1-Adrenergic Receptors Contribute to the Acute Effects of 3,4-Methylenedioxymethamphetamine in Humans

ORIGINAL CONTRIBUTION

> 1-Adrenergic Receptors Contribute to the Acute Effects of 3,4-Methylenedioxymethamphetamine in Humans

Ce´dric M. Hysek, PhD,* Anja E. Fink, MD,* Linda D. Simmler, PhD,* Massimiliano Donzelli, MSc,* Eric Grouzmann, PhD,Þ and Matthias E. Liechti, MD, MAS*

locomotor activation,13Y17 the release of dopamine in the meso- > Abstract: Preclinical studies implicate a role for 1-noradrenergic limbic system,15,18,19 self-administration,20 and drug seeking.20,21 receptors in the effects of psychostimulants, including 3,4-methylendioxy- The role of >1-adrenergic receptors in the acute effects of methamphetamine (MDMA, ‘‘ecstasy’’). The present study evaluated the MDMA is unknown. A recent clinical study showed that the > > 1 effects of the 1-noradrenergic receptor antagonist doxazosin on the acute receptor antagonist doxazosin attenuated the positive subjective pharmacodynamic and pharmacokinetic response to MDMA in 16 healthy effects of cocaine in humans.12 Therefore, we assessed the effect subjects. Doxazosin (8 mg/d) or placebo was administered for 3 days of doxazosin on the acute pharmacodynamic and pharmacoki- before MDMA (125 mg) or placebo using a randomized, double-blind, netic effects of MDMA in healthy volunteers. We hypothesized placebo-controlled, 4-session, crossover design. Doxazosin reduced MDMA- that doxazosin would reduce the MDMA-induced increase in induced elevations in blood pressure, body temperature, and moderately blood pressure and positive mood effects of MDMA. attenuated positive mood but enhanced tachycardia associated with MDMA.

The results indicate that >1-adrenergic receptors contribute to the acute cardiostimulant and to a minor extent possibly also to the thermogenic and MATERIALS AND METHODS euphoric effects of MDMA in humans. Study Design Key Words: MDMA, 3,4-methylenedioxymethamphetamine, This was a double-blind, double-dummy, placebo-controlled,

norepinephrine, doxazosin, >1-adrenergic receptor randomized crossover study with 4 experiential sessions (ie, placebo- Y placebo, doxazosin-placebo, placebo-MDMA, and doxazosin- (J Clin Psychopharmacol 2013;33: 00 00) MDMA) conducted in a balanced order. The washout periods between sessions were at least 7 days. The study was conducted at the University Hospital of Basel in accordance with the Declara- ,4-Methylenedioxymethamphetamine (MDMA, ‘‘ecstasy’’) is tion of Helsinki and International Conference on Harmonization 3a popular recreational drug with entactogenic and psycho- Guidelines on Good Clinical Practice and approved by the Ethics stimulant properties. MDMA binds to presynaptic monoamine Committee of the Canton of Basel, Switzerland, and Swiss Agency transporters and releases serotonin, norepinephrine (NE), and for Therapeutic Products (Swissmedic). The use of MDMA in Y dopamine.1 3 The carrier-mediated release of both serotonin and healthy subjects was authorized by the Swiss Federal Office of NE has been shown to contribute to the psychotropic effects of Public Health. All of the subjects provided written consent before Y MDMA in humans.4 8 Norepinephrine release has been impli- participating in the study, and they were paid for their participa- cated as a mediator of the cardiostimulant and psychostimulant tion. The study was registered at ClinicalTrials.gov (NCT01386177). response to MDMA.6,9 Specifically, the selective NE transporter The reduction in the MDMA-induced increase in blood pressure inhibitor reboxetine reduced MDMA-induced increases in plasma by doxazosin was the predefined primary outcome of this trial. NE and the acute cardiovascular and psychostimulant effects of The reduction in MDMA-induced positive mood by doxazosin MDMA in healthy subjects.9 In addition, MDMA-induced in- was a prespecified secondary outcome. creases in plasma NE were also associated with increases in good drug effects and drug liking.6 These findings implicate NE as a Study Procedures mediator of the effects of MDMA and other psychostimulants.10Y12 The subjects completed a prescreening telephone interview, However, unclear is which adrenergic receptors are involved. Pre- a screening visit, 4 test sessions, and an end-of-study visit. The clinical studies indicate that >1-adrenergic receptors regulate as- test sessions were conducted in a quiet hospital research ward with pects of psychostimulant addiction, including stimulant-induced no more than 2 research subjects present per session. The mean room temperature was 23.5-C(SD,0.5-C). The subjects arrived at the study facilities at 8:00 AM on the test day. An indwelling intravenous catheter was placed in an antecubital vein for blood From the *Division of Clinical Pharmacology and Toxicology, Department of Biomedicine, University Hospital Basel, University of Basel, Basel; and sampling. MDMA (125 mg) or placebo was administered at †Biomedicine Services, University Hospital, Lausanne, Switzerland. 9:00 AM. A standardized lunch was served at noon, and the sub- Received May 30, 2012; accepted after revision December 3, 2012. jects were sent home at 3:00 PM. Reprints: Matthias E. Liechti, MD, MAS, Clinical Pharmacology and Toxicology, University Hospital Basel, Hebelstrasse 2, CH-4031 Basel, Participants Switzerland (e-mail: [email protected]). This work was supported by the Swiss National Science Foundation Sixteen healthy subjects (8 men, 8 women) with a mean age (grant 323230_126231 to M.E.L.). of 25.8 (SD, 3.3) years were recruited from the University of Basel Supplemental digital content is available for this article. Direct URL citation campus. The allocation to treatment order was performed by appears in the printed text and is provided in the HTML and PDF versions drawing from blocks of 8 different balanced drug treatment se- of this article on the journal’s Web site (www.psychopharmacology.com). Copyright * 2013 by Lippincott Williams & Wilkins quences by a pharmacist not involved in the study. Each code ISSN: 0271-0749 was stored in a sealed envelope until the termination of the study. DOI: 10.1097/JCP.0b013e3182979d32 Data from all 16 subjects were available for the final analysis. The

