Coverage of Sex Acts by Event-Driven Pre-exposure Prophylaxis: A Sub-Study of the ANRS IPERGAY Trial.

We assessed the coverage of sex acts by event-driven pre-exposure prophylaxis (ED-PrEP) over a 2-month period in 54 participants in the open label phase of the ANRS Ipergay trial. Participants received an electronic monitoring system device to record bottle openings. Self-questionnaires collected daily information on PrEP intake and sexual behavior. Intake was also estimated through returned pill counts. Full coverage of sex acts was defined as at least one pill taken both within 24 h before and within 48 h following sex. There was a strong correlation (r = - 0.92) between the number of bottle openings and returned pill counts. During the study, 42 participants (78%) practiced ED-PrEP and 12 (22%) daily PrEP with bottle openings at least 5 days/week whatever their sexual activity. Out of the 154 reported receptive anal sex acts, 81% were condomless: among them, PrEP coverage was hight: 97% among those practicing daily PrEP and 82% among those using ED-PrEP.

On-Demand Preexposure Prophylaxis in Men at High Risk for HIV-1 Infection.

BACKGROUND: Antiretroviral preexposure prophylaxis has been shown to reduce the risk of human immunodeficiency virus type 1 (HIV-1) infection in some studies, but conflicting results have been reported among studies, probably due to challenges of adherence to a daily regimen. METHODS: We conducted a double-blind, randomized trial of antiretroviral therapy for preexposure HIV-1 prophylaxis among men who have unprotected anal sex with men. Participants were randomly assigned to take a combination of tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) or placebo before and after sexual activity. All participants received risk-reduction counseling and condoms and were regularly tested for HIV-1 and HIV-2 and other sexually transmitted infections. RESULTS: Of the 414 participants who underwent randomization, 400 who did not have HIV infection were enrolled (199 in the TDF-FTC group and 201 in the placebo group). All participants were followed for a median of 9.3 months (interquartile range, 4.9 to 20.6). A total of 16 HIV-1 infections occurred during follow-up, 2 in the TDF-FTC group (incidence, 0.91 per 100 person-years) and 14 in the placebo group (incidence, 6.60 per 100 person-years), a relative reduction in the TDF-FTC group of 86% (95% confidence interval, 40 to 98; P=0.002). Participants took a median of 15 pills of TDF-FTC or placebo per month (P=0.57). The rates of serious adverse events were similar in the two study groups. In the TDF-FTC group, as compared with the placebo group, there were higher rates of gastrointestinal adverse events (14% vs. 5%, P=0.002) and renal adverse events (18% vs. 10%, P=0.03). CONCLUSIONS: The use of TDF-FTC before and after sexual activity provided protection against HIV-1 infection in men who have sex with men. The treatment was associated with increased rates of gastrointestinal and renal adverse events. (Funded by the National Agency of Research on AIDS and Viral Hepatitis [ANRS] and others; ClinicalTrials.gov number, NCT01473472.).

Single-dose pharmacokinetics and pharmacodynamics of oral tenofovir and emtricitabine in blood, saliva and rectal tissue: a sub-study of the ANRS IPERGAY trial.

