Pharmacodynamic evaluation of the cardiovascular effects after the coadministration of cocaine and ethanol

Short-term standard alcohol consumption enhances platelet response to clopidogrel through inhibition of Nrf2/Ces1 pathway and induction of Cyp2c in mice

AIMS

Drinking alcohol is prevalent worldwide; however, it is unknown whether alcohol could affect the antiplatelet effects of clopidogrel in patients when taking both concomitantly. This study was designed to investigate the influence of short-term standard alcohol consumption on the metabolic activation of and platelet response to clopidogrel in mice as well as the mechanisms involved.

MAIN METHODS

Male C57BL/6J mice were administered with normal saline (vehicle control) or alcohol at 2 g/kg/day for 7 days, and then gavaged with vehicle control or a single dose of clopidogrel at 10 mg/kg. Inhibition of ADP-induced platelet aggregation and activation by clopidogrel, plasma concentrations of clopidogrel and its active metabolite H4, and changes in mRNA and protein expression of genes related to clopidogrel metabolism and its regulation were measured in mice pretreated with or without alcohol.

KEY FINDINGS

Compared with vehicle control, alcohol pretreatment significantly reduced hydrolysis of clopidogrel as a result of significant down-regulation of Nrf2-mediated Ces1 expression (responsible for the formation of clopidogrel carboxylate), increased metabolic activation of clopidogrel due to significant up-regulation of Cyp2c (for the formation of active thiol metabolite H4), and consequently enhanced inhibition of ADP-induced platelet aggregation and activation by clopidogrel.

SIGNIFICANCE

Short-term standard alcohol consumption would significantly enhance suppression of ADP-induced platelet aggregation and activation by clopidogrel through significant inhibition of Nrf2/Ces1 signaling pathway and induction of Cyp2c, suggesting that alcohol may interact with drugs that are predominantly metabolized by CES1 or CYP2C in patient care, including clopidogrel.

Application of Pharmacokinetic-Pharmacodynamic Modeling in Drug Delivery: Development and Challenges

With the advancement of technology, drug delivery systems and molecules with more complex architecture are developed. As a result, the drug absorption and disposition processes after administration of these drug delivery systems and engineered molecules become exceedingly complex. As the pharmacokinetic and pharmacodynamic (PK-PD) modeling allows for the separation of the drug-, carrier- and pharmacological system-specific parameters, it has been widely used to improve understanding of the in vivo behavior of these complex delivery systems and help their development. In this review, we summarized the basic PK-PD modeling theory in drug delivery and demonstrated how it had been applied to help the development of new delivery systems and modified large molecules. The linkage between PK and PD was highlighted. In particular, we exemplified the application of PK-PD modeling in the development of extended-release formulations, liposomal drugs, modified proteins, and antibody-drug conjugates. Furthermore, the model-based simulation using primary PD models for direct and indirect PD responses was conducted to explain the assertion of hypothetical minimal effective concentration or threshold in the exposure-response relationship of many drugs and its misconception. The limitations and challenges of the mechanism-based PK-PD model were also discussed.

Ethanol addictively enhances the in vitro cardiotoxicity of cocaine through oxidative damage, energetic deregulation, and apoptosis

Cocaine (COC) is frequently consumed in polydrug abuse settings, and ethanol (EtOH) is the most prominent co-abused substance. Clinical data and experimental evidence suggest that the co-administration of COC with EtOH can be more cardiotoxic than EtOH or COC alone, but information on the molecular pathways involved is scarce. Since these data are crucial to potentiate the identification of therapeutic targets to treat intoxications, we sought to (i) elucidate the type of interaction that occurs between both substances, and (ii) assess the mechanisms implicated in the cardiotoxic effects elicited by COC combined with EtOH. For this purpose, H9c2 cardiomyocytes were exposed to COC (104 µM-6.5 mM) and EtOH (977 µM-4 M), individually or combined at a molar ratio based on blood concentrations of intoxicated abusers (COC 1: EtOH 9; 206 µM-110 mM). After 24 h, cell metabolic viability was recorded by the MTT assay and mixture toxicity expectations were calculated using the independent action (IA) and concentration addition (CA) models. EtOH (EC₅₀ 305.26 mM) proved to act additively with COC (EC₅₀ 2.60 mM) to significantly increase the drug in vitro cardiotoxicity, even when both substances were combined at individually non-cytotoxic concentrations. Experimental mixture testing (EC₅₀ 19.18 ± 3.36 mM) demonstrated that the cardiotoxicity was fairly similar to that predicted by IA (EC₅₀ 22.95 mM) and CA (EC₅₀ 21.75 mM), supporting additivity. Concentration-dependent increases of intracellular ROS/RNS and GSSG, depletion of GSH and ATP, along with mitochondrial hyperpolarization and activation of intrinsic, extrinsic, and common apoptosis pathways were observed both for single and combined exposures. In general, the mixture exhibited a toxicological profile that mechanistically did not deviate from the single drugs, suggesting that interventions such as antioxidant administration might aid in the clinical treatment of this type of polydrug intoxication. In a clinical perspective, the observed additive mixture effect may reflect the increased hazards at which users of this combination are exposed to in recreational settings.