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Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Hysek et al Journal of Clinical Psychopharmacology & Volume 33, Number 5, October 2013 exclusion criteria included the following: (1) age younger than 30 (SD, 5) ng/mL, similar to the concentration with steady-state 18 years or older than 45 years; (2) pregnancy determined by a dosing with 4 mg.26 urine test before each test session; (3) body mass index less than 2 18.5 or more than 25 kg/m ; (4) personal or family (first-degree Pharmacodynamics relative) history of psychiatric disorders, determined by the Structured Clinical Interview for Axis I and II disorders according Vital Signs to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Vital signs were assessed repeatedly 1 hour before and 0, Edition,22 supplemented by Symptom Checklist 90YRevised23,24; 0.33, 0.66, 1, 1.5, 2, 2.5, 3, 4, 5, and 6 hours after MDMA or (5) regular use of medications; (6) chronic or acute physical ill- placebo administration. Heart rate, systolic blood pressure, and ness assessed by physical examination, electrocardiogram, stan- diastolic blood pressure were measured using an OMRON M7 dard hematology, and chemical blood analysis; (7) smoking more blood pressure monitor (OMRON Healthcare Europe, Hoofddorp, than 7 cigarettes per day; (8) a lifetime history of using illicit drugs the Netherlands) in the dominant arm after a resting time of 5 mi- more than 5 times, with the exception of cannabis; (9) illicit drug nutes. Measures were taken twice per time point with a 1-minute use within the last 2 months; and (10) illicit drug use during the interval, and the average was used for analysis. Core (tympanic) study, determined by urine tests conducted before the test sessions temperature was assessed using a GENUIS 2 ear thermometer using TRIAGE 8 (Biosite, San Diego, CA). The subjects were (Tyco Healthcare Group, Watertown, NY). asked to abstain from excessive alcohol consumption between test sessions and limit alcohol use to 1 glass on the day before each test session. All of the subjects were nonsmokers. Thirteen sub- Psychometric Scales jects had previously used cannabis. Nine subjects reported using Subjective measures were assessed using the Adjective Mood 28 9,29,30 illicit drugs, in which 3 subjects had tried ecstasy up to 2 times, Rating Scale (AMRS), visual analog scale (VAS), and5Di- 31,32 1 subject had tried amphetamine once, 1 subject had tried lysergic mensions of Altered States of Consciousness Scale (5D-ASC). Y 28 acid diethylamide once, 3 subjects had tried nitrous oxide up to The 60-item Likert scale short version of the AMRS was ad- 3 times, and 1 subject had tried nitrous oxide and methylphenidate ministered 1 hour before and 1.25, 2, 5, and 25 hours after once. Consistent with our previous studies, we include only sub- MDMA or placebo administration. The AMRS contains subjects with no or only very limited recreational drug use to produce scales for heightened mood, self-confidence, self-reported acti- drug effects that are not or less biased by previous drug experi- vation, emotional excitation, extroversion, and dreaminess. The ences. All of the subjects were phenotyped for cytochrome P450 VAS was presented as 100-mm horizontal lines marked ‘‘not at (CYP) 2D6 activity using dextromethorphan as the probe drug. all’’ on the left and ‘‘extremely’’ on the right. The VAS was ad- Thirteen extensive metabolizers, 2 intermediate metabolizers, and ministered 1 hour before and 0, 0.33, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, and 1 poor CYP2D6 metabolizer were identified in the study. The 6 hours after MDMA or placebo administration. The 5D-ASC female subjects were investigated during the follicular phase measures alterations in mood, perception, experience of self in 32 (days 2Y14) of their menstrual cycle when the reactivity to amphet- relation to the environment, and thought disorder. The 5D-ASC amines is expected to be similar to men.25 dimension ‘‘oceanic boundlessness’’ (27 items) measures dereal- ization and depersonalization associated with positive mood. The dimension ‘‘anxious ego dissolution’’ (21 items) summarizes ego Drugs and Dosing disintegration and loss of self-control, phenomena associated with TMDMA hydrochloride (Lipomed AG, Arlesheim, anxiety. The dimension ‘‘visionary restructuralization’’ (18 items) Switzerland) was prepared as gelatin capsules (100 and 25 mg of describes perceptual alterations. The dimension ‘‘auditory alter- the salt). Identical placebo (mannitol) capsules were prepared. ations’’ (16 items) subsumes auditory (pseudo) hallucinations. MDMA was administered in a single oral dose of 125 mg, cor- The dimension ‘‘vigilance reduction’’ (12 items) describes im- responding to a mean dose of 1.91 (SD, 0.39) mg/kg body weight. paired alertness and cognitive performance. The total ASC score This dose of MDMA corresponds to a typical recreational dose was determined by adding the scores of the first 3 dimensions. of ecstasy, and comparable doses of MDMA have previously been The 5D-ASC was administered 4 hours after MDMA or placebo used in similar studies. Doxazosin was selected because it reduced administration. the effects of cocaine in a clinical study12 and can be administered once daily and up-titrated with good tolerability. Doxazosin tablets Adverse Effects (4 mg; Cardura continued-release [Pfizer, Zurich, Switzerland] Adverse effects were assessed 1 hour before and 3 and and mannitol as filler) were encapsulated within opaque gelatin 24 hours after the administration of MDMA or placebo using a list capsules, and identical placebo (mannitol pill with mannitol filler) of complaints.33 The scale consists of 66 items that yield a total capsules were prepared. A first dose of 4 mg of doxazosin was adverse effects score, reliably measuring physical and general j administered 3 days before MDMA or placebo ( 64 hours) at discomfort. 5:00 PM. A second dose of 8 mg was administered 2 days before MDMA or placebo (j40 hours) at 5:00 PM. A third dose of 8 mg was administered the day before MDMA or placebo administra- Plasma Catecholamines tion (j16 hours) at 5:00 PM. The subjects were reminded by a phone Blood samples were taken 1 hour before and 1 and 2 hours call or phone text message to ingest the capsules, and medica- after the administration of MDMA or placebo to determine the tion containers were checked to confirm that the first 2 doses of concentration of NE and epinephrine. Peak levels of NE and epi- doxazosin were administered. The last administration was super- nephrine have previously been shown to occur after 1 to 2 hours vised by study personnel at the research facility. This adminis- following administration of MDMA.34 All of the blood samples tration schedule accounted for the long tmax of 8 to 10 hours of were collected on ice and centrifuged within 10 minutes at 4-C. the continuous-release formulation of doxazosin and reduced The plasma was then stored at j20-C until analysis. The plasma the risk of hypotension.26 Based on similar dosing regimens levels of free catecholamines (NE and epinephrine) were deter- in healthy subjects,26,27 the estimated peak plasma concentration mined by high-performance liquid chromatography with an of doxazosin at the time of the administration of MDMA was electrochemical detector as described previously.9

