MDMA, methamphetamine, and CYP2D6 pharmacogenetics: what is clinically relevant?

In vitro human studies show that the metabolism of most amphetamine-like psychostimulants is regulated by the polymorphic cytochrome P450 isozyme CYP2D6. Two compounds, methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA), were selected as archetypes to discuss the translation and clinical significance of in vitro to in vivo findings. Both compounds were chosen based on their differential interaction with CYP2D6 and their high abuse prevalence in society. Methamphetamine behaves as both a weak substrate and competitive inhibitor of CYP2D6, while MDMA acts as a high affinity substrate and potent mechanism-based inhibitor (MBI) of the enzyme. The MBI behavior of MDMA on CYP2D6 implies that subjects, irrespective of their genotype/phenotype, are phenocopied to the poor metabolizer (PM) phenotype. The fraction of metabolic clearance regulated by CYP2D6 for both drugs is substantially lower than expected from in vitro studies. Other isoenzymes of cytochrome P450 and a relevant contribution of renal excretion play a part in their clearance. These facts tune down the potential contribution of CYP2D6 polymorphism in the clinical outcomes of both substances. Globally, the clinical relevance of CYP2D6 polymorphism is lower than that predicted by in vitro studies.

Clinical pharmacology of 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy"): the influence of gender and genetics (CYP2D6, COMT, 5-HTT)

The synthetic psychostimulant MDMA (±3,4-methylenedioxymethamphetamine, ecstasy) acts as an indirect serotonin, dopamine, and norepinephrine agonist and as a mechanism-based inhibitor of the cytochrome P-450 2D6 (CYP2D6). It has been suggested that women are more sensitive to MDMA effects than men but no clinical experimental studies have satisfactorily evaluated the factors contributing to such observations. There are no studies evaluating the influence of genetic polymorphism on the pharmacokinetics (CYP2D6; catechol-O-methyltransferase, COMT) and pharmacological effects of MDMA (serotonin transporter, 5-HTT; COMT). This clinical study was designed to evaluate the pharmacokinetics and physiological and subjective effects of MDMA considering gender and the genetic polymorphisms of CYP2D6, COMT, and 5-HTT. A total of 27 (12 women) healthy, recreational users of ecstasy were included (all extensive metabolizers for CYP2D6). A single oral weight-adjusted dose of MDMA was administered (1.4 mg/kg, range 75–100 mg) which was similar to recreational doses. None of the women were taking oral contraceptives and the experimental session was performed during the early follicular phase of their menstrual cycle. Principal findings show that subjects reached similar MDMA plasma concentrations, and experienced similar positive effects, irrespective of gender or CYP2D6 (not taking into consideration poor or ultra-rapid metabolizers) or COMT genotypes. However, HMMA plasma concentrations were linked to CYP2D6 genotype (higher with two functional alleles). Female subjects displayed more intense physiological (heart rate, and oral temperature) and negative effects (dizziness, sedation, depression, and psychotic symptoms). Genotypes of COMT val158met or 5-HTTLPR with high functionality (val/val or l/*) determined greater cardiovascular effects, and with low functionality (met/* or s/s) negative subjective effects (dizziness, anxiety, sedation). In conclusion, the contribution of MDMA pharmacokinetics following 1.4 mg/kg MDMA to the gender differences observed in drug effects appears to be negligible or even null. In contrast, 5-HTTLPR and COMT val158met genotypes play a major role.

Sweat testing for the detection of atomoxetine from paediatric patients with attention deficit/ hyperactivity disorder: application to clinical practice

Atomoxetine (ATX) is a selective norepinephrine reuptake inhibitor approved since 2002 for the treatment of attention deficit hyperactivity disorder (ADHD) in children, adolescents, and adults as an alternative treatment to methylphenidate. Within the framework of a project evaluating the use of alternative biological matrices for therapeutic monitoring of psychoactive drugs in paediatric and non-paediatric individuals, the excretion of ATX and its principal metabolites has been recently studied in oral fluid and hair. The aim of this study was to describe the excretion profile of ATX and its metabolites 4-hydroxyatomoxetine (4-OH-ATX) and N-desmethylatomoxetine (N-des-ATX) in sweat following the administration of different dosage regimens (60, 40, 35, and 18 mg/day) of ATX to six paediatric patients. Sweat patches were applied to the back of each participant and removed at timed intervals. ATX and its metabolites were measured in patches using a previously validated liquid chromatography-tandem mass spectrometric (LC-MS/MS) method. Independently from the administered dose, ATX appeared in the sweat patches 1 h post administration and reached its maximum concentration generally at 24 h. Peak ATX concentrations ranged between 2.31 and 40.4 ng/patch and did not correlate with the administered drug dose, or with body surface area. Total ATX excreted in sweat ranged between 0.008 and 0.121 mg, corresponding to 0.02 and 0.3% of the administered drug. Neither 4-OH-ATX, nor N-des-ATX was detected in either of the collected sweat patches. Measuring ATX in sweat patches can provide information on cumulative drug use from patch application until removal.

