Urinary MDMA, MDA, HMMA, and HMA Excretion Following Controlled MDMA Administration to Humans

Abstract

3,4-Methylenedioxymethamphetamine (MDMA), or ecstasy, is excreted as unchanged drug, 3,4-methylenedioxyamphetamine (MDA), and free and glucuronidated/sulfated 4-hydroxy-3-methoxymethamphetamine (HMMA), and 4-hydroxy-3-methoxyamphetamine (HMA) metabolites. The aim of this paper is to describe the pattern and timeframe of excretion of MDMA and its metabolites in urine. Placebo, 1.0 mg/kg, and 1.6 mg/kg oral MDMA doses were administered double-blind to healthy adult MDMA users on a monitored research unit. All urine was collected, aliquots were hydrolyzed, and analytes quantified by gas chromatography–mass spectrometry. Median C_max, T_max, ratios, first and last detection times, and detection rates were determined. Sixteen participants provided 916 urine specimens. After 1.6 mg/kg, median C_max were 21,470 (MDMA), 2229 (MDA), 20,793 (HMMA), and 876 ng/mL (HMA) at median T_max of 13.9, 23.0, 9.2 and 23.3 h. In the first 24 h, 30.2–34.3% total urinary excretion occurred. HMMA last detection exceeded MDMA’s by more than 33 h after both doses. Identification of HMMA as well as MDMA increased the ability to identify positive specimens but required hydrolysis. These MDMA, MDA, HMMA, and HMA pharmacokinetic data may be useful for interpreting workplace, drug treatment, criminal justice, and military urine drug tests. Measurement of urinary HMMA provides the longest detection of MDMA exposure yet is not included in routine monitoring procedures.

Introduction

3,4-Methylenedioxymethamphetamine (MDMA), also known as ecstasy, was first produced in Germany by Merck in 1914 (1,2). Street use of MDMA in the United States started in the late 1960s (3); therapeutic use of MDMA in conjunction with psychotherapy began in the late 1970s. MDMA produces euphoria with greater self-confidence, self-acceptance, lowered defenses, and enhanced communication, empathy, or understanding (4–10). The drug has both stimulant and hallucinogenic properties and is classified as an entactogen, a subgroup of drugs that enhance tactile responses (11).

Acute health risks include hypertension, dehydration, risk of dependency, and, uncommonly, overdose and death. Animal research indicates that MDMA is neurotoxic with demonstrated toxic effects on serotonergic neurons and memory (12,13); however, in many cases, the doses and routes of exposure differ from typical oral recreational MDMA use in humans. Thus, the debate on whether MDMA exposure in humans is neurotoxic continues.

Following oral administration, MDMA is absorbed rapidly into the bloodstream (14–20). Two metabolic pathways for MDMA in humans have been described. In the major pathway, MDMA is demethylenated by CYP2D6 to form 3,4-dihydroxymethamphetamine (HHMA) (17,21). HHMA, an unstable intermediate (17), is subsequently converted to 4-hydroxy-3-methoxymethamphetamine (HMMA) by catechol-O-methyltransferase (COMT) (19) and further metabolized to 4-hydroxy-3-methoxyamphetamine (HMA) by CYP1A2. In the minor pathway, MDMA is N-demethylated by CYP3A4 to 3,4-methylenedioxyamphetamine (MDA) with further demethylenation by CYP2D6 to form3,4-dihydroxyamphetamine (HHA). This compound is O-methylated by COMT to formHMA. These four metabolites, particularly HMMA and HMA, are known to be excreted in the urine as conjugated glucuronide and sulfate metabolites (16).

There are few controlled MDMA human administration studies with doses commonly ingested by young adults. Previous pharmacokinetic studies following controlled dosing have been limited to 72 h or less (5,14,22,23). Pizarro et al. (21) administered 100 mg MDMA to healthy volunteers and recovered 44.7% of the administered dose in urine as MDMA, MDA, HMMA, or HMA. Helmlin et al. (23) found peak concentrations of 28,100 (MDMA), 2300 (MDA), 35,100 (HMMA), and 2100 (HMA) ng/mL within 1–21.5 h after oral administration of 1.5 mg/kg MDMA. Kunsman et al. (24) reported a range of MDMA and MDA concentrations of 380–96,200 ng/mL and 150–8600 ng/mL, respectively, in 34 positive urine specimens from a random drug testing program. Fallon et al. (14) administered 40 mg MDMA orally to eight adult male volunteers and collected urine samples for 72 h. They found that the majority of excreted MDMA and metabolites was recovered in the first 24 h, but no concentrations were provided.