OBJECTIVES: In the ANRS IPERGAY pre-exposure prophylaxis (PrEP) trial, a single dose of tenofovir disoproxil fumarate and emtricitabine was taken orally 2-24 h before sexual intercourse. A sub-study was conducted to assess the pharmacokinetics of tenofovir and emtricitabine in blood, saliva and rectal tissue following this initial oral intake. METHODS: Plasma, PBMC, saliva and rectal tissue sampling was performed over 24 h in 12 seronegative men before enrolment in the ANRS IPERGAY trial, following a single dose of 600 mg tenofovir disoproxil fumarate/400 mg emtricitabine. Ex vivo HIV infectibility of rectal biopsies was also assessed. RESULTS: The median plasma Tmax of tenofovir (median Cmax: 401 µg/L) and emtricitabine (median Cmax: 2868 µg/L) was obtained 1 h (range: 0.5-4) and 2 h (range: 1-4) after dosing, respectively. The median C24 of tenofovir and emtricitabine was 40 and 63 µg/L, respectively. The median PBMC tenofovir diphosphate and emtricitabine triphosphate levels were 12.2 and 16.7 fmol/106 cells and 2800 and 2000 fmol/106 cells at 2 and 24 h after dosing, respectively. Saliva/plasma AUC0-24 ratios were 2% and 17% for tenofovir and emtricitabine, respectively. Emtricitabine was detected in rectal tissue 30 min after dosing, whereas tenofovir was only detectable at 24 h. Ex vivo HIV infectibility assays of rectal biopsies showed partial protection after dosing (P < 0.07). DISCUSSION: A single high dose of oral tenofovir disoproxil fumarate/emtricitabine provides rapid and high blood levels of tenofovir and emtricitabine, with rapid diffusion of emtricitabine in saliva and rectal tissue.

Concentrations of tenofovir and emtricitabine in saliva: implications for preexposure prophylaxis of oral HIV acquisition.

To prevent acquisition of HIV through oral sex, drugs used for preexposure prophylaxis (Prep) need to diffuse in saliva. We measured tenofovir (TFV) and emtricitabine (FTC) concentrations simultaneously in the plasma and saliva of 41 HIV-infected patients under stable antiretroviral treatment. Mean ratios of saliva/plasma concentration were 3% (±4%) and 86.9% (±124%) for TFV and FTC, respectively. Tenofovir disoproxil fumarate (TDF) should be used in combination with FTC to prevent oral acquisition of HIV.

Ascorbic Acid Deficiency Prevalence and Associated Cognitive Impairment in Alcohol Detoxification Inpatients: A Pilot Study.

Malnutrition has been reported in alcohol use disorder patients as having a possible influence on cognitive function. The aim of this study was to analyse the prevalence of ascorbic acid (AA) deficiency in inpatients admitted for alcohol detoxification and the associated factors, including cognitive impairment in the early period of abstinence. A retrospective chart review was conducted. The AA level was categorised into three groups: deficiency (AAD) (<2 mg/L), insufficiency (AAI) (2-5 mg/L) and normal level. The cognitive impairment was screened using the Montreal Cognitive Assessment (MoCA). Ninety-six patients were included (74 men; mean age 49.1 years (±11.5)). Twenty-seven AAD (28.1%) and twenty-two AAI (22.9%) were observed. In multivariate analysis, risk factors for AAD versus normal AA level were men (OR 17.8, 95%CI (1.63-194)), compensated cirrhosis (OR 9.35, 95%CI (1.60-54.6)) and street homelessness (OR 5.76, 95%CI (1.24-26.8) versus personal housing). The MoCA score was available for 53 patients (mean MoCA score: 25.7 (±3.3)). In multivariate analysis, the natural logarithm of AA (ß = 1.18, p = 0.037) and sedative use disorder (ß = -2.77, p = 0.046) were associated with the MoCA score. AAD and AAI are frequent in inpatients admitted for alcohol detoxification. A low level of AA was associated with cognitive impairment in the early period of abstinence.

Sprague-Dawley rats display sex-linked differences in the pharmacokinetics of 3,4-methylenedioxymethamphetamine (MDMA) and its metabolite 3,4-methylenedioxyamphetamine (MDA).

