Hair analysis for pharmaceutical drugs. I. Effective extraction and determination of phenobarbital, phenytoin and their major metabolites in rat and human hair

Validated RP-LC Methods for Investigating the Degradation Behavior of Acefylline: Application for Analysis in Two Binary Mixtures

Background:

Acefylline (Acef) is a derivative of theophylline that has bronchodilator effects. Two binary mixtures were marketed for Acef: Acefylline piperazine/ Phenobarbitone (Acef-P/Phen) and Acefylline heptaminol/ Cinnarizine (Acef-H/ Cinn). To our knowledge none of the reported methods had the capacity to determine Acef in its binary mixture in presence of its degradation products and potential impurity theophylline (Theo).

Methods:

Two validated RP-LC methods were established for the determination of Acef-P/Phen and Acef-H/ Cinn in presence of Acef degradation products and its potential impurity Theo. A complete study of the forced acidic, alkaline and oxidative degradation of Acef was presented. The methods were based on LC separation on RP C18 columns using isocratic and gradient elution for Acef-P /Phen and Acef-H /Cinn mixtures, respectively. Different chromatographic conditions were examined and optimized.

Results:

Linear responses were attained over concentration ranges of 75-500/15-1000 μg/mL and 100-1000 /50- 500 μg/mL with mean percentage recoveries of (100.72±1.23)%/ (99.29±1.12)% and (100.44±1.27)%/ (99.01±0.97)% for Acef-P/Phen and Acef-H /Cinn, respectively. ICH guidelines were used for methods validation and all parameters were found to be acceptable.

Conclusion:

The methods showed to be accurate, precise and specific for the analysis of Acef-P/Phen and AcefH /Cinn in drug substance, drug product and in laboratory prepared mixtures in presence of Theo and up to 50% of degradation products. The structures of the main degradation products and the expected degradation pathway were suggested using the MS data.

Simultaneous determination of barbiturates, phenytoin and topiramate in hair by LC-MS/MS and application to real samples

INTRODUCTION

Hair analysis is useful for monitoring exposure to drugs such as antiepileptics owing to long-term therapy and a high possibility of abuse of drugs, which could be fatal. An effective and rapid analytical method for the simultaneous determination of six barbiturates, as well as phenytoin and topiramate in hair samples was developed and validated by liquid-chromatography-tandem mass spectrometry (LC-MS/MS).

METHODS

Three different extraction methods were investigated for the development of an appropriate analytical method. Hair was finely cut and then extracted with methanol, methanol containing 1% hydrochloric acid, and liquid-liquid extraction in acidic condition.

RESULTS

There was no significant difference in the matrix effects among these three methods. Recoveries clearly declined in the extraction involving both acidic methanol extraction and a LLE in acidic condition. Methanol incubation was chosen as the appropriate extraction method with acceptable matrix effects and recoveries. After validating the methanol incubation, the limit of detection (LOD) and limit of quantification (LOQ) were determined as 0.01 and 0.02 ng/mg for topiramate and 0.25-0.5 and 0.5-1 ng/mg for the others in hair. The LC-MS/MS method was precise and accurate with a dynamic linear range of 0.02-5 ng/mg for topiramate and 0.5 or 1-50 ng/mg for others. This method was applied to authentic hair samples of two drug users. The hair concentrations of phenobarbital were 0.2-17.1 ng/mg in segmental analysis in one female subject and those of topiramate were 0.19-0.93 ng/mg in another female subject.

DISCUSSION

The quantitative method was developed to determine 8 antiepileptics using LC-MS/MS. This method performed hair segmental analysis to provide useful informative and chronological data in both of the forensic and clinical toxicology fields.

Hair analysis in toxicological investigation of drug-facilitated crimes in Denmark over a 8-year period

Hair can serve as a specimen for identifying past drug exposure. Segmental hair analysis may differentiate a single exposure from chronic use. Consequently, segmental hair analysis is useful for disclosing a single drug ingestion, as well as for determining repeated exposures in drug-facilitated crimes (DFCs). This paper presents an overview of toxicological investigations that have used hair analysis in DFC cases from 2009 to 2016 in Denmark. Hair concentrations were determined for 24 DFC-related drugs and metabolites, including benzodiazepines and other hypnotics, antihistamines, opioid analgesics, antipsychotics, barbiturates, and illicit drugs from DFC cases. Drug detection in hair in DFC cases following a single or few intakes of chlorprothixene, codeine, diphenhydramine, oxazepam, oxycodone, promethazine, and phenobarbital is reported for the first time in forensic toxicology. A literature review on concentrations in the published DFC-related hair cases and on concentrations in hair of these substances after single and multiple doses is included. These cases demonstrate the value of segmental hair analysis in DFCs and facilitate future interpretations of results.

