Hair as a Specimen to Document Tetramethylene Disulfotetramine Exposure
ABSTRACT Tetramethylene disulfotetramine (tetramine) is a rodenticide that has been banned for many years in China. Since 2005, inhabitants of a village in the Henan Province have been suffering from grand mal seizures. To investigate the possibility of tetramine as the cause, we developed a method to determine tetramine in human hair. Sample preparation involved external decontamination, frozen pulverization, and ultrasonication in 2 mL ethyl acetate in the presence of cocaine-d3 as an internal standard. The method exhibited good linearity; calibration curve was linear over a range of 0.1-20 ng/mg hair. The limit of detection for the assay was 0.05 ng/mg hair. Except for one subject (No. 4), all head and pubic hair samples were positive for tetramine. The concentrations of tetramine in pubic hair were significantly higher than those in the same subjects' head hair samples. Because of a long retention in body, segmental head hair analysis cannot provide an accurate exposure history of tetramine in the body.
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ABSTRACT: Bromadiolone and brodifacoum, two common anticoagulant rodenticides, are involved in the majority of anticoagulant rodenticide poisoning cases in humans in China. Hair analysis can provide long-term information on drug exposure. A method using liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) was developed and validated for the measurement of bromadiolone and brodifacoum in human hair. A 1 mL aliquot of a phosphate buffer solution (pH 6.8) was added to 20 mg of pulverized hair followed by ultrasonication and liquid-liquid extraction. Liquid chromatography was performed using a C(18) column with a mobile phase gradient of ammonium acetate (10 mM) and methanol. A tandem mass spectrometer in multiple reaction monitoring mode with a negative electrospray ionization source was employed for detection. Warfarin-d(5) was used as an internal standard for both analytes. The limits of detection (LODs) for bromadiolone and brodifacoum were 0.010 and 0.025 ng/mg, respectively. The calibration curves for both analytes were linear from 0.025 to 1 ng/mg. The accuracy ranged from 90.3 to 109.3%, and the intra-day and inter-day imprecisions were less than 15%. The established method was found effective when applied to the analyses of bromadiolone or brodifacoum in five cases, indicating that segmental hair analysis could be useful for clinical and forensic purposes by identifying the time of ingestion. Copyright © 2013 John Wiley & Sons, Ltd.Rapid Communications in Mass Spectrometry 02/2013; 27(4):513-20. DOI:10.1002/rcm.6477
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ABSTRACT: Pre-exposure prophylaxis (PrEP) trials using tenofovir-based regimens have demonstrated that high levels of adherence are required to evaluate efficacy; the incorporation of objective biomarkers of adherence in trial design has been essential to interpretation, given the inaccuracy of self-report. Antiretroviral measurements in scalp hair have been useful as a marker of long-term exposure in the HIV treatment setting, and hair samples are relatively easy and inexpensive to collect, transport, and store for analysis. To evaluate the relationship between dose and tenofovir concentrations in hair, we examined the dose proportionality of tenofovir in hair in healthy, HIV-uninfected adults. A phase I, crossover pharmacokinetic study was performed in 24 HIV-negative adults receiving directly-observed oral tenofovir tablets administered 2, 4, and 7 doses/week for 6 weeks, with a ≥3-week break between periods. Small samples of hair were collected after each six-week period and analyzed for tenofovir concentrations. Geometric-mean-ratios compared levels between each pair of dosing conditions. Intensive plasma pharmacokinetic studies were performed during the daily-dosing period to calculate areas-under-the-time-concentration curves (AUCs). Over 90% of doses were observed per protocol. Median tenofovir concentrations in hair increased monotonically with dose. A log-linear relationship was seen between dose and hair levels, with an estimated 76% (95% CI 60-93%) increase in hair level per 2-fold dose increase. Tenofovir plasma AUCs modestly predicted drug concentrations in hair. This study found a strong linear relationship between frequency of dosing and tenofovir levels in scalp hair. The analysis of quantitative drug levels in hair has the potential to improve adherence measurement in the PrEP field and may be helpful in determining exposure thresholds for protection and explaining failures in PrEP trials. Hair measures for adherence monitoring may also facilitate adherence measurement in real-world settings and merit further investigation in upcoming PrEP implementation studies and programs. ClinicalTrials.gov +NCT00903084.PLoS ONE 01/2014; 9(1):e83736. DOI:10.1371/journal.pone.0083736