Covalent protein adduction by drugs of abuse

Recreational abuse of the drugs cocaine, methamphetamine, and morphine continues to be prevalent in the United States of America and around the world. While numerous methods of detection exist for each drug, they are generally limited by the lifetime of the parent drug and its metabolites in the body. However, the covalent modification of endogenous proteins by these drugs of abuse may act as biomarkers of exposure and allow for extension of detection windows for these drugs beyond the lifetime of parent molecules or metabolites in the free fraction. Additionally, existence of covalently bound molecules arising from drug ingestion can offer insight into downstream toxicities associated with each of these drugs. This research investigated the metabolism of cocaine, methamphetamine, and morphine in common in vitro assay systems, specifically focusing on the generation of reactive intermediates and metabolites that have the potential to form covalent protein adducts. Results demonstrated the formation of covalent adduction products between biological cysteine thiols and reactive moieties on cocaine and morphine metabolites. Rigorous mass spectrometric analysis in conjunction with in vitro metabolic activation, pharmacogenetic reaction phenotyping, and computational modeling were utilized to characterize structures and mechanisms of formation for each resultant thiol adduction product. For cocaine, data collected demonstrated the formation of adduction products from a reactive arene epoxide intermediate, designating a novel metabolic pathway for cocaine. In the case of morphine, data expanded on known adduct-forming pathways using sensitive and selective analysis techniques, following the known reactive metabolite, morphinone, and a proposed novel metabolite, morphine quinone methide. Data collected in this study describe novel metabolic events for multiple important drugs of abuse, culminating in detection methods and mechanistic descriptors useful to both medical and forensic investigators when examining the toxicology associated with cocaine, methamphetamine, and morphine.

Covalent Protein Adduction by Drugs of Abuse

Recreational abuse of the drugs cocaine, methamphetamine, and morphine continues to be prevalent in the United States of America and around the world. While numerous methods of detection exist for each drug, they are generally limited by the lifetime of the parent drug and its metabolites in the body. However, the covalent modification of endogenous proteins by these drugs of abuse may act as biomarkers of exposure and allow for extension of detection windows for these drugs beyond the lifetime of parent molecules or metabolites in the free fraction. Additionally, existence of covalently bound molecules arising from drug ingestion can offer insight into downstream toxicities associated with each of these drugs. This research investigated the metabolism of cocaine, methamphetamine, and morphine in common in vitro assay systems, specifically focusing on the generation of reactive intermediates and metabolites that have the potential to form covalent protein adducts. Results demonstrated the formation of covalent adduction products between biological cysteine thiols and reactive moieties on cocaine and morphine metabolites. Rigorous mass spectrometric analysis in conjunction with in vitro metabolic activation, pharmacogenetic reaction phenotyping, and computational modeling were utilized to characterize structures and mechanisms of formation for each resultant thiol adduction product. For cocaine, data collected demonstrated the formation of adduction products from a reactive arene epoxide intermediate, designating a novel metabolic pathway for cocaine. In the case of morphine, data expanded on known adduct-forming pathways using sensitive and selective analysis techniques, following the known reactive metabolite, morphinone, and a proposed novel metabolite, morphine quinone methide. Data collected in this study describe novel metabolic events for multiple important drugs of abuse, culminating in detection methods and mechanistic descriptors useful to both medical and forensic investigators when examining the toxicology associated with cocaine, methamphetamine, and morphine.

Evaluation of clinical implications correlate to genetic polymorphisms and pharmacokinetic of transdermal fentanyl

ABSTRACT Background:Strong opioids are the treatment of choice for moderate to severe cancer-related pain. Fentanyl is a synthetic opioid with high affinity for the μ-opioid receptor and is 75–100 times more potent than morphine. Fentanyl is metabolised rapidly, particularly in the liver and only 10% is excreted as intact substance. The use of CYP3A4 inhibitors and inducers, impaired liver function, and heating of the patch potentially influence fentanyl pharmacokinetics in a clinically relevant way. The influence of BMI and gender on fentanyl pharmacokinetics is questionable. Pharmacogenetic, may influence fentanyl pharmacokinetic and other factors have been studied but did not show significant and clinically relevant effects on fentanyl pharmacokinetic. Method: This is a biological interventional prospective, single-center study in 49 patients with solid or haematological neoplasm treated with transdermal fentanyl undergoing 5-step pharmacokinetic and pharmacogenetic withdrawals from administration of the fentanyl patch. Objective:to evaluate the pharmacokinetic and pharmacogenetic of transdermal fentanyl in relation to the patient's clinical response on pain Results: Sex was the only parameter with evidence of different distribution between responders and non-responders , showing a major chance for male to be responders than females. We found some correlation with pharmacokinetic parameters and sex, regarding adverse events and NRS correlation with BPI. NAT2 and UGT2B7 polymorphisms are associated with AUC and Cmax kinetics parameters, NAT2 and CYP4F2 showed some evidence of association with the fentanyl dosage and CYP2B6 polymorphism seemed to be correlate with side effects. Conclusion: Small sample size of study population make difficult do find some significant correlation between pharmacogenetic, pharmacokinetic and clinical response. Larger studies are needed to increase knowledge about response to opioid treatment in cancer patients to better individualized pain treatment.