Pharmacokinetic data provide essential scientific information for diverse fields, from emergency medicine to treatment research. Urinary pharmacokinetic data are useful for drug treatment programs to evaluate patient abstinence to support program compliance and in federally mandated workplace drug testing to promote public safety. Current mandatory guidelines for Federal Workplace Drug Testing Programs include urinary testing for MDMA and MDA with threshold for positivity at 250 ng/mL (25).

The objective of this study was to characterize urinary MDMA pharmacokinetics after low and high dosage regimens and to extend the monitoring period after controlled MDMA administration to determine windows of urinary MDMA and metabolites detection.

Materials and Methods

Study population

The protocol was approved by the Institutional Review Board of the Intramural Research Program (IRP) of the National Institute on Drug Abuse. All participants provided written informed consent. All participants underwent a comprehensive medical and psychological evaluation as part of the screening procedure. Medical and drug use history as well as clinical and drugs of abuse laboratory tests were obtained. Sixteen participants (ages 18–27 years; 6 female, 10 male) completed either one 23-day stay or three separate shorter stays on a secure clinical research unit. Participants self-reported a history of MDMA consumption, supported by at least one documented amphetamines-positive urine or MDMA-positive hair test in the prior 90 days. Individuals were screened for urinary benzodiazepines, cocaine, amphetamines, cannabis, opiates, phencyclidine (PCP), and barbiturates. Negative urine tests were required for all drug classes except amphetamines and cannabis in order for the dosing session to proceed.

Drug administration

MDMA was synthesized by Lipomed (Cambridge, MA) under good manufacturing processes. An Investigational New Drug application was secured as well as IRB approval to conduct this controlled drug administration study. The Food and Drug Administration also required an independent analysis of the product to evaluate potential impurities and to ensure participant safety. Purity by HPLC was 99.66%.

Study design

The protocol was a double-blind, randomized, placebo-controlled clinical study. Dosing conditions were randomized and assigned by the IRP pharmacy to ensure that research staff and participants were blind to administered dose. Participants had two options for study participation while residing on the closed research unit: a single, 23-day, continuous stay encompassing all three dosing sessions or three separate stays at least one week apart and completed within one year. Separate-stay participants were re-examined at each return visit to ensure continued study eligibility. After collection of baseline measures, biologic specimens, and an electrocardiogram, participants ingested one of three oral doses: placebo, 1.0 mg/kg (low), or 1.6 mg/kg (high) MDMA. Active drug was prepared as the hydrochloride salt; placebo contained only lactose. Separate-stay participants remained on the unit for 2–7 days after each dose. Dosing sessions were separated by a minimum of one week to enable determination of MDMA and metabolite detection times.

Specimens

Urine specimens were collected prior to and after administration of each dose. Every urine void was individually collected in a polypropylene bottle ad libidum and immediately refrigerated. Total volume was measured, and aliquots of urine specimens were stored in 3.5-mL polypropylene screw-cap tubes and 30-mL polypropylene bottles at −20°C prior to analysis.

Specimen preparation

Hydrolysis and extraction of urinary MDMA, MDA, HMMA, and HMA were performed according to a previously optimized published procedure (26). Briefly, urine specimens (1 mL) were acid hydrolyzed with 100 µL of concentrated hydrochloric acid at 120°C for 40 min (27). Buffered hydrolysates (pH 6) were centrifuged and applied to preconditioned solid-phase extraction (SPE) columns (Clean Screen^® ZSDAU020 extraction columns, United Chemical Technologies, Bristol, PA). Analytes were eluted with methylene chloride/2-propanol/ammonium hydroxide (78:20:2, v/v) and eluates were acidified with 1% hydrochloric acid in methanol (v/v) prior to evaporation. Extracted residues were reconstituted in ethyl acetate and derivatized with heptafluorobutyric acid anhydride (HFAA). Derivatized extracts were concentrated by evaporation, reconstituted with heptane, and quantified by gas chromatography–mass spectrometry (GC–MS).

