Papers by Lolita Tsanaclis
British Journal of Clinical Pharmacology, Aug 1, 1985
The effect of anticonvulsant therapy on early morning concentration of cortisol in saliva and pla... more The effect of anticonvulsant therapy on early morning concentration of cortisol in saliva and plasma was assessed in a group of epileptic patients receiving regular phenytoin medication and the results compared with those obtained from a group of normal subjects not receiving drug therapy. 2 Values of cortisol in matched samples of plasma (331 + 23 nmol 1-1, mean + s.e. mean, n = 6) and saliva (11.4 + 0.9 nmol 1-1, mean + s.e. mean, n = 9) provided by epileptics did not differ significantly from those in the plasma (334 ± 41 nmol 1-1, mean ± s.e. mean) and saliva (12.0 + 2.0 nmol-1, mean + s.e. mean) of healthy volunteers (n = 12). 3 Six anticonvulsant-treated epileptics, together with six age and sex matched normal volunteers, each received intravenous dexamethasone (1 mg h-1) to determine the half-life of cortisol in plasma and saliva. In the anticonvulsant-treated group, the half-life of cortisol in plasma (73 + 5 min, mean + s.e. mean) and saliva (83 ± 5 min, mean ± s.e. mean) was reduced significantly (P < 0.01 plasma, P < 0.05 saliva) from that observed in healthy volunteers. In patients, the half life of cortisol and antipyrine showed a significant correlation (r2 = 0.75, P < 0.05 plasma, r2 = 0.71, P < 0.05 saliva). 4 The antipyrine half-life in saliva was reduced significantly (P < 0.02) and the antipyrine clearance rate, increased significantly (P < 0.005) in the treated epileptic group, reflecting drug-induced microsomal enzyme production. 5 The half-life of cortisol in plasma and saliva in subjects receiving anticonvulsant therapy probably depends on the degree of microsomal enzyme induction occurring in response to anticonvulsant therapy.
Aims: This work aimed to assess the performance of hair and fingernail ethyl glucuronide (EtG) me... more Aims: This work aimed to assess the performance of hair and fingernail ethyl glucuronide (EtG) measurement for use as a biomarker of alcohol consumption in persons with known drinking history across a range of drinking behaviours. Methods: EtG concentrations were assessed from the hair and fingernails of 50 study participants. Alcohol consumption of the previous 90 days was assessed by participant interview using the alcohol timeline follow-back method. EtG concentration was determined using LC-MS-MS using a method which was validated and accredited to ISO/IEC 17025 standards. Results: There was significant correlation between alcohol consumption and EtG concentrations found in hair and fingernail samples across the study group (n = 50). From participants testing positive for EtG (male n = 14, female n = 13) no significant difference was found between male and female EtG levels in either hair or fingernails. Across all participants there was no significant difference in hair or fingernail EtG concentration between male (n = 23) and females (n = 27). Conclusions: Our results support the use of EtG to indicate alcohol consumption over the previous 90 days, or~3 months as is the normal practice in hair analysis. The results confirm that fingernails can be a useful alternative matrix where hair samples are not available.
Revista paulista de medicina, 1981
Arquivos De Neuro-psiquiatria, Sep 1, 1981
Drug Testing and Analysis
Purpose: Ethyl glucuronide (EtG) is a biological marker in hair used to indicate abstinence or ex... more Purpose: Ethyl glucuronide (EtG) is a biological marker in hair used to indicate abstinence or excessive alcohol consumption. The main aim of this paper is to evaluate the stability of EtG in hair samples as it can potentially be affected by normal hygiene, and affect interpretation of the results. Methods: EtG was measured by GC-MS/MS in 102 hair samples, which were sectioned in three monthly sections when available to produce 291 sections of hair (sectioned set) and 468 hair samples (not sectioned set), where the most recent centimetre was analysed. Results :T he 95% percentiles of the EtG levels detected in the not sectioned set and in the first section of the sectioned set were 0.23 ng/mg (N = 468) and 0.22 ng/mg (N = 102), respectively. The 95% percentiles of the levels detected in the second sections and in the third sections were 0.15 ng/mg (N = 102) and 0.10 ng/mg (N = 87), respectively. Levels were below cut-off (0.01 ng/mg) in 61% in the not sectioned set and 67% in the se...