Analytical pitfalls in hair testing

This review focuses on possible pitfalls in hair testing procedures. Knowledge of such pitfalls is useful when developing and validating methods, since it can be used to avoid wrong results as well as wrong interpretations of correct results. In recent years, remarkable advances in sensitive and specific analytical techniques have enabled the analysis of drugs in alternative biological specimens such as hair. Modern analytical procedures for the determination of drugs in hair specimens - mainly by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) - are reviewed and critically discussed. Many tables containing information related to this topic are provided.

Surfactant enhanced liquid-phase microextraction of basic drugs of abuse in hair combined with high performance liquid chromatography

The aim of this study was to evaluate the performance of a technique for simultaneous testing of hydrophilic abuse drugs in hair. The analysis of, codeine and methadone in morphine hair included incubation in methanol (5h, 50 degrees C), Surfactant enhanced liquid-phase microextraction (SE-LPME) and HPLC analysis. This study has demonstrated that SE-LPME constitute a real alternative to the other liquid-phase microextraction methods, for pre-concentration and extraction of hydrophilic drugs in biological samples and has shown the advantages of these optimized methodologies over the traditional microextraction techniques. For these drugs recoveries in the range of 57.5-93.7 were obtained from hair. The drugs were enriched by a factor of 61-128 during SE-LPME. Linearity (r2, 0.9982-0.9997) was obtained in the range of 50-500 microg/l for morphine and 10-500 microg/l for codeine and methadone.

Determination of tramadol in hair using solid phase extraction and GC-MS

Tramadol is a centrally acting synthetic analgesic with mu-opioid receptor agonist activity, it is a widely prescribed analgesic used in the treatment of moderate to severe pain and as an alternative to opiates. Tramadol causes less respiratory depression than morphine at recommended doses. Its efficacy and low incidence of side effects lead to its unnecessary prescribing in patients with mild pain. Tramadol was classified as a "controlled drug" long after its approval for use in Jordan. Analysis of drugs of abuse in hair has been used in routine forensic toxicology as an alternative to blood in studying addiction history of drug abusers. A method for the determination of tramadol in hair using solid phase extraction and gas chromatography-mass spectrometry (GC-MS) is presented, the method offers excellent precision (3.5-9.8%, (M)=6.77%), accuracy (6.9-12%, M=9.4%) and limit of detection 0.5 ng/mg. The recovery was in the range of 87-94.3% with an average of 90.75%. The calibration curve was linear over the concentration range 0.5-5.0 ng/mg hair with correlation coefficient of 0.998. The developed method was tested on 11 hair samples taken from patients using tramadol as prescribed by their physician along with other different drugs in treating chronic illnesses. Tramadol was detected in all hair samples at a concentration of 0.176-16.3 ng/mg with mean concentration of 4.41 ng/mg. The developed method has the potential of being applied in forensic drug hair testing. In Jordan, hair drug testing started to draw the attention of legal authorities which stimulated forensic toxicologists in recent years to develop methods of analysis of drugs known or have the potential to be abused.

Hair analysis for pharmaceutical drugs. II. Effective extraction and determination of sildenafil (Viagra) and its N-desmethyl metabolite in rat and human hair by GC-MS

In order to study the incorporation of sildenafil (SDF) and its N-demethylated metabolite (norSDF) into hair, animal model experiments were carried out. After shaving the back hair, SDF was dosed to two sets of three male dark-agouti pigmented rats (5 weeks old) per each group at 25 mg/kg once a day for 5 successive days with intraperitoneal (i.p.) (set1) and oral administration (set2). The regrown back hair was collected 14 d after the first administration. Three typical extraction methods, using methanol-5 M hydrochloric acid, methanol-trifluoroacetic acid and 1 M sodium hydroxide, were evaluated using the rat hair samples containing SDF and norSDF. Methanol-5 M hydrochloric acid was the best extraction method in terms of high efficiency and reproducibility. The extract was purified using Bond Elut Certify columns and was derivatized with trimethylsilylimidazole: N,O-bis(trimethylsilyltrifluoroacetamide): trimethylchlorosilane (3: 3: 2) at 90 degrees C for 30 min. The trimethylsilylated products were analyzed by GC-MS using selected ion monitoring. SDF and norSDF were simultaneously detected in the rat hair. The hair concentrations were 4.9-6.3 (av. 5.8) ng/mg and 15.6-20.3 (av. 17.6) ng/mg for SDF and norSDF, respectively, with i.p. administration, and 2.6-4.1 (av. 3.6) ng/mg and 8.1-10.4 (av. 9.1) ng/mg with oral administration. The hair concentrations of norSDF were about three times higher than those of SDF, and the ratios of both compounds showed no significant difference between i.p. and oral administrations. This method was applied to the scalp hair of two patients who orally took SDF at regular intervals for the treatment of penile erectile dysfunction. The hair concentrations of SDF and norSDF in the two patients were 19.8 and 55.9 ng/mg, and 1.7 and 5.6 ng/mg, respectively.