GC–MS

GC–MS analysis was performed with an Agilent 6890 GC interfaced to an Agilent 5973 mass selective detector operating in electron impact selected ion monitoring mode (Santa Clara, CA). The GC was equipped with an HP-35 capillary column (15 m × 0.32-mm i.d. × 0.25-µm film thickness, Agilent). Quantification was performed with MDMA-d₅ and MDA-d₅ as internal standards. MDA-d₅ was employed as internal standard for HMA, MDA, and HMMA. Three ions for each analyte and two for each deuterated internal standard were monitored. The MS system was operated in selected ion monitoring mode. The ions were monitored as follows (quantitative ions in brackets): MDA-d₀ 135, [162], 375; MDA-d₅ [167], 244; MDMA-d₀ 162, 210, [254]; MDMA-d₅ 213, [258]; HMA-d₀ [240], 333, 360; and HMMA-d₀ 210, 254, [360]. The limit of quantification (LOQ) was 25 ng/mL for all analytes. Recovery and imprecision were evaluated over the method’s linear dynamic range at 30, 300, and 3000 ng/mL by assessing 10 replicates of the low, medium, and high quality control samples. Interassay recovery (% difference between mean and target concentrations) for all analytes ranged from 97.1 to 107.8%. Interassay imprecision (%RSD) at the same concentrations was between 4.0 and 10.9%.

Pharmacokinetic analyses

Concentration maxima (C_max) and times of maximum concentration (T_max) were determined for each analyte after the low and high doses. The time interval after dosing for the first specimen ≥ 25 ng/mL (LOQ) was designated as the time of first detection; the interval after dosing for the last specimen ≥ 25 ng/mL was designated as the time of last detection. Participants who had positive specimens prior to dosing (n = 3) were excluded from the determination of time of first detection for MDA (n = 1 for the low MDMA dose) and HMA (n = 2, one each for the low and high MDMA doses). The time of collection for the first positive urine specimen was not recorded for one of the 16 subjects after administration of high dose MDMA, eliminating this subject from calculations for time of onset of detection. Those participants who continued to have positive specimens at the time of discharge were excluded from the determination of the time of last detection.

The cumulative amount of analyte excreted was calculated by summing the amounts excreted in individual urine specimens (concentration times volume) from the first post-dose collection through the last urine specimen with a concentration ≥ LOQ. The percentage of total dose excreted was calculated by dividing the cumulative amount of analyte excreted by the administered dose.

Detection rates were calculated by dividing the number of positive urine specimens by the total number of specimens collected over the interval.

Comparison of differences between MDMA and HMMA median C_max was performed with Excel 2003 Data Analysis Software (Version 5.1.2600).

Results

Participant data

Six female and 10 male participants (12 African-American, 3 Caucasian, 1 unknown) received all 3 study doses and provided 916 individual urine specimens. Urinary excretion patterns over time showed substantial intersubject variability with no consistent pattern predominating; however, within an individual subject, the times of peaks and troughs for the four analytes were quite reproducible. Figure 1 displays three different representative patterns for urinary excretion of MDMA, MDA, HMMA, and HMA. Generally, HMMA exceeded MDMA concentrations, and MDA typically exceeded HMA concentrations for 30–40 h with HMA predominating later in excretion.

Figure 1.

Representative urinary MDMA, MDA, HMMA, and HMA excretion as a function of time after administration of oral MDMA. A double peak, single peak, and triple peak are shown for subjects Y, T, and GG, respectively. The change in concentration with time is shown after oral administration of 1.6 mg/kg MDMA to Subjects Y and GG and after administration of 1.0 mg/kg to Subject T.