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Pharmacokinetics reduce the increase in self-reported activation produced by Samples of whole blood for the determination of MDMA, T MDMA as evidenced by a near-significant doxazosin Â MDMA 3,4-methylenedioxyamphetamine (MDA), and 4-hydroxy-3- interaction on AUC0Y6h (Fig. 2, Table 1). Doxazosin did not methoxymethamphetamine (HMMA) were collected into lithium alter the effects of MDMA on other mood ratings (Figs. 2 and 3, heparin monovettes 1 hour before and 0, 0.33, 0.66, 1, 1.5, 2, 2.5, Table 1) or on the 5D-ASC (Supplementary Figure S1, Supple- 3, 4, and 6 hours after MDMA or placebo administration. Plasma mental Digital Content 1, http://links.lww.com/JCP/A197). concentrations of MDMA and MDAwere determined using high- MDMA increased the total list of complaints adverse effect performance liquid chromatography coupled to tandem mass score both 3 and 24 hours after drug administration compared spectrometry as described previously.6,7 Plasma concentrations with placebo (Table 1). Doxazosin did not alter the adverse effects of HMMA were determined after enzymatic hydrolysis of the of MDMA. Frequently reported acute adverse effects of placebo- glucuronide conjugates. Deglucuronidation was performed by MDMA and doxazosin-MDMA were lack of appetite (n = 12 and adding 37 nM sodium metabisulfite, 9.25 nM EDTA, and 500 or 13, respectively), thirst (n = 10 and 11, respectively), difficulties more units of A-glucuronidase type HP 2 (Sigma G7017; Sigma- concentrating (n = 9 and 9), bruxism (n = 7 and 10, respectively), Aldrich, Buchs, Switzerland) to the plasma and incubation at and sweating (n = 6 and 5, respectively). No severe adverse effects 37-C for 16 hours. HMMA sample processing was then identical were observed. to MDMA and MDA analyses. MDMA increased levels of circulating epinephrine, and this effect was not altered by doxazosin. Both MDMA and Data Analysis doxazosin increased plasma levels of NE, and the effects were ThedatafortheplasmaconcentrationsofMDMA,MDA, additive (Table 1 and Fig. 4). and HMMA were analyzed using noncompartmental models. Pharmacokinetics Maximal plasma concentration (Cmax) and time to maximal plasma concentration (Tmax) were obtained directly from the ob- The pharmacokinetics of MDMA and its metabolites MDA served concentration-time curves. The area under the plasma time and HMMA are shown in Table 2 and Figure 5. Doxazosin did not Y curve (AUC)0Y6h was calculated using the linear trapezoidal rule. affect the Cmax,AUC0 6h,orTmax of MDMA or HMMA (Figs. 5A Plasma concentrations were determined only up to 6 hours after and C, Table 2). Doxazosin lowered plasma concentrations MDMA administration because the aim of the study was to assess of MDA, reflected by slight reductions in Cmax and AUC0Y6h potential changes in plasma levels of MDMA during the time of (Fig. 5B, Table 2). Reduced CYP2D6 activity (ie, a higher the pharmacodynamic effects of MDMA. dextromethorphan-to-dextrorphan urine concentration ratio) was as- For the repeatedly measured clinical data, peak effects (E ) sociated with a larger AUC0Y6h ofMDMAandasmallerAUC0Y6h max G j G and the area under the effect curve (AUEC)0Y6h were determined. of HMMA (Rs =0.61[P 0.01] and Rs = 0.57 [P 0.05], The Emax and AUEC0Y6h values were analyzed by 2-way general- respectively). linear-model, repeated-measures analysis of variance with the 2 drug factors MDMA (MDMA vs placebo) and doxazosin DISCUSSION (doxazosin vs placebo) using Statistica 6.0 software (StatSoft, In the present study, the >1-adrenergic receptor antagonist Tulsa, OK). Tukey