The use of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) has increased in recent years; it can lead to life-threatening hyperthermia and serotonin syndrome. Human and rodent males appear to be more sensitive to acute toxicity than are females. MDMA is metabolized to five main metabolites by the enzymes CYP1A2, CYP2D and COMT. Little is presently known about sex-dependent differences in the pharmacokinetics of MDMA and its metabolites. We therefore analyzed MDMA disposition in male and female rats by measuring the plasma and urine concentrations of MDMA and its metabolites using a validated LC-MS method. MDA AUC(last) and C(max) were 1.6- to 1.7-fold higher in males than in females given MDMA (5 mg/kg sc), while HMMA C(max) and AUC(last) were 3.2- and 3.5-fold higher, respectively. MDMA renal clearance was 1.26-fold higher in males, and that of MDA was 2.2-fold higher. MDMA AUC(last) and t(1/2) were 50% higher in females given MDMA (1 mg/kg iv). MDA C(max) and AUC(last) were 75-82% higher in males, with a 2.8-fold higher metabolic index. Finally, the AUC(last) of MDA was 0.73-fold lower in males given 1 mg/kg iv MDA. The volumes of distribution of MDMA and MDA at steady-state were similar in the two sexes. These data strongly suggest that differences in the N-demethylation of MDMA to MDA are major influences on the MDMA and MDA pharmacokinetics in male and female rats. Hence, males are exposed to significantly more toxic MDA, which could explain previously reported sexual dysmorphism in the acute effects and toxicity of MDMA in rats.

Post-exposure prophylaxis with doxycycline to prevent sexually transmitted infections in men who have sex with men: an open-label randomised substudy of the ANRS IPERGAY trial.

BACKGROUND: Increased rates of sexually transmitted infections (STIs) have been reported among men who have sex with men. We aimed to assess whether post-exposure prophylaxis (PEP) with doxycycline could reduce the incidence of STIs. METHODS: All participants attending their scheduled visit in the open-label extension of the ANRS IPERGAY trial in France (men aged 18 years or older having condomless sex with men and using pre-exposure prophylaxis for HIV with tenofovir disoproxil fumarate plus emtricitabine) were eligible for inclusion in this open-label randomised study. Participants were randomly assigned (1:1) at a central site to take a single oral dose of 200 mg doxycycline PEP within 24 h after sex or no prophylaxis. The primary endpoint was the occurrence of a first STI (gonorrhoea, chlamydia, or syphilis) during the 10-month follow-up. The cumulative probability of occurrence of the primary endpoint was estimated in each group with the Kaplan-Meier method and compared with the log-rank test. The primary efficacy analysis was done on the intention-to-treat population, comprising all randomised participants. All participants received risk-reduction counselling and condoms, and were tested regularly for HIV. This trial is registered with ClinicalTrials.gov number, NCT01473472. FINDINGS: Between July 20, 2015, and Jan 21, 2016, we randomly assigned 232 participants (n=116 in the doxycycline PEP group and n=116 in the no-PEP group) who were followed up for a median of 8·7 months (IQR 7·8-9·7). Participants in the PEP group used a median of 680 mg doxycycline per month (IQR 280-1450). 73 participants presented with a new STI during follow-up, 28 in the PEP group (9-month probability 22%, 95% CI 15-32) and 45 in the no-PEP group (42%, 33-53; log-rank test p=0·007). The occurrence of a first STI in participants taking PEP was lower than in those not taking PEP (hazard ratio [HR] 0·53; 95% CI 0·33-0·85; p=0·008). Similar results were observed for the occurrence of a first episode of chlamydia (HR 0·30; 95% CI 0·13-0·70; p=0·006) and of syphilis (0·27; 0·07-0·98; p=0·047); for a first episode of gonorrhoea the results did not differ significantly (HR 0·83; 0·47-1·47; p=0·52). No HIV seroconversion was observed, and 72 (71%) of all 102 STIs were asymptomatic. Rates of serious adverse events were similar in the two study groups. Gastrointestinal adverse events were reported in 62 (53%) participants in the PEP group and 47 (41%) in the no-PEP group (p=0·05). INTERPRETATION: Doxycycline PEP reduced the occurrence of a first episode of bacterial STI in high-risk men who have sex with men. FUNDING: France Recherche Nord & Sud Sida-HIV Hépatites (ANRS) and Bill & Melinda Gates Foundation.