4-Bromo-2,5-dimethoxyphenethylamine (2C-B): presence in the recreational drug market in Spain, pattern of use and subjective effects

4-Bromo-2,5-dimethoxyphenethylamine (2C-B) is a psychoactive analogue of mescaline that is becoming increasingly popular as a rave and club drug. We investigated its presence in the illicit drug market in Spain, its pattern of use and profile of subjective effects. Drug material was analysed for 2C-B and information on pattern of use and subjective effects was obtained from recreational users. Scores were statistically compared with previously collected data on psychostimulants (d-amphetamine), entactogens (MDMA) and psychedelics (ayahuasca and Salvia divinorum). The percentage of samples containing 2C-B doubled between 2006 and 2009, evolved from powder to tablet form and showed low falsification rates. Respondents reported taking 2C-B orally in doses of about 20 mg. Subjective effects involved perceptual modifications analogous to those observed after ayahuasca and salvia but absent after amphetamine and MDMA. Pleasure and sociability effects did not differ from those after MDMA and incapacitation was lower than for the psychedelics used as comparators. In conclusion, we found 2C-B is consistently present in the illicit drug market in Spain. While it elicits perceptual modifications that are analogous to other psychedelics, the lower impairment and higher pleasurable effects make it comparable with entactogens.

Altered brain functional connectivity in relation to perception of scrutiny in social anxiety disorder

Although the fear of being scrutinized by others in a social context is a key symptom in social anxiety disorder (SAD), the neural processes underlying the perception of scrutiny have not previously been studied by functional magnetic resonance imaging (fMRI). We used fMRI to map brain activation during a perception-of-scrutiny task in 20 SAD patients and 20 controls. A multi-dimensional analytic approach was used. Scrutiny perception was mediated by activation of the medial frontal cortex, insula-operculum region and cerebellum, and the additional recruitment of visual areas and the thalamus in patients. Between-group comparison demonstrated significantly enhanced brain activation in patients in the primary visual cortex and cerebellum. Functional connectivity mapping demonstrated an abnormal connectivity between regions underlying general arousal and attention. SAD patients showed significantly greater task-induced functional connectivity in the thalamo-cortical and the fronto-striatal circuits. A statistically significant increase in task-induced functional connectivity between the anterior cingulate cortex and scrutiny-perception-related regions was observed in the SAD patients, suggesting the existence of enhanced behavior-inhibitory control. The presented data indicate that scrutiny perception in SAD enhances brain activity in arousal-attention systems, suggesting that fMRI may be a useful tool to explore such a behavioral dimension.

Unsaturated fatty alcohol derivatives of olive oil phenolic compounds with potential low-density lipoprotein (LDL) antioxidant and antiobesity properties

A new route for the synthesis of fatty alcohol derivatives of hydroxytyrosol and other olive oil phenolic compounds was developed to allow the preparation of unsaturated derivatives. The biological activity of synthesized compounds was evaluated. Most of the compounds presented a significant antioxidant activity on low-density lipoprotein (LDL) particles. The activity of the tested products was significantly influenced by the number and position of unsaturations as well as modifications on the polar head of the synthesized compounds. Some of them presented modulation of food intake in rats and, due to their molecular similarity with CB(1) endogenous ligands, the endocannabinoid system and PPAR-α were also evaluated as potential targets. The pharmacodynamics could not be totally explained by CB(1) and PPAR-α receptor interactions because only two of the four compounds with biological activity showed a CB(1) activity and all of them presented low PPAR-α affinity, not justifying its whole in vivo activity. The hydroxytyrosol linoleylether (7) increased LDL resistance to oxidation with a capacity similar to that of hydroxytyrosol and was the most active in vivo compound with a hypophagic effect comparable to that of oleoylethanolamine. We consider that this compound could be a good lead compound for future drug development in obesity treatments.