post hoc comparisons were performed based doxazosin decreased the MDMA-induced increases in blood on significant main effects or interactions. Additional analyses pressure but not the elevations in heart rate. The >1 receptor an- of variance were performed with drug order as an additional factor tagonist prazosin had similarly been shown to reduce the blood to exclude carryover effects. The criterion for significance was pressure response to MDMA35 and NE36 in rats. In humans, 10-day P G 0.05. A sample-size estimation based on previous data7,9 treatment with a lower daily dose of doxazosin (4 mg) also tended showed that 8 subjects would be needed to detect a relevant change to reduce systolic blood pressure elevations induced by cocaine.12 in the primary outcome (the MDMA-induced increase in blood Altogether, the findings confirm a central role for >1-adrenergic pressure) with 80% power using a within-subjects study design. receptors in the regulation of stimulant-induced hypertension. In an echocardiography study, MDMA produced higher cardiac wall RESULTS stress, suggesting higher myocardial oxygen demand than administration of the selective A-adrenergic agonist dobutamine.37 It Pharmacodynamics was therefore suggested that MDMA may increase myocardial The pharmacodynamic effects are summarized in Table 1. oxygen consumption and the risk of cardiac complications more The AUEC values are shown only for a selection of significant than is expected from the observed changes in heart rate and outcomes. MDMA significantly increased blood pressure, heart blood pressure.37 We previously showed that the NE transporter rate, and body temperature. Doxazosin significantly decreased the inhibitor reboxetine reduced the effects of MDMA including MDMA-induced increase in blood pressure, although it had no elevations in plasma levels of NE and increases in blood pressure 9 effect on blood pressure when given alone. Doxazosin enhanced and heart rate. However, selectively blocking >1-adrenergic re- the elevation of heart rate produced by MDMA (Fig. 1, Table 1). ceptors resulted in compensatory tachycardia and enhanced heart Doxazosin also reduced the increase in body temperature fol- rate increases in response to MDMA in the present study. Oppo- lowing MDMA, reflected by a significant doxazosin Â MDMA site to the effects of doxazosin on the cardiostimulant effects interaction in the AUC0Y6h for body temperature (Fig. 1, Table 1). of MDMA, A-adrenergic receptor blockers lowered tachycardia On the AMRS, MDMA produced stimulant and positive mood but enhanced the pressure response to cocaine38 and MDMA.39 effects, including increases in heightened mood, self-confidence, However, combined >,A-adrenergic receptor blockers, such as activity, emotional excitation, extroversion, and dreaminess (Fig. 2, carvedilol and labetalol, have been shown to inhibit both the blood Table 1). MDMA also increased VAS ratings for any drug ef- pressure and heart rate response to MDMA40 and cocaine41Y43 in fect, good drug effect, drug liking, drug high, and stimulated but humans. Therefore, combined >,A-adrenergic receptor blockers not for bad drug effects (Fig. 3, Table 1). Doxazosin moderately should be used in the treatment of sympathomimetic toxicity as- reduced MDMA-induced heightened mood as evidenced by a sociated with psychostimulants. significant doxazosin Â MDMA interaction in the AUC0Y6h and a In our study, MDMA increased body temperature, consistent 7,9,30,44,45 near-significant effect in the Emax. Doxazosin also tended to with previous work. Preclinical studies indicate that

