Periportal steatosis in mice affects distinct parameters of pericentral drug metabolism.

Little is known about the impact of morphological disorders in distinct zones on metabolic zonation. It was described recently that periportal fibrosis did affect the expression of CYP proteins, a set of pericentrally located drug-metabolizing enzymes. Here, we investigated whether periportal steatosis might have a similar effect. Periportal steatosis was induced in C57BL6/J mice by feeding a high-fat diet with low methionine/choline content for either two or four weeks. Steatosis severity was quantified using image analysis. Triglycerides and CYP activity were quantified in photometric or fluorometric assay. The distribution of CYP3A4, CYP1A2, CYP2D6, and CYP2E1 was visualized by immunohistochemistry. Pharmacokinetic parameters of test drugs were determined after injecting a drug cocktail (caffeine, codeine, and midazolam). The dietary model resulted in moderate to severe mixed steatosis confined to periportal and midzonal areas. Periportal steatosis did not affect the zonal distribution of CYP expression but the activity of selected CYPs was associated with steatosis severity. Caffeine elimination was accelerated by microvesicular steatosis, whereas midazolam elimination was delayed in macrovesicular steatosis. In summary, periportal steatosis affected parameters of pericentrally located drug metabolism. This observation calls for further investigations of the highly complex interrelationship between steatosis and drug metabolism and underlying signaling mechanisms.

Phosphatidylethanol, ethyl glucuronide and ethanol in blood as complementary biomarkers for alcohol consumption.

Alcohol biomarkers can monitor both recent and long-term drinking and provide information about drinking habits as a complement to self-reporting. Ethyl glucuronide (EtG) and phosphatidylethanol (PEth) are the most sensitive available biomarkers for this purpose. The present study aimed to collect data on both PEth and EtG in the same blood sample, in addition to ethanol, in order to evaluate the combined use of these biomarkers. Venous EDTA blood samples (n = 1149) sent to the laboratory as part of a clinical routine service for measuring PEth were investigated. PEth and EtG concentrations were analyzed using liquid chromatography-mass spectrometry methods and ethanol with an enzymatic method. Of the 1149 samples, 95 were positive for ethanol (range 0.11-3.12 g/L), 454 for EtG (1.0-9739 ng/mL), 635 for PEth (0.014-6.0 µmol/L), 534 for PEth ≥ 0.050 µmol/L, and 315 for PEth ≥ 0.30 µmol/L. EtG and PEth concentrations seemed largely independent as the coefficient of determination (r2) between PEth and EtG concentrations was 0.15. However, when the EtG concentrations were evaluated for different subgroups depending on ethanol or PEth concentrations a statistically significant difference between successive higher concentrations was observed. EtG and PEth are independent measures of recent alcohol drinking reflecting different time windows. Their combined measurement in the same blood sample is possible and will provide valuable information regarding recent alcohol consumption as a complement to self-reporting.

Ethyl glucuronide and ethanol concentrations in femoral blood, urine and vitreous humor from 117 autopsy cases.

BACKGROUND: Vitreous humor (VH) is a specimen of great value in forensic investigations and is being used for evaluating possible post-mortem formation of ethanol. Ethyl glucuronide (EtG) is an ethanol metabolite that has found interest for the same purpose. Both compounds can be measured in VH and because of differences in rate of distribution and elimination they may offer complementary information. METHODS: VH, femoral blood (FB) and urine were collected from 117 autopsy cases for forensic investigation. Ethanol was measured with headspace gas chromatography, while EtG was measured with liquid chromatography - tandem mass spectrometry. RESULTS AND CONCLUSION: Ethanol was detected in all matrices in 39 cases, while EtG was present in 62 cases. The VH-FB and the VH-urine ethanol concentrations in the 39 cases were statistically correlated (p < 0.00001). In one case with an ethanol concentration of 0.11 g/L in FB, no ethanol was detected in VH and urine, and no EtG in any specimen, indicating a possible post-mortem formation. EtG was present in VH in more cases than in FB and urine. The correlation between the EtG concentrations in VH and FB was statistically significant (p < 0.0003) as was the case also for VH and urine (p < 0.001). The combined information on ethanol and EtG concentrations in the three matrices can be used to interpret alcohol drinking habit before death. This study confirms the value of using VH as a specimen in forensic investigations regarding recent exposure to ethanol. EtG can be used not only for investigating post-mortem ethanol formation but also for estimating recent alcohol drinking.