Trends in qualifying biomarkers in drug safety. Consensus of the 2011 meeting of the spanish society of clinical pharmacology

In this paper we discuss the consensus view on the use of qualifying biomarkers in drug safety, raised within the frame of the XXIV meeting of the Spanish Society of Clinical Pharmacology held in Málaga (Spain) in October, 2011. The widespread use of biomarkers as surrogate endpoints is a goal that scientists have long been pursuing. Thirty years ago, when molecular pharmacogenomics evolved, we anticipated that these genetic biomarkers would soon obviate the routine use of drug therapies in a way that patients should adapt to the therapy rather than the opposite. This expected revolution in routine clinical practice never took place as quickly nor with the intensity as initially expected. The concerted action of operating multicenter networks holds great promise for future studies to identify biomarkers related to drug toxicity and to provide better insight into the underlying pathogenesis. Today some pharmacogenomic advances are already widely accepted, but pharmacogenomics still needs further development to elaborate more precise algorithms and many barriers to implementing individualized medicine exist. We briefly discuss our view about these barriers and we provide suggestions and areas of focus to advance in the field.

Placebo response in the prophylaxis of migraine: A meta-analysis

BACKGROUND

Migraine constitutes a good model for the study of placebo response. It is a well-defined disease, affects a large population and a great number of clinical trials have been performed, which have given homogeneous outcomes.

AIM

The aim of this meta-analysis is to evaluate the placebo response rate in migraine prophylaxis in all published clinical trials since 1988 and to estimate the influence of study design in response variability.

METHODS

A computer-based information search was conducted on the Medline database. The outcomes studied were patients who improved (reduction in migraine attacks of 50% or more); attacks per month, and patients with adverse events. Study design and countries in which the study was carried out were also analysed. The meta-analysis was computed using the Mantel-Haenszel test.

RESULTS

In the final analysis, 32 papers were considered. The pooled estimate of the placebo response (patients who improved) was 21%. The placebo response rates were significantly higher in studies with a parallel design than those in cross-over studies (p<0.01). This response was also higher in European studies than in those performed in North America (p<0.001). Adverse events occurred in 30% of the patients who took a placebo, and the percentage of patients with adverse events was significantly higher in the North American studies than in those conducted in Europe (p<0.01).

CONCLUSION

These data reinforce the need to consider the placebo effect when ascertaining the true therapeutic effect of any drug, as well as to design any clinical trial in the prophylaxis of migraine.

Contribution of cytochrome P450 and ABCB1 genetic variability on methadone pharmacokinetics, dose requirements, and response

Although the efficacy of methadone maintenance treatment (MMT) in opioid dependence disorder has been well established, the influence of methadone pharmacokinetics in dose requirement and clinical outcome remains controversial. The aim of this study is to analyze methadone dosage in responder and nonresponder patients considering pharmacogenetic and pharmacokinetic factors that may contribute to dosage adequacy. Opioid dependence patients (meeting Diagnostic and Statistical Manual of Mental Disorders, [4(th) Edition] criteria) from a MMT community program were recruited. Patients were clinically assessed and blood samples were obtained to determine plasma concentrations of (R,S)-, (R) and (S)-methadone and to study allelic variants of genes encoding CYP3A5, CYP2D6, CYP2B6, CYP2C9, CYP2C19, and P-glycoprotein. Responders and nonresponders were defined by illicit opioid consumption detected in random urinalysis. The final sample consisted in 105 opioid dependent patients of Caucasian origin. Responder patients received higher doses of methadone and have been included into treatment for a longer period. No differences were found in terms of genotype frequencies between groups. Only CYP2D6 metabolizing phenotype differences were found in outcome status, methadone dose requirements, and plasma concentrations, being higher in the ultrarapid metabolizers. No other differences were found between phenotype and responder status, methadone dose requirements, neither in methadone plasma concentrations. Pharmacokinetic factors could explain some but not all differences in MMT outcome and methadone dose requirements.

Cannabis use in patients with fibromyalgia: effect on symptoms relief and health-related quality of life

Background

The aim of this study was to describe the patterns of cannabis use and the associated benefits reported by patients with fibromyalgia (FM) who were consumers of this drug. In addition, the quality of life of FM patients who consumed cannabis was compared with FM subjects who were not cannabis users.

Methods

Information on medicinal cannabis use was recorded on a specific questionnaire as well as perceived benefits of cannabis on a range of symptoms using standard 100-mm visual analogue scales (VAS). Cannabis users and non-users completed the Fibromyalgia Impact Questionnaire (FIQ), the Pittsburgh Sleep Quality Index (PSQI) and the Short Form 36 Health Survey (SF-36).