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www.psychopharmacology.com TABLE 1. Pharmacodynamic Drug Effects

Doxazosin Â Main Effect Main Effect MDMA

Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Placebo- Doxazosin- Placebo- Doxazosin- of MDMA of Doxazosin Interaction Placebo, Placebo, MDMA, MDMA, Mean T SEM Mean T SEM Mean T SEM Mean T SEM F1,15 =PG F1,15 =PG F1,15 =PG Vital signs † †‡ MAP, mm Hg Emax 90.3 T 1.4 90.5 T 1.8* 110.9 T 2.9 103.4 T 2.5 81.0 0.001 3.6 NS 4.6 0.05 † †§ AUEC0Y6h 500.9 T 6.9 500.0 T 7.7* 579.9 T 6.4 542.2 T 10.3 136.6 0.001 9.2 0.01 6.8 0.05 § † †‡ Heart rate, beats/min Emax 73.6 T 2.1 80.4 T 2.5 93.4 T 3.4 102.4 T 4.1 52.0 0.001 16.7 0.001 0.4 NS † †‡ AUEC0Y6h 398.7 T 11.1 426.6 T 10.7* 466.0 T 12.3 496.5 T 17.3 51.3 0.001 11.5 0.01 0.1 NS || Body temperature, -C $Emax 0.23 T 0.05 0.39 T 0.07 0.56 T 0.09 0.41 T 0.11 4.8 0.05 0.0 NS 3.0 NS || $AUEC0Y6h j0.52 T 0.28 0.68 T 0.36 1.00 T 0.48 0.18 T 0.63 1.0 NS 0.4 NS 6.3 0.05 AMRS † † Emotional excitation $Emax j0.5 T 0.5 j0.6 T 0.7* 5.4 T 1.2 5.3 T 1.2 34.3 0.001 0.1 NS 0.0 NS ¶ Self-reported activation $Emax 0.3 T 0.5 j0.2 T 0.3* 3.9 T 1.1 2.4 T 0.9 18.5 0.001 2.0 NS 1.2 NS § || $AUEC0Y6h j1.5 T 1.9 j2.6 T 1.2 7.3 T 3.4 1.1 T 2.5 6.6 0.05 2.3 NS 4.0 0.06