Determination of ketamine and its main metabolites by liquid chromatography coupled to tandem mass spectrometry in pig plasma: Comparison of extraction methods.

A rapid, sensitive and specific liquid chromatography coupled to tandem mass spectrometry method was developed for the simultaneous quantification pig plasma of ketamine and its two principal metabolites, norketamine and dehydronorketamine. Three extraction procoles were assessed including acetonitrile precipitation, Oase™ microplate extraction, and liquid-liquid extraction. Oase™ microplate extraction induced no significant matrix effect, important signal/noise ratio and good recoveries, ranging from 82 to 87% for the considered compounds. Using this extraction procedure, the assay was linear in the dynamic range 10-3000ng/mL (R2>0.99) regardless of the analytes. Intra- and inter-day accuracies were less than 12% for all compounds and intra- and inter-day precisions expressed as RSD were within <9.9%. Samples were stable in different storage conditions. High ketamine, norketamine and dehydronorketamine concentrations up to 15,000ng/mL can be determined with good precision using appropriate sample dilution. The assay was successfully applied to pig plasma samples to determine the pharmacokinetics of ketamine and the consecutive metabolites after buccal administration of a 4mg/kg ketamine base solutions.

Efficacy, safety, and effect on sexual behaviour of on-demand pre-exposure prophylaxis for HIV in men who have sex with men: an observational cohort study.

BACKGROUND: Data for on-demand pre-exposure prophylaxis (PrEP) are scarce. We implemented a cohort study to assess its efficacy, safety, and effect on sexual behaviour. METHODS: We invited men and transgender women who have sex with men, previously enrolled in the randomised placebo-controlled ANRS IPERGAY trial at seven sites (six in France and one in Canada), to participate in an open-label extension with on-demand tenofovir disoproxil fumarate (300 mg) and emtricitabine (200 mg) to be taken before and after sexual intercourse. We assessed the incidence of HIV and other sexually transmitted infections (STIs), PrEP adherence, safety, and sexual behaviour. Statistical analyses included comparisons of proportions and incidence between the randomised phase of the ANRS IPERGAY trial and the open-label phase, and all participants were included in safety analyses. ANRS IPERGAY is registered with ClinicalTrials.gov, number NCT01473472. FINDINGS: Between Nov 4, 2014, and Jan 27, 2015, we enrolled 361 participants. Median follow-up was 18·4 months (IQR 17·7-19·1). One participant who discontinued PrEP acquired HIV infection. HIV incidence was 0·19 per 100 person-years (95% CI 0·01-1·08), compared with 6·60 per 100 person-years (3·60-11·05) in the placebo group of the randomised study, indicating a relative reduction of 97% (95% CI 81-100) in the incidence of HIV with on-demand PrEP. Participants used a median of 18 pills of study drugs per month (IQR 11-25), and at the 6 month visit 240 (71%) of 336 participants had tenofovir detected in plasma. Drug-related gastrointestinal events were reported in 49 participants (14%) but were self-limited. Only four participants (1%) discontinued PrEP, three because of an increase in plasma creatinine. The proportion of participants reporting condomless sex at their last receptive anal intercourse significantly increased from 77% (136 of 176 participants) at baseline to 86% (66 of 77 participants) at 18 months' follow-up (p for trend=0·0004). The incidence of a first bacterial STI during this open-label phase did not change significantly compared with the randomised phase (59·0 vs 49·1 per 100 person-years, respectively; p=0·11). INTERPRETATION: On-demand oral PrEP is highly effective at preventing HIV infection among high-risk men who have sex with men and therefore represents an alternative to daily PrEP, expanding choices for HIV prevention. High rates of STIs resulting from low condom use did not undermine PrEP efficacy, but warrant frequent testing. FUNDING: ANRS (France Recherche Nord and Sud Sida-HIV Hépatites), the Canadian HIV Trials Network, Fonds Pierre Bergé-Sidaction, Gilead Sciences, and the Bill & Melinda Gates Foundation.

