The concentration of three anti-seizure medications in hair: the effects of hair color, controlling for dose and age

Earwax as an alternative specimen for forensic analysis

In this work, we presented, for the first time, earwax as an alternative forensic specimen for detecting 12 neuropsychotic drugs employing liquid chromatography-tandem mass spectrometry in positive and negative ion modes after straightforward extraction with methanol. The method was validated and standard curves were established by external calibration with correlation coefficients >0.99. All precision, accuracy, matrix effects, extraction recoveries, and carryover were within acceptable limits; limits of quantification were sufficiently low to quantify almost all the samples tested. To confirm the feasibility of the study, earwax specimens were collected from actual patients treated with different combinations of the 12 drugs and analyzed by our method; the 12 drugs could be quantified from the earwax specimens of the users successfully, showing usefulness of earwax specimens, because of its noninvasive sampling and the storage of drug(s) for relatively long time together with its being relatively less contaminated by environmental impurities. This study is pioneering; many detailed studies on earwax as an alternative specimen remain to be explored.

Non-invasive biomonitoring for PFRs and PBDEs: new insights in analysis of human hair externally exposed to selected flame retardants

In this study, we investigated the hypothesis whether externally adsorbed and internally deposited flame retardants (FRs) in hair could be distinguished. To this extent, hair samples collected from one volunteer were exposed under controlled conditions to phosphate FR (PFR) and polybrominated diphenyl ether (PBDE) standards to mimic external contamination. Afterwards, suitable washing procedures to selectively remove contaminants from the hair surface were investigated. The samples were measured by GC-(ECNI)-MS for PBDEs and LC-(ESI+)-MS/MS for PFRs. All investigated compounds were transferred onto the hair surface. One of the most important finding was that dust particles are not mandatory to transfer compounds on the hair surface and to be able to measure high levels of compounds in human hair. To assess different protocols to selectively remove external contamination, the exposed hair samples were washed in different media before analysis: water, methanol, hexane:dichloromethane (1:1, v/v), acetone and shampoo. Results indicated that there is no washing medium able to entirely and exclusively remove external contamination. Among investigated media, methanol removed a meaningful part of the external contamination (42-105%), but the removal efficiencies differed among compounds. We therefore concluded that hair should not be washed prior to analysis and in case of visible contamination (e.g. with cosmetic products), water would be the recommended agent. Organic solvents should not be used for the washing step. Although it is impossible to distinguish external from internal exposure, hair samples may be used as valuable biomarker of human exposure, providing a measure of integral exposure. To the best of our knowledge, this is the first study which has used externally exposed hair samples to PBDEs and PFRs.

Therapeutic drug monitoring of antiepileptic drugs by use of saliva

Blood (serum/plasma) antiepileptic drug (AED) therapeutic drug monitoring (TDM) has proven to be an invaluable surrogate marker for individualizing and optimizing the drug management of patients with epilepsy. Since 1989, there has been an exponential increase in AEDs with 23 currently licensed for clinical use, and recently, there has been renewed and extensive interest in the use of saliva as an alternative matrix for AED TDM. The advantages of saliva include the fact that for many AEDs it reflects the free (pharmacologically active) concentration in serum; it is readily sampled, can be sampled repetitively, and sampling is noninvasive; does not require the expertise of a phlebotomist; and is preferred by many patients, particularly children and the elderly. For each AED, this review summarizes the key pharmacokinetic characteristics relevant to the practice of TDM, discusses the use of other biological matrices with particular emphasis on saliva and the evidence that saliva concentration reflects those in serum. Also discussed are the indications for salivary AED TDM, the key factors to consider when saliva sampling is to be undertaken, and finally, a practical protocol is described so as to enable AED TDM to be applied optimally and effectively in the clinical setting. Overall, there is compelling evidence that salivary TDM can be usefully applied so as to optimize the treatment of epilepsy with carbamazepine, clobazam, ethosuximide, gabapentin, lacosamide, lamotrigine, levetiracetam, oxcarbazepine, phenobarbital, phenytoin, primidone, topiramate, and zonisamide. Salivary TDM of valproic acid is probably not helpful, whereas for clonazepam, eslicarbazepine acetate, felbamate, pregabalin, retigabine, rufinamide, stiripentol, tiagabine, and vigabatrin, the data are sparse or nonexistent.