† ¶ Psychopharmacology Clinical of Journal Heightened mood $Emax 0.1 T 0.4 0.3 T 0.4* 4.0 T 0.7 2.4 T 0.5 20.9 0.001 5.4 0.05 4.3 0.06 § † ‡ $AUEC0Y6h j3.3 T 2.1 j2.7 T 1.9 9.1 T 2.8 1.3 T 2.4 9.1 0.01 5.9 0.05 5.2 0.05 † ¶ Extroversion $Emax 0.0 T 0.4 0.2 T 0.5* 4.3 T 0.9 3.3 T 0.8 24.7 0.001 0.8 NS 1.2 NS § ¶ || Self-confidence $Emax j0.3 T 0.4 j0.4 T 0.4 2.1 T 0.6 1.8 T 0.7 17.7 0.001 0.3 NS 0.1 NS † † Dreaminess $Emax j0.1 T 0.2 0.3 T 0.3* 3.9 T 0.7 3.8 T 0.6 32.5 0.001 0.1 NS 0.5 NS VAS † † Any drug effect $Emax 6.8 T 5.5 8.9 T 3.7* 82.7 T 4.8 82.6 T 4.5 283.8 0.001 0.0 NS 0.1 NS † † Good drug effect $Emax 7.7 T 5.7 5.2 T 2.5* 86.8 T 4.0 85.3 T 4.3 321.5 0.001 0.2 NS 0.0 NS Bad drug effect $Emax 0.0 T 0.0 2.0 T 1.4 15.8 T 6.8 14.3 T 6.0 10.7 0.01 0.0 NS 0.1 NS † † Drug liking $Emax 7.3 T 5.7 7.8 T 3.8* 86.8 T 3.9 85.8 T 4.6 269.7 0.001 0.0 NS 0.1 NS † † Drug high $Emax 5.8 T 5.6 3.1 T 1.8* 83.9 T 4.5 82.6 T 4.7 320.3 0.001 0.2 NS 0.0 NS † † Stimulated $Emax 6.7 T 5.6 1.8 T 1.3* 73.2 T 7.8 80.3 T 5.5 130.1 0.001 0.0 NS 3.4 NS List of complaints Acute adverse effects 3h 1.3 T 0.4 2.9 T 0.7* 8.4 T 1.3† 9.2 T 1.2† 45.4 0.001 3.8 NS 0.5 NS & Subacute adverse effects 24h 0.7 T 0.3 1.9 T 0.6§ 6.5 T 1.6† 6.6 T 1.2† 17.5 0.001 1.6 NS 0.5 NS oue3,Nme ,Otbr2013 October 5, Number 33, Volume Circulating catecholamines * T T T † T † 03Lpict ilas&Wilkins & Williams Lippincott 2013 Epinephrine, nmol/L Emax 0.13 0.02 0.15 0.02* 0.39 0.04 0.50 0.07 45.3 0.001 3.1 NS 1.6 NS †§ † Norepinephrine, nmol/L Emax 1.66 T 0.20 3.56 T 0.40 2.17 T 0.14 4.40 T 0.45 * 5.1 0.05 43.3 0.001 0.4 NS The data are expressed as mean T SEM (n = 16). *P G 0.001, compared with placebo-MDMA. †P G 0.001, compared with placebo-placebo. ‡P G 0.05, compared with placebo-MDMA. MAP, mean arterial pressure. §P G 0.01, compared with placebo-MDMA. MAP, mean arterial pressure. ||P G 0.05, compared with placebo-placebo. ¶P G 0.01, compared with placebo-placebo. MAP indicates mean arterial pressure; NS, not significant. Journal of Clinical Psychopharmacology & Volume 33, Number 5, October 2013 Doxazosin and MDMA