Efficacy and safety of a switch to rilpivirine-based regimens in treatment-experienced HIV-1-infected patients: a cohort study.

BACKGROUND: Rilpivirine (RPV) is a second-generation once-daily non-nucleoside reverse transcriptase inhibitor (NNRTI) which has shown non-inferior antiviral activity to efavirenz in treatment-naive patients. Data in treatment-experienced patients are more limited. We wished to assess the efficacy and safety of a switch to RPV-based regimens in well-suppressed treatment-experienced patients. METHODS: Between September 2012 and June 2013, all antiretroviral therapy (ART)-experienced HIV-1-infected patients with a plasma HIV RNA level <50 copies/ml, and switching to an RPV-based regimen, were analysed in this retrospective observational monocentric cohort study. The primary end point was the proportion of patients with virological success defined as a plasma HIV RNA level <50 copies/ml at 12 months using the FDA snapshot algorithm. RESULTS: A total of 281 participants were studied and 97% received a combination of RPV/tenofovir disoproxil fumarate/emtricitabine. At month 12, the rate of virological success was 59% and increased to 72% using available data beyond month 12. Sixteen (6%) patients experienced virological failure, which was associated with the presence of the M184V/I resistance mutation in prior genotypes (P=0.02) and the use of a non-NNRTI as third agent before the switch (P=0.03). RPV-based regimens were overall well tolerated and only 23 (8%) patients discontinued ART because of adverse events, mostly neuropsychiatric adverse events. Switching to RPV was associated with significant but modest improvement of the lipid profile. CONCLUSIONS: In patients fully suppressed on ART, a switch to an RPV-based regimen should only be considered in the absence of prior virological failure or resistance mutations to nucleoside reverse transcriptase inhibitors and NNRTIs to avoid virological failures.

Early changes in coagulation but not inflammatory biomarkers under intermittent ART: the randomized ANRS 106 WINDOW trial.

INTRODUCTION: In the SMART trial, baseline plasma hsCRP, IL6 and D-dimer levels were strongly correlated to all-cause mortality. A case-control study has shown an increase of IL-6 and D-dimer levels after one month of antiretroviral therapy (ART) interruption, which was correlated to viral load. Restarting ART was associated to a decrease in D-dimer but not IL-6 or hsCRP levels. We assessed biomarkers levels up to 96 weeks in ART-experienced adults with plasma HIV RNA levels <400 c/mL randomized in the ANRS 106 WINDOW trial to intermittent ART (IT: six cycles of eight weeks of ART interruption followed by eight weeks of ART) versus continuous treatment (CT). METHODS: Stored plasma for 160 participants (80 IT and 80 CT), matched by age, sex and CDC classification, were analyzed blinded for IL-6, sCD-14, hsCRP and D-dimer levels at baseline, week 8 (IT group only), week 16 and week 96. Lower levels of detection for IL-6, sCD14, hsCRP and D-Dimer were 1.5 pg/mL, 250 ng/mL, 0.03 µg/mL and 0.21 µg/mL, respectively. The primary objective was to compare changes in IL-6, hsCRP, sCD14 and D-dimer plasma levels from baseline to week 8, 16 and 96 in the IT and CT arms. Biomarkers levels were log10 transformed prior to analysis. RESULTS: At baseline, patients were mostly men (86%), with a median age of 40 years, a CD4+ T-cell count of 768/mm(3), have received a median of 4.7 years of ART and 85% had HIV RNA <50 c/mL. Proportion of patients with plasma HIV RNA levels<400 c/mL were 6% and 99%, 81% and 97%, 86% and 92% at weeks 8, 16 and 96 in the IT and CT arms, respectively. Plasma biomarkers levels are shown in the Table 1. CONCLUSION: Coagulation and inflammatory biomarkers levels remained stable over 96 weeks in well-suppressed HIV-infected patient on ART. Following ART interruption there was a significant increase in D-dimer but not in inflammatory biomarkers levels. This increase was reversed upon reintroduction of ART. These data suggest that ART interruption increases coagulation rather than inflammatory biomarkers.

