An Insight into Gabapentin and Pregabalin in Scottish Prisoners.

The aim of this study was to evaluate the prevalence and abuse potential of antiepileptic drugs (AEDs) among prison populations in Scotland, UK. Participants consisted of all admitted and released prisoners over a 1 month period who consented to provide samples. Urine samples were collected and analyzed by liquid chromatography coupled with triple quadrupole tandem mass spectrometry using a method validated for the simultaneous quantification of 21 AEDs in urine. A total of 904 samples were collected. The samples were also screened for drugs of abuse by using point-of-care testing kits. A total of 18% of the samples were positive for AEDs. Gabapentin (GBP) was identified in 118 samples (13%) and pregabalin (PRG) in 32 samples (3.5%). Interestingly, 12 samples contained both drugs (1.3%). The concentrations ranged from 0.5 to 1,100 mg/L (median, 15 mg/L) for GBP and from 0.5 to 440 mg/L (median, 7.3 mg/L) for PRG. Four samples were found to have concentrations >400 mg/L, two samples for GBP and two samples for PRG. These concentrations are at least 20 times above the median concentrations. Other AEDs detected were levetiracetam (four samples), vigabatrin (four samples), lamotrigine (three samples), valproic acid (three samples), carbamazepine (two samples) and topiramate (one sample). Illicit or non-prescribed drugs were detected in 81% of urine samples of which 80% were from admitted prisoners and 20% from released prisoners. Benzodiazepines, opiates and cannabis were the most frequently detected drugs. Other drugs found in positive AED samples were methadone (26%), cocaine (18%), buprenorphine (17%), amphetamines (4%), methamphetamines (4%) and barbiturates (4%). This study shows a high prevalence of AEDs within the Scottish prison system, primarily due to GBP and PRG; however, due to the anonymity of the sample collection, it is unknown if these are prescribed or illicit drug ingestions.

Simultaneous analysis of 22 antiepileptic drugs in postmortem blood, serum and plasma using LC-MS-MS with a focus on their role in forensic cases.

In recent years, there has been a growth in reports of antiepileptic drugs (AEDs) being misused on their own or in combination with other drugs of abuse in a variety of toxicological case types such as drug abuse, suicide, overdose and drug facilitated crime. To our knowledge, there are no simultaneous quantification methods for the analysis of the most commonly encountered AEDs in postmortem whole blood and clinical plasma/serum samples at the same time. A simple, accurate and cost-effective liquid chromatography-tandem mass spectrometric (LC-MS-MS) method has been developed and validated for the simultaneous quantification of carbamazepine (CBZ) and its metabolite CBZ-10,11-epoxide, eslicarbazepine acetate, oxcarbazepine and S-licarbazepine as a metabolite, gabapentin, lacosamide, lamotrigine, levetiracetam, pregabalin, phenobarbital, phenytoin and its metabolite 5-(p-hydroxyphenyl)-5-phenylhydantoin, retigabine (ezogabine) and its metabolite N-acetyl retigabine, rufinamide, stiripentol, topiramate, tiagabine, valproic acid, vigabatrin and zonisamide in postmortem whole blood, serum and plasma which would be suitable for routine forensic toxicological analysis and therapeutic drug monitoring. All AEDs were detected and quantified within 17 min without endogenous interferences. The correlation coefficient (R(2)) was >0.995 for all AEDs with accuracy ranging from 90 to 113% and precision <13% for all analytes. The recovery ranged from 70 to 98%. No carryover was observed in a blank control injected after the highest standard and the matrix effect was acceptable and ranged from 90 to 120%. The method has been successfully verified using authentic case samples that had previously been quantified using different methods.