Performance of PEth Compared With Other Alcohol Biomarkers in Subjects Presenting For Occupational and Pre-Employment Medical Examination.

AIMS: To compare the performance of short- and long-term alcohol biomarkers for the evaluation of alcohol drinking in employment-related health controls. METHODS: The 519 blood samples originated from 509 patients (80% men) presenting at occupational health units and medical centers at employment agencies for the evaluation of risky drinking. The laboratory investigation comprised the measurement of phosphatidylethanol (PEth 16:0/18:1), carbohydrate-deficient transferrin (CDT; % disialotransferrin), gamma-glutamyl transferase (GGT), mean corpuscular volume (MCV), ethanol and ethyl glucuronide (EtG). RESULTS: Many samples tested positive for acute (57%) and chronic (69%) alcohol biomarkers. PEth was the single most positive biomarker (64%; cut-off 0.05 µmol/l or 35 µg/l) and the only positive chronic biomarker in 100 cases. The highest PEth concentrations were seen in samples positive for all chronic biomarkers, followed by those also being CDT positive (cut-off 2.0%). All 126 CDT-positive samples were positive for PEth using the lower reporting limit (≥0.05 µmol/l) and for 114 cases (90%) also using the higher limit (≥0.30 µmol/l or 210 µg/l). In the CDT-positive cases, the PEth median concentration was 1.71 µmol/l, compared with 0.45 µmol/l for the CDT-negative cases (P < 0.0001). PEth and CDT values were correlated significantly (r = 0.63, P < 0.0001). Among the EtG-positive cases (≥1.0 ng/ml), 95% were also PEth positive, and all ethanol-positive cases (≥0.10 g/l) were also PEth positive. CONCLUSIONS: For optimal detection of drinking habits, using a combination of short- and long-term alcohol biomarkers provided best information. PEth was the single most positive alcohol biomarker, whereas GGT and MCV offered little additional value over PEth and CDT.

Potential of Oral Fluid as a Clinical Specimen for Compliance Monitoring of Psychopharmacotherapy.

BACKGROUND: Oral fluid (OF) is being developed as a specimen for the determination of drug intake as an alternative to serum and plasma. It is generally considered as an attractive specimen due to the noninvasive nature of the sampling procedure and the relation to the free fraction of drug in the blood. These features are of particular value in drug treatment of psychiatric disorders. To establish OF for the purpose of monitoring drug therapy, the relationship between concentrations in OF and serum/plasma must be documented. This study explored one promising sampling device and comprised the following 10 drugs: aripiprazole, citalopram, duloxetine, escitalopram, mirtazapine, pipamperone, pregabalin, promethazine, quetiapine, and venlafaxine. METHODS: For this purpose, 100 paired serum and OF samples were collected from patients undergoing pharmacotherapy and analyzed using a liquid chromatography-tandem mass spectrometry method. A commercial method from Chromsystems for the determination of these drugs in plasma was used and was adapted for OF and ultrafiltrated (Centrifree device) serum. RESULTS: The ratio of each individual pair of samples was used to calculate a mean and SD value between OF and serum free and total concentrations. The OF concentration ratios to serum total fraction differed markedly between substances and differed from 10-fold lower to 8-fold higher. The ratios to serum free fractions were always higher. The relation between the OF and serum concentrations was also evaluated by regression analysis and determination of slopes and correlation coefficients. For all measured relations, there was a statistically significant relation between the OF and serum concentrations. The degree of drug protein binding was in agreement with literature. The aripiprazole, duloxetine, pipamperone, pregabalin, and promethazine concentrations in ultrafiltrated serum were not possible to measure because of low concentrations and nonspecific binding. CONCLUSIONS: Despite a strong statistical correlation between OF and serum concentrations observed for most of the studied substances, it is still evident that OF concentrations cannot simply substitute serum/plasma as therapeutic drug monitoring specimen, but rather be considered as a unique specimen. We believe that OF is a promising matrix especially for compliance testing in psychiatry settings. The Greiner Bio-One device used in this study provides a sampling procedure that offers advantages over the available alternatives.