with MDMA. These findings may indicate a possible role for >1- adrenergic receptors in the mediation of the mood-enhancing and stimulant effects of MDMA in humans and extend our previous findings of the role for NE in the psychostimulant effects of MDMA.7,9 Similarly, doxazosin has been shown to reduce the subjective liking of the acute effects of cocaine and associated feelings of being stimulated.12 Interestingly, doxazosin reduced only the effects of a low dose of cocaine; the effects of higher doses of cocaine were not significantly altered by doxazosin.12 We used only 1 relatively high dose of MDMA in the present study, and most of the mood effects of MDMA, including drug liking and feelings of being stimulated, were only nonsignificantly lowered by doxazosin. Doxazosin may therefore have had a stronger effect on the subjective responses to lower doses of MDMA. However, it is important to note that the effect of doxazosin on the subjective effects of MDMA was weak and reached significance only in the heightened mood subscale but not in several other subscales previously shown to be sensitive.4,6,9,30,49,50 In addition, we previously showed that reboxetine, which reduces MDMA-induced release of NE, attenuated MDMA-induced drug high, stimulation, and emotional excitation,9 whereas effects of MDMA on these scale scores were not significantly affected by blocking >1-adrenergic receptors in the present study. Furthermore, pretreatment with carvedilol, which blocks both >1-andA-adrenergic receptors, did not affect the subjective effects of MDMA.40 Finally, pretreatment with 5-HT transporter inhibitors, which reduce MDMA- induced release of 5-HT, was clearly more effective than treatment with either reboxetine or doxazosin to reduce the overall mood effects of MDMA.4,9,30,49 On the other hand, blockade of sero- 51,52 52,53 toninergic 5-HT1 or 5-HT2 as well as of dopaminergic 54 D2 receptors aiming to inhibit the action of the released 5-HT or dopamine was also not very effective in reducing the subjective effects of MDMA in contrast to pretreatments that aimed at blocking the interaction of MDMA with the 5-HT4,30,49 or NE transporter9 or of both the 5-HT and NE transporters.6 Taken to- gether, these studies and the present work suggest a primary role for 5-HT in the mediation of all aspects of the subjective effects of MDMA with a possible contribution of NE and >1-adrenergic receptor stimulation to the positive and stimulant subjective effects. The present findings are also consistent with preclinical data. Prazosin blocked locomotor stimulation induced by cocaine,14 16,17 13 amphetamine, and MDMA. In addition, >1 receptor knock- out mice did not show amphetamine- or cocaine-induced locomotor activity.15 Prazosin also reduced nicotine self-administration20 and nicotine-20 and cocaine-seeking behavior21 in rats. However, >1-adrenergic blockade did not affect cocaine self-administration in FIGURE 1. Doxazosin reduced the MDMA-induced increase 55 rhesus monkeys. >1-Adrenergic receptor stimulation also en- in mean arterial blood pressure (A) but enhanced the increase in hances the effects of psychostimulants on the dopamine system,56 heart rate produced by MDMA (B). Doxazosin reduced the which is thought to mainly mediate the rewarding and reinforcing MDMA-induced elevation of body temperature (C). The data are expressed as mean T SEM (n = 16). effects of drugs of abuse. For example, the amphetamine-induced release of dopamine in the nucleus accumbens was inhibited by administration of an >1-adrenergic receptor blocker into the ventral tegmental area,19 the frontal cortex,17 or systemically.17 the MDMA-induced increase in body temperature involves both In the present study, MDMA increased the plasma concen- >1-adrenergic receptorYmediated peripheral cutaneous vasocon- trations of circulating catecholamines. Circulating plasma epi- 46 striction with impaired heat dissipation and A3 receptorYmediated nephrine levels are mainly derived from the adrenal medulla, heat generation by mitochondrial uncoupling.46,47 Consistent with whereas the entrance of NE into the plasma represents an overflow preclinical data, doxazosin only partially attenuated the MDMA- by sympathetic nerves.57,58 Circulating NE is therefore considered induced increase in body temperature in the present study, where- an indicator of sympathetic system activation. Doxazosin reduces as the combined >1-andA1,2,3-adrenergic receptor antagonist vascular resistance, resulting in an antihypertensive effect. In our carvedilol has been shown to more effectively reduce the hyper- healthy young subjects, this effect of doxazosin was offset by an thermic response to MDMA in animals48 and humans.40 increase in plasma NE concentration and a higher heart rate In the present study, doxazosin also significantly reduced compared with placebo. A similar baroreceptor-mediated re- MDMA-induced increases in heightened mood, with a nonsignifi- flexive increase in NE has previously been described following 59,60 40 cant trend toward a reduction of self-reported activation associated >1- and >1,A-adrenergic receptor blockade. Interestingly,

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FIGURE 2. Subjective drug effects on the AMRS. Doxazosin decreased MDMA-induced increases in heightened mood and tended to reduce the increase in self-confidence and activity ratings produced by MDMA. The data are expressed as mean T SEM (n = 16). the sympathomimetic drug MDMA elevated NE levels to a lower of MDA, the minor but active metabolite of MDMA. MDMA is extent than blockade of >1 receptors, an important target for NE in mostly degraded to HMMA with the involvement of CYP2D6. the organs innervated by the sympathetic nervous system. Consistently, we found that subjects with lower CYP2D6 activity Doxazosin did not affect plasma concentrations of MDMA in the dextromethorphan test exhibited higher MDMA and lower or HMMA and only slightly decreased the plasma concentration HMMA plasma levels. The metabolism of MDMA to MDA

FIGURE 3. Visual analog scale ratings of subjective drug effects. Doxazosin nonsignificantly lowered MDMA-induced increases in any drug effect, good drug effect, and drug liking. The data are expressed as mean T SEM (n = 16).

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FIGURE 4. Drug effects on circulating catecholamines. MDMA increased plasma levels of epinephrine, and this effect was not altered by doxazosin (A). MDMA alone produced a weak nonsignificant increase in plasma NE levels compared with placebo (B). Doxazosin significantly increased NE levels, and the effects with MDMA were additive (B). The data are expressed as mean T SEM (n = 16).