Results

Twenty-eight FM patients who were cannabis users and 28 non-users were included in the study. Demographics and clinical variables were similar in both groups. Cannabis users referred different duration of drug consumption; the route of administration was smoking (54%), oral (46%) and combined (43%). The amount and frequency of cannabis use were also different among patients. After 2 hours of cannabis use, VAS scores showed a statistically significant (p<0.001) reduction of pain and stiffness, enhancement of relaxation, and an increase in somnolence and feeling of well being. The mental health component summary score of the SF-36 was significantly higher (p<0.05) in cannabis users than in non-users. No significant differences were found in the other SF-36 domains, in the FIQ and the PSQI.

Conclusions

The use of cannabis was associated with beneficial effects on some FM symptoms. Further studies on the usefulness of cannabinoids in FM patients as well as cannabinoid system involvement in the pathophysiology of this condition are warranted.

Preliminary efficacy and safety of an oromucosal standardized cannabis extract in chemotherapy-induced nausea and vomiting

AIMS

Despite progress in anti-emetic treatment, many patients still suffer from chemotherapy-induced nausea and vomiting (CINV). This is a pilot, randomized, double-blind, placebo-controlled phase II clinical trial designed to evaluate the tolerability, preliminary efficacy, and pharmacokinetics of an acute dose titration of a whole-plant cannabis-based medicine (CBM) containing delta-9-tetrahydrocannabinol and cannabidiol, taken in conjunction with standard therapies in the control of CINV.

METHODS

Patients suffering from CINV despite prophylaxis with standard anti-emetic treatment were randomized to CBM or placebo, during the 120 h post-chemotherapy period, added to standard anti-emetic treatment. Tolerability was measured as the number of withdrawals from the study during the titration period because of adverse events (AEs). The endpoint for the preliminary efficacy analysis was the proportion of patients showing complete or partial response.

RESULTS

Seven patients were randomized to CBM and nine to placebo. Only one patient in the CBM arm was withdrawn due to AEs. A higher proportion of patients in the CBM group experienced a complete response during the overall observation period [5/7 (71.4%) with CMB vs. 2/9 (22.2%) with placebo, the difference being 49.2% (95% CI 1%, 75%)], due to the delayed period. The incidence of AEs was higher in the CBM group (86% vs. 67%). No serious AEs were reported. The mean daily dose was 4.8 sprays in both groups.

CONCLUSION

Compared with placebo, CBM added to standard antiemetic therapy was well tolerated and provided better protection against delayed CINV. These results should be confirmed in a phase III clinical trial.

Synthesis of fatty acid amides of catechol metabolites that exhibit antiobesity properties

A series of fatty acid amides of 3,4-methylenedioxymethamphetamine (MDMA) catechol metabolites were synthesized in order to evaluate their biological activities. Upon administration, all synthesized compounds resulted in negative modulation of food intake in rats. The most active compounds have affinity for the CB(1) receptor and/or PPAR-α; part of their biological activity may be caused by these double interactions.

The influence of 5-HTT and COMT genotypes on verbal fluency in ecstasy users

Deficits in verbal fluency associated with ecstasy use have been well established; however, the mechanisms underlying this impairment have yet to be elucidated. In this study we investigated for the first time whether there was a disproportionate impairment in two cognitive subcomponents of verbal fluency: clustering (ability to generate words within the same subcategory) and switching (ability to change the subcategory). We also investigated a possible association between ecstasy use and verbal fluency in subjects genotyped for 5-HTT (5-HTTLPR and 5-HTTVNTR) and COMT (val(108/158)met, rs165599 and rs2097603) polymorphisms, in order to find a potential implication of genetic factors. Ecstasy polydrug users (n = 30) and non-ecstasy users (n = 41) were evaluated in both semantic and phonemic fluency. Results showed that ecstasy users had poorer semantic (but not phonemic) fluency performance than controls. Detailed analysis of clustering and switching performance revealed that this impairment was associated with poorer clustering mechanisms. Clustering was also modulated by the COMT rs165599 polymorphism independently of the group. A specific effect of the 5-HTTLPR polymorphism on switching performance was also found, with ss carriers performing significantly worse than ls and ll carriers, suggesting a serotonin modulation of frontal-executive flexibility. Based on the impaired clustering and switching strategies observed in ecstasy users, it might be proposed that both semantic knowledge and retrieval are impaired in this population. The verbal fluency deficit in ecstasy users may be attributable to a disruption of frontal-striatal circuits directly related with the serotonin function as well as a depletion of lexical-semantic stores mediated by temporal structures.

