metabolite cyclohexanol was also monitored. RESULTS: The concentration of airborne cyclohexane ranged from 5 to 211 ppm. The urinary concentration of cyclohexanol ranged from 0.12 to 1.51 mg/l. There was a strong correlation between the cyclohexane exposure in personal air and urinary cyclohexanol. No differences were found in nerve conduction velocities (NCV) between workers exposed to cyclohexane and age and sex matched controls. The results of the follow up study showed significant improvements in peroneal motor NCV (P < 0.01) and sural sensory NCV (P < 0.05) and in ulnar motor distal latency (MDL, P < 0.05) and peroneal MDL (P < 0.05) compared with the first study. Although the past n-hexane exposure affected the first neurophysiological study, the effect had disappeared in the second study, one year later. CONCLUSION: Occupational exposure to the concentrations of cyclohexane experienced in this study had no adverse effects on the peripheral nervous system.

A high-performance liquid chromatographic method for the simultaneous determination of venlafaxine and O-desmethylvenlafaxine in biological fluids.

A rapid, accurate, and sensitive high-performance liquid chromatographic (HPLC) method for simultaneous determination of venlafaxine (V) and O-desmethylvenlafaxine (ODV) in plasma and urine has been developed. V and ODV are extracted from plasma using a liquid-liquid extraction procedure, chromatographed on a Supelcosil LC-8DB column, and quantitated by UV detection at 229 nm. Linearity was established over the range 10-500 ng/ml for V and 7.2-720 ng/ml for ODV using 1.0 ml of human, rat, dog, and mouse plasma. For urine, for both analytes, an analytical range 0.1-10.0 micrograms/ml was established. Accuracy of > +/- 10% about the theoretical mean was achieved for all matrices, with intra- and interday coefficients of variation for precision of < 10%. Endogenous components in plasma and/or urine or known metabolites of V do not interfere in the determination of the analytes. For both V and ODV a quantitation limit of 10 ng/ml for plasma was adequate for their estimation over a period of three half-lives, following administration of a pharmacologic dose in man, and the limit of 0.1 microgram/ml, for urine, can monitor excretion of as little as 0.5% of the dose.

Metabolic disposition of 14C-venlafaxine in mouse, rat, dog, rhesus monkey and man.

1. The metabolic disposition of venlafaxine has been studied in mouse, rat, dog, rhesus monkey and man after oral doses (22, 22, 2, and 10 mg/kg, and 50 mg, respectively) of 14C-venlafaxine as the hydrochloride. 2. In all species, over 85% of the administered radioactivity was recovered in the urine within 72 h, indicating extensive absorption from the GI tract and renal excretion. 3. Venlafaxine was extensively metabolized, with only 13.0, 1.8, 7.9, 0.3 and 4.7% dose appearing as parent compound in urine of mouse, rat, dog, monkey and man, respectively. The metabolite profile varied significantly among species, but primary metabolic reactions were demethylations and the conjugation of phase I metabolites. Hydroxylation of the cyclohexyl ring also occurred in mouse, rat and monkey, and a cyclic product was formed in rat and monkey. Glucuronidation was the primary conjugation reaction, although sulphate conjugates were also detected in mouse urine. 4. While no metabolite constituted more than 20% dose in any species except man, the major urinary metabolites were: mouse, N,O-didesmethyl-venlafaxine glucuronide; rat, cis-1,4-dihydroxy-venlafaxine; dog, O-desmethyl-venlafaxine glucuronide; monkey, N,N,O-tridesmethyl-venlafaxine; and man, O-desmethyl-venlafaxine.