Development, validation and clinical application of a LC-MS/MS method for the simultaneous quantification of hydroxychloroquine and its active metabolites in human whole blood.

A rapid, sensitive and specific method using liquid chromatography coupled to tandem mass spectrometry was developed for the simultaneous quantification of hydroxychloroquine (HCQ) and its three major metabolites in human whole blood. The assay, using a sample volume of 100µL, was linear in a dynamic 25-2000ng/mL range (R(2)>0.99) for all four compounds and suitable for the determination of elevated HCQ concentrations up to 20,000ng/mL, after appropriate sample dilution. Inter- and intra-assay precisions were <18.2% and accuracies were between 84% and 113% for any analyte. No matrix effects were observed. The assay was successfully applied to a blood sample obtained from one poisoned patient following a massive HCQ self-ingestion resulting in an estimated concentration of 19,500ng/mL on hospital admission. In this patient, HCQ metabolites were identified and quantified at 1123, 465 and 91ng/mL for monodesethylhydroxychloroquine, desethylchloroquine and bisdesethylchloroquine, respectively. Further investigations are still required to assess the usefulness of the simultaneous measurement of blood concentrations of HCQ and its three active metabolites for monitoring HCQ treatment and managing HCQ poisoning.

Uncoupling RARA transcriptional activation and degradation clarifies the bases for APL response to therapies.

In PML/RARA-driven acute promyelocytic leukemia (APL), retinoic acid (RA) induces leukemia cell differentiation and transiently clears the disease. Molecularly, RA activates PML/RARA-dependent transcription and also initiates its proteasome-mediated degradation. In contrast, arsenic, the other potent anti-APL therapy, only induces PML/RARA degradation by specifically targeting its PML moiety. The respective contributions of RA-triggered transcriptional activation and proteolysis to clinical response remain disputed. Here, we identify synthetic retinoids that potently activate RARA- or PML/RARA-dependent transcription, but fail to down-regulate RARA or PML/RARA protein levels. Similar to RA, these uncoupled retinoids elicit terminal differentiation, but unexpectedly fail to impair leukemia-initiating activity of PML/RARA-transformed cells ex vivo or in vivo. Accordingly, the survival benefit conferred by uncoupled retinoids in APL mice is dramatically lower than the one provided by RA. Differentiated APL blasts sorted from uncoupled retinoid-treated mice retain PML/RARA expression and reinitiate APL in secondary transplants. Thus, differentiation is insufficient for APL eradication, whereas PML/RARA loss is essential. These observations unify the modes of action of RA and arsenic and shed light on the potency of their combination in mice or patients.

Determination of 3,4-methylenedioxymethamphetamine and its five main metabolites in rat urine by solid-phase extraction and high performance liquid chromatography with on line mass spectrometry.

The consumption of psychostimulant amphetamine-like drugs has increased significantly in recent years. Some MDMA metabolites are probably involved in the neurotoxicity and neurodegeneration caused by prolonged use rather than MDMA itself. We recently developed a method to analyze MDMA and its five main metabolites in rat plasma [7]. We have now fully validated this method to the quantification of these drugs in rat urine. We extracted MDMA and its metabolites with Oasis WCX cartridges, separated them on a Nucleodur C18 analytical column and quantified them by ion-trap mass spectrometry. Linearity was excellent: 12.5-1250ng/mL urine for HMA, HMMA, MDA and MDMA, 25-2500ng/mL for HHMA, and 150-7500ng/mL for HHA (r(2)>0.993 for all analytes). The lower limits of quantification were 12.5ng/mL urine for MDMA, MDA, HMA and HMMA, 25ng/mL for HHMA and 150ng/mL for HHA. Reproducibility was good (intra-assay precision=1.7-6.1%; inter-assay precision=0.6-5.7%), as was accuracy (intra-assay deviation=0.1-4.8%; inter-assay deviation=0.7-7.9%). Average recoveries were around 85.0%, except for HHMA (66.2%) and HHA (53.0%) (CV<8.3%). We also checked the stability of stock solutions and the internal standards after freeze-thawing and in the autosampler. Lastly, we measured the MDMA, MDA, HHMA, HHA, HMMA and HMA in urine samples taken over 24h from rats given subcutaneous MDMA.