Errors and reproducibility of DNA array-based detection of allelic variants in ADME genes: PHARMAchip™

Aims: Differences in adverse drug reactions can be explained by genetic variations, especially if they determine the expression of certain protein effectors and/or drug-metabolizing enzymes. Over the last decade, several tests screening for the most frequent polymorphisms in drug-metabolizing enzymes have been marketed for research and diagnostic purposes. The aim of this study was to assess the suitability of PHARMAchip™ for the genotyping of polymorphisms of genes associated with drug metabolism and response as an alternative to Jurilab Ltd’s DrugMEt® Test. Materials & methods: In this observational study, performed using 100 previously genotyped DNA samples, we report on common genes included in the two different tests examined: the former DrugMEt test and the recently introduced PHARMAchip test. Results & conclusion: Although these tests are based on different methodological approaches, we have found a high concordance of results between both methods. Some of the discrepancies between tests were related to allelic variants not monitored in a particular microarray and the quality of the genomic DNA used.

5-HTTLPR polymorphism, mood disorders and MDMA use in a 3-year follow-up study

A 3-year longitudinal prospective study was conducted to compare the incidence of substance use disorders (SUD) and non-substance use disorders (NSUD) among ecstasy users and two control groups: one of cannabis users and the other of non-drug users. The 5-HTTLPR polymorphism related to NSUD was also studied. A total of 94 subjects were included: 37 ecstasy users, 23 cannabis users and 34 non-drug users. SUD and NSUD disorders were diagnosed according to the fourth edition of the Diagnostic and Statistical Manual of Mental Health Disorders criteria using the Psychiatric Research Interview for Substance and Mental Disorders. Incidence Rates (IR) are presented. The 5-HTTLPR polymorphism was analyzed. Hardy-Weinberg equilibrium was studied. The results of the study showed that the highest IR of SUD was cannabis abuse/dependence in both the ecstasy (IR: 48.6/100 person-year) and cannabis (IR: 2.5/100 person-year) groups. There were no new cases of SUD in non-drug users at follow-up. The highest IR of NSUD was primary mood disorder in both the ecstasy (IR: 4.2/100 person-year) and in the non-drug (IR: 1.3/100 person-year) groups (P < 0.282). There were no new cases of NSUD in the cannabis group at follow-up. 5-HTTLPR polymorphism was associated with lifetime of primary mood disorders in ecstasy group (P = 0.018). Ecstasy use was associated with a higher rate of cannabis abuse/dependence disorders and mood disorders than cannabis use. In the ecstasy users, 5-HTTLPR polymorphism may result in a high vulnerability to primary mood disorders.

Alcohol consumption is associated with high concentrations of urinary hydroxytyrosol

BACKGROUND

Previously, we reported the presence of hydroxytyrosol in red wine and higher human urinary recovery of total hydroxytyrosol than that expected after a single red wine intake. We hypothesized that the alcohol present in wine could promote endogenous hydroxytyrosol generation.

OBJECTIVE

The objective was to assess the relation between alcohol consumption and urinary hydroxytyrosol concentrations.

DESIGN

This was a cross-sectional study with baseline data from a subsample of the PREvención con DIeta MEDiterránea (PREDIMED) trial, an intervention study directed at testing the efficacy of the Mediterranean diet on the primary prevention of cardiovascular disease. Participants included 1045 subjects, aged 55-80 y, who were at high cardiovascular risk. Alcohol consumption was estimated through a validated food-frequency questionnaire. Urinary hydroxytyrosol and ethyl glucuronide, a biomarker of alcohol consumption, were measured.

RESULTS

Urinary ethyl glucuronide concentrations were directly related to alcohol and wine consumption (P < 0.001) as well as to urinary hydroxytyrosol in both sexes (P < 0.001). The degree of alcohol consumption was directly associated with urinary hydroxytyrosol in male alcohol consumers (P < 0.001). Multivariate logistic regression analyses showed a significant linear trend (P < 0.05) for elevated hydroxytyrosol concentrations with an increase in alcohol consumption. Intakes of >20 g (2 drinks)/d and >10 g (1 drink)/d alcohol in men and women, respectively, were associated (P < 0.05) with elevated concentrations of hydroxytyrosol.

CONCLUSIONS

We report for the first time a direct association between urinary hydroxytyrosol and alcohol consumption at a population level. These findings reinforce previous work in human and animal models that examines wine as a source of hydroxytyrosol and alcohol as an indirect promoter of endogenous hydroxytyrosol generation. This trial was registered at controlled-trials.com/isrctn/ as ISRCTN 35739639.