involves CYP3A4 and CYP2B6.61 The slightly reduced levels of MDA following doxazosin pretreatment could be explained by competitive inhibition of CYP3A4 because, according to the manufacturer, doxazosin may also be metabolized by this enzyme (Pfizer). Although MDA is an active metabolite, its concentrations in the plasma are low,6,9 and the effects of doxazosin on the response to MDMA are not explained by this pharmacokinetic interaction. The fact that doxazosin did not alter plasma levels of MDMA supports our conclusion that the interactive effects of MDMA and doxazosin represent a pharmacodynamic interaction at the >1-adrenergic receptor. Several caveats of the present study should be acknowl- edged. First, we administered only single dose levels of MDMA and doxazosin. A dose-response study was not feasible because we did not want to expose our subjects to more than 2 doses of MDMA in a crossover design. We administered moderate to high doses of both drugs. As discussed above, doxazosin may have more pronounced effects at lower MDMA doses. Second, doxazosin may poorly penetrate the blood-brain barrier.62 Although we used a higher dose of doxazosin than the one previously shown to effec- 12 tively reduce the stimulant effects of cocaine, the >1-adrenergic receptor occupancy by doxazosin in the central nervous system was too low to reduce the psychoactive effects of the high dose

TABLE 2. Pharmacokinetics of MDMA, MDA, and HMMA

Cmax, AUC0Y6, ng/mL ng/mL Tmax,h per hour MDMA Placebo-MDMA 247 T 12 2.5 T 0.3 1029 T 49 Doxazosin-MDMA 243 T 12 2.9 T 0.2 992 T 50 MDA Placebo-MDMA 14.0 T 1.4 5.7 T 0.2 51.9 T 4.6 Doxazosin-MDMA 12.3 T 1.1* 5.4 T 0.3 44.3 T 3.2† HMMA Placebo-MDMA 168 T 22 1.9 T 0.2 717 T 97 Doxazosin-MDMA 169 T 25 2.1 T 0.2 730 T 104 AUC indicates area under the plasma concentration-time curve; Cmax, maximum plasma concentration; Tmax, time to maximum plasma concentration. *P G 0.05, compared with placebo-MDMA. The data are expressed FIGURE 5. Plasma concentration time profiles for MDMA (A) and as mean T SEM (n = 16). its metabolites MDA (B) and HMMA (C). Doxazosin slightly †P G 0.01, compared with placebo-MDMA. The data are expressed reduced the exposure to MDA (B) but had no effect on plasma as mean T SEM (n = 16). MDMA (A) or HMMA (C) concentrations. The data are expressed as mean T SEM (n = 16).

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of MDMA. Another >1-adrenergic blocker, such as prazosin, may 14. Wellman P, Ho D, Cepeda-Benito A, et al. Cocaine-induced hypophagia more effectively reduce the central nervous system effects of and hyperlocomotion in rats are attenuated by prazosin. Eur J psychostimulants. Third, we did not statistically correct for mul- Pharmacol. 2002;455:117Y126. tiple comparisons introduced by the many mood measures used. 15. Drouin C, Darracq L, Trovero F, et al. alpha1b-Adrenergic receptors Thus, the role of the >1-adrenergic receptors in the mood effects control locomotor and rewarding effects of psychostimulants and of MDMA needs further study. opiates. J Neurosci. 2002;22:2873Y2884. > In conclusion, 1-adrenergic receptors contribute substan- 16. Vanderschuren LJ, Beemster P, Schoffelmeer AN. On the role of tially to the blood pressure effects and partially to the thermogenic noradrenaline in psychostimulant-induced psychomotor activity and and possibly also the subjective effects of MDMA in humans. sensitization. Psychopharmacology. 2003;169:176Y185. 17. Darracq L, Blanc G, Glowinski J, et al. Importance of the ACKNOWLEDGMENTS noradrenaline-dopamine coupling in the locomotor activating effects The authors thank C. Bla¨si and L. Baseglia for their as- of D-amphetamine. J Neurosci. 1998;18:2729Y2739. sistance in study management and also M. Arends for editorial 18. Auclair A, Cotecchia S, Glowinski J, et al. D-Amphetamine fails to assistance. increase extracellular dopamine levels in mice lacking alpha 1b-adrenergic receptors: relationship between functional and AUTHOR DISCLOSURE INFORMATION nonfunctional dopamine release. J Neurosci. 2002;22:9150Y9154. The authors declare no conflicts of interest. 19. Pan WH, Sung JC, Fuh SM. Locally application of amphetamine into the ventral tegmental area enhances dopamine release in the nucleus REFERENCES accumbens and the medial prefrontal cortex through noradrenergic 1. Rudnick G, Wall SC. The molecular mechanism of ‘‘ecstasy’’ neurotransmission. J Pharmacol Exp Ther. 1996;278:725Y731. [3,4-methylenedioxy-methamphetamine (MDMA)]: serotonin 20. Forget B, Wertheim C, Mascia P, et al. Noradrenergic alpha1 receptors transporters are targets for MDMA-induced serotonin release. as a novel target for the treatment of nicotine addiction. Proc Natl Acad Sci U S A. 1992;89:1817Y1821. Neuropsychopharmacology. 2011;35:1751Y1760.

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