Population pharmacokinetics of 3,4-methylenedioxymethamphetamine and main metabolites in rats.

The pharmacokinetics of the recreational drug 3,4-methylenedioxymethamphetamine (MDMA) and its mains metabolites have never been modeled together. We therefore designed a model with which to analyze the pharmacokinetics of MDMA, 3,4-methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxymethamphetamine (HMMA), and 4-hydroxy-3-methoxyamphetamine (HMA) and to test the effect of covariates like gender and body weight on the pharmacokinetics. Rats (18 males and 18 females) were given 1 mg/kg MDMA iv, and the concentrations of MDMA, MDA, and HMMA were measured by high-performance liquid chromatography-mass spectrometry. Another 30 rats (15 males) were given 1 mg/kg MDA, and MDA and HMA were measured. A population pharmacokinetic model was developed to describe the changes in MDMA, HMMA, MDA, and HMA concentrations over time and to estimate interanimal variability. The influence of gender was tested using a likelihood ratio test. Estimated exposures of males and females to MDMA and its metabolites were compared using the Wilcoxon nonparametric test. An integrated six-compartment model adequately described the data. MDMA (two compartments) was transformed irreversible to HMMA (one compartment) and MDA (two compartments), which then produced HMA (one compartment). All rate constants were first order. Females given MDMA had significantly smaller MDMA distribution volumes than males, and they converted less MDMA to MDA than did males. Our MDMA, MDA, HMA, and HMMA model is suitable for examining the relationship between drug concentrations and its pharmacological/toxicological effects. Male rats were exposed to significantly more MDA and HMA than were females, which could explain why males are more sensitive to MDMA toxic effects than females.

Sprague-Dawley rats display metabolism-mediated sex differences in the acute toxicity of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy).

The use of the amphetamine derivative 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) has been associated with unexplained deaths. Male humans and rodents are more sensitive to acute toxicity than are females, including a potentially lethal hyperthermia. MDMA is highly metabolized to five main metabolites, by the enzymes CYP1A2 and CYP2D. The major metabolite in rats, 3,4-methylenedioxyamphetamine (MDA), also causes hyperthermia. We postulated that the reported sex difference in rats is due to a sexual dimorphism(s). We therefore determined (1) the LD50 of MDMA and MDA, (2) their hyperthermic effects, (3) the activities of liver CYP1A2 and CYP2D, (4) the liver microsomal metabolism of MDMA and MDA, (5) and the plasma concentrations of MDMA and its metabolites 3 h after giving male and female Sprague-Dawley (SD) rats MDMA (5 mg.kg(-1) sc). The LD50 of MDMA was 2.4-times lower in males than in females. MDMA induced greater hyperthermia (0.9 degrees C) in males. The plasma MDA concentration was 1.3-fold higher in males, as were CYP1A2 activity (twice) and N-demethylation to MDA (3.3-fold), but the plasma MDMA concentration (1.4-fold) and CYP2D activity (1.3-fold) were higher in females. These results suggest that male SD rats are more sensitive to MDMA acute toxicity than are females, probably because their CYP1A2 is more active, leading to higher N-demethylation and plasma MDA concentration. This metabolic pathway could be responsible for the lethality of MDMA, as the LD50 of MDA is the same in both sexes. These data strongly suggest that the toxicity of amphetamine-related drugs largely depends on metabolic differences.