Short article / Article court Testing for alcohol use in hair: is ethyl glucuronide (EtG) stable ... more Short article / Article court Testing for alcohol use in hair: is ethyl glucuronide (EtG) stable in hair? Dépistage de la consommation d'alcool par l'analyse des cheveux : l'éthyl-glucuronide (EtG) est-il stable dans les cheveux ?
Stable isotope measurements have the potential to differentiate endogenous from exogenous gamma-h... more Stable isotope measurements have the potential to differentiate endogenous from exogenous gamma-hydroxybutyric acid (GHB) in biological matrices. We propose a clean-up method from urine using solid phase extraction (SPE) and analysis using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). We have determined δ13C (‰) values for three different reference standards of GHB (10 μg/ml sodium salt) derivatised with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) (#1 mean-30.6‰; σn-1 0.75; n=3: #2 mean-35.6‰; σn-1 0.52; n=3: #3 mean-42.9‰; σn-1 0.15; n=3). Urine samples (<1.62 μg/ml endogenous GHB) were ‘spiked ’ with 10 μg/ml of GHB standard, extracted from the matrix using SPE and derivatised with BSTFA, and the δ13C (‰) values (#1 mean-31.7‰; σn-1 0.15; n=3: #2 mean-34.0‰; σn-1 0.85; n=3: #3 mean-42.2‰; σn-1 0.64; n=3) compared with the standard preparation. Gamma-hydroxyvalerate (GHV) was used as an internal standard for quantitation purposes and as a contr...
Revista Intertox de Toxicologia, Risco Ambiental e Sociedade, 2015
Toxicologie Analytique et Clinique, 2014
Annales de Toxicologie Analytique, 2009
Short article / Article court Testing for alcohol use in hair: is ethyl glucuronide (EtG) stable ... more Short article / Article court Testing for alcohol use in hair: is ethyl glucuronide (EtG) stable in hair? Dépistage de la consommation d'alcool par l'analyse des cheveux : l'éthyl-glucuronide (EtG) est-il stable dans les cheveux ?
Therapeutic Drug Monitoring, 1996
The Syva Emit and Abbott TDx II kits for determination of methotrexate in serum were compared usi... more The Syva Emit and Abbott TDx II kits for determination of methotrexate in serum were compared using data from 14 samples distributed by the United Kingdom National External Quality Assessment Scheme to a mean of 38 European laboratories. For methotrexate concentrations above 0.2 mumol/L, there was no significant difference in the bias or coefficient of variation of measurements between the two techniques. A significantly greater number of measurements by Syva Emit (6.9%) were rejected as outliers &amp;amp;gt; 3 SD from the sample mean compared with Abbott TDx (1.3%). The lower sensitivity of the Syva Emit assay was evident in data reported for samples containing methotrexate concentrations below 0.2 mumol/L.
Therapeutic Drug Monitoring, 1997
The precision and accuracy of analytical methods currently in use for therapeutic drug monitoring... more The precision and accuracy of analytical methods currently in use for therapeutic drug monitoring were evaluated from proficiency test data provided by laboratories participating in the international Healthcontrol external quality assessment scheme for a range of eight antiepileptic drugs, theophylline, caffeine, and digoxin. Different analytical systems were assessed after grouping according to the reagent source and the analyzer used. The majority of analytical methods produced comparable levels of performance with coefficient of variation of &amp;amp;lt; 10% and accuracy within +/-7% of the spike value. Emit reagents were implemented successfully on diverse analyzers but data from the Cobas Mira were generally in the technique group with significantly lower precision. Bias problems were evident for a number of FPIA assays for specific drugs. For example, caffeine interference was present in theophylline measurements by Sigma FPIA reagents whereas use of nonhuman matrix caused a negative bias in Abbott FPIA measurements of carbamazepine. Measurements in the group with highest positive bias were produced by Roche FPIA reagents for phenytoin, phenobarbitone, and carbamazepine. Chromatographic and turbidimetric techniques performed satisfactorily. The variable performance of the different reagent/analyzer combinations demonstrates the value of the narrower technique classification in the assessment of assay performance.