The usefulness of biomarkers of alcohol abuse in hair and serum carbohydrate-deficient transferrin: a case report

The detection of carbohydrate-deficient transferrin (CDT) in serum is widely accepted to identify chronic alcohol consumption over the previous two weeks, but minor ethanol metabolites detected in hair often complete the information obtained. In particular, ethylglucuronide and cocaethylene (a marker of simultaneous intake of cocaine and alcohol) allow correct interpretation of data obtained in forensic cases. We refer to a negative CDT value obtained from a serum sample collected during hospitalization of a man admitted for cardiac arrest who died about 14 h later. Clinical analysis performed on admission showed a high ethanol level and a positive urinary screening for cocaine. The toxicological analyses of post-mortem samples found cocaine metabolites in his urine and blood. The negative CDT level suggested the ethanol concentration at admission to be an acute episode. Cocaine and cocaethylene well above the cut-off suggested by the literature were found in hair analyzed for the entire length (about 1 cm). Ethylglucuronide detected on the same hair sample confirmed chronic abuse of ethanol in the previous month, at least. The present report suggests caution in the interpretation of biomarkers of alcohol abuse, encouraging the detection of more than one marker to avoid misinterpretation.

Cocaine-associated increase of atrial natriuretic peptides: an early predictor of cardiac complications in cocaine users?

OBJECTIVE

Cocaine is known to produce life-threatening cardiovascular complications, and the investigation of the causes of death may be challenging in forensic medicine. The increasing knowledge of the cardiac function biomarkers and the increasing sensitivity of assays provide new tools in monitoring the cardiac life-threatening pathological conditions and in the sudden death investigation in chronic abusers. In this work, cardiac dysfunction was assessed in an animal model by measuring troponin I and natriuretic peptides as biomarkers, and considering other standard endpoints used in preclinical toxicology studies.

METHODS

Lister Hooded rats were treated with cocaine in chronic self-administration studies. Troponin I (cTnI) and atrial natriuretic peptide (ANP) were evaluated at different time points and heart weight and histopathology were assessed at the end of the treatment period. Furthermore, cocaine and its main metabolites were measured in the rat fur to assess rats' cocaine exposure. All the procedures and endpoints considered were designed to allow an easy and complete translation from the laboratory animals to human beings, and the same approach was also adopted with a group of 10 healthy cocaine abuse volunteers with no cardiac pathologies.

RESULTS

Cardiac troponin I values were unaffected, and ANP showed an increasing trend with time in all cocaine-treated animals considered. Similarly, in the healthy volunteers, no changes were observed in troponin serum levels, whereas the N-terminal brain natriuretic pro-peptide (NT proBNP) showed variations comparable with the changes observed in rats.

CONCLUSIONS

In conclusion, natriuretic peptides could represent an early indicator of heart dysfunction liability in chronic cocaine abusers.

Onset of cocaine use: associated alcohol intoxication and psychosocial characteristics among adolescents in substance abuse treatment

OBJECTIVES

Cocaine abuse is widespread in Europe, and Ireland ranks among the leading countries for prevalence of cocaine use among adolescents. This study aimed to examine demographic and substance use correlates of lifetime cocaine use among adolescents with substance use disorder, and to explore the relationship between alcohol intoxication and cocaine initiation.

METHODS

Data from a cross-sectional study of 171 adolescents presenting to an outpatient substance abuse treatment program in the Dublin metropolitan area were analyzed. Bivariate and multivariate analyses were conducted.

RESULTS

Approximately 64% of the participants reported ever used cocaine: 70% reported the first use of cocaine was while alcohol intoxicated and 96% reported the onset of cocaine use was preceded by cannabis use. Later age at treatment entry, unstable accommodation, non engagement in educational/vocational functions, and greater frequency of alcohol and cannabis use had robust associations with lifetime cocaine use. Male gender was significantly associated with first use of cocaine while alcohol intoxicated.

CONCLUSIONS

Alcohol frequently plays a central role in cocaine initiation in Irish adolescents. Efforts to delay, avoid, or reduce adolescent drinking may yield benefits in terms of reducing cocaine use initiation in this population.

Mechanism-based pharmacodynamic modeling

Pharmacodynamic modeling is based on a quantitative integration of pharmacokinetics, pharmacological systems, and (patho-) physiological processes for understanding the intensity and time-course of drug effects on the body. Application of such models to the analysis of meaningful experimental data allows for the quantification and prediction of drug-system interactions for both therapeutic and adverse drug responses. In this chapter, commonly used mechanistic pharmacodynamic models are presented with respect to their important features, operable equations, and signature profiles. In addition, literature examples showcasing the utility of these models to adverse drug events are highlighted. Common model types that are covered include simple direct effects, biophase distribution, indirect effects, signal transduction, and irreversible effects.