Forensic Science International, 2008
Two groups were selected from the remainder of hair samples that had been tested for drugs at Tri... more Two groups were selected from the remainder of hair samples that had been tested for drugs at TrichoTech for medico-legal cases: samples that tested negative (drug-negative group; N=42, age 33.4+/-7.2 years) and samples that tested positive for drugs (drug-positive group; N=57, age 32.5+/-8.8 years). A rapid, simple method to detect the ethanol metabolite, ethyl glucuronide (EtG) in hair has been developed. The hair samples were sectioned, and then submitted to overnight sonication in water. Samples then underwent SPE using anion exchange cartridges, followed by derivatisation with N,O-bis[trimethylsilyl]trifluoroacetamide (BSTFA), before confirmation by GC-MS/MS. The assay produced excellent linearity and sensitivity over the calibration range 0.02-1.0 ng/mg, assuming a 10 mg hair sample. The mean age of the two groups was not statistically different (p=0.575, Student t-test), indicating a homogeneous group. Twelve of the 57 (21.0%) hair samples of the drug-positive group tested positive for EtG, and 17 of the 42 (40.5%) hair samples of the drug-negative group tested positive for EtG. The mean concentration of EtG in the drug-positive group was 0.011 ng/mg compared to 0.107 ng/mg in the drug-negative group. When the full results of this study were subjected to statistical analysis it was shown that EtG levels in the drug-negative group were statistically higher than those found in the drug-positive group (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05). This preliminary finding may be of use in the study of addiction and adds valuable data to previous studies regarding the use of EtG as a valuable marker for alcohol levels in hair.
British Journal of Clinical Pharmacology, 1986
The pharmacokinetics of antipyrine were examined after oral and intravenous administration to 20 ... more The pharmacokinetics of antipyrine were examined after oral and intravenous administration to 20 epileptic subjects receiving antiepileptic drug therapy. Bioavailability was essentially complete (mean bioavailability 101.2% + 14.4 (s.d.)) indicating that even in enzyme induced subjects, antipyrine behaves as a restrictively eliminated compound with negligible presystemic elimination in the gut or liver. Of the generally used measures of enzyme induction (oral clearance, oral half-life and intravenous half-life) oral clearance was the most closely related to the intravenous clearance of antipyrine (r = 0.919, P < 0.001). Oral antipyrine administration is an alternative to intravenous administration in epileptic subjects who are enzyme-induced.
Arquivos de Neuro-Psiquiatria, 1991
Quantitative measurements have indicated that heredity, cerebral damage, psycho-social aspects, i... more Quantitative measurements have indicated that heredity, cerebral damage, psycho-social aspects, ictal and inter-ictal phenomena and antiepileptic drugs may interfere in the cognitive dysfunction of epileptic patients. In the present study objective methods included immediate and late recall and recognition of pictures, Stroop test and auditory selection. Twenty patients with symptomatic localized epilepsy aged 17-52 years (27±10, mean ±sd) were compared to age and socially matched healthy controls. Patients were on therapeutic serum concentrations (25±12 m/mi) of phenobarbitone and had active epilepsy with 1.94 generalized tonic-clonic, 0.85 simple partial and 6.28 complex partial seizures monthly (means). Patients performed worse than controls in all 6 tests (p<0.05 to p<0.001), indicating a generalized cognitive deficit related to seizures and/or barbiturate therapy. We suggest further studies should be carried out in populations with uniform monotherapeutic regimens and epi...
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Papers by Lolita Tsanaclis