Onset of detection and maximum urine concentrations

Table I summarizes median times (range) of first and last urine detection, C_max, and T_max for MDMA, MDA, HMMA, and HMA after controlled dosing. There appeared to be a direct correlation between dosing and median MDMA C_max, with high dose C_max increasing 1.73-fold over low dose C_max. This is comparable to the 1.6-fold increase in MDMA administration between the low and high doses. Similarly, median HMMA urine C_max increased 1.54-fold between doses. There were no significant differences between the MDMA and HMMA median C_max after the low dose, but there was a trend for higher MDMA than HMMA C_max after the high dose. MDA median C_max had a greater increase of 2.0-fold from low to high MDMA doses with C_max less than 10% of MDMA median C_max after both the low and high doses. Median HMA C_max only increased 1.2-fold despite the greater difference in MDMA dose. Median HMA C_max were 6.3 and 4.1% of the respective low and high MDMA C_max.

Table I.

Median and Range of Time of Onset of Detection^*, Urine Concentration Maximum^†, Time of Maximum Urine Concentration^‡, and Time of Last Detection^§ of MDMA, MDA, HMMA, and HMA after Low (1.0 mg/kg) and High Dose (1.6 mg/kg) Oral Administration of MDMA

		TOnset of Detection (h)			Cmax (ng/mL)		Tmax (h)		TLast Detection (h)
	Dose	N	Median	Range	Median	Range	Median	Range	N	Median	Range
MDMA	Low	16	1.34	0.83–3.33	12,376	5438–31,777	12.3	5.5–22.9	12	71.0	48.2–143.1
	High	15	1.17	0.42–1.65	21,470	12,292–48,947	13.9	3.3–30.4	11	95.5	54.6–149.5
MDA	Low	15	2.17	0.83–3.33	1116	454–3256	13.5	7.0–26.8	13	47.0	31.0–54.2
	High	15	1.63	0.92–4.50	2229	1064–5135	23.0	3.3–30.4	12	60.4	46.6–95.2
HMMA	Low	16	1.34	0.83–3.33	13,633	5698–46,876	9.9	2.1–23.3	8	104.9	69.1–142.6
	High	15	1.17	0.42–1.65	20,793	7399–36,492	9.2	3.3–30.4	9	131.1	99.3–157.8
HMA	Low	15	2.17	0.97–3.33	784	270–1716	19.8	8.3–23.8	12	61.4	48.2–104.1
	High	14	3.08	1.12–5.32	876	465–3217	23.3	11.3–30.4	11	76.3	54.6–129.4

^*T_{Onset of Detection}, n = 14–16 subjects. Participants who had positive specimens prior to dosing were excluded from determination of time of onset of detection for MDA and HMA. The time of first specimen collection was not recorded for one of the 16 subjects after administration of high dose MDMA and was not included in determining the time of onset of detection.

^†C_max, n = 16 subjects.

^‡T_max, n = 16 subjects.

^§T_{Last Detection}, n = 8–13 subjects. Participants who had positive specimens at the time of discharge were excluded from the analysis of time of last detection.

Times of maximum concentration and last detection

Intersubject T_max were highly variable for all analytes with ranges as wide as 3.3–30.4 h after a single MDMA dose (Table I). Median HMMA T_max occurred first at approximately 9.5 h with similar median times for the low and high doses. Median MDMA T_max were about 13 h after both doses. Median T_max for the lower concentration metabolites were more variable between doses, and generally occurred later at 13.5 h and 23.0 h for MDA and 19.8 h and 23.3 h for HMA following the low and high doses, respectively.

HMMA was detected longer than parent MDMA after both doses in all participants for whom a time of last detection could be determined (n = 8 for the low dose and n = 9 for high). This is reflected in a substantially longer median time of last detection for HMMA compared to MDMA (Table I and Figure 2). HMMA was detectable as long as 157.8 h (6.6 days) after high dose with a median (range) time of last detection of 131.1 h (99.3–157.8). MDMA median time of last detection was 33.9 (n = 12) and 35.6 h (n = 11) less than HMMA for low and high doses, respectively. Four and five subjects’ urine specimens were still MDMA positive at the time of discharge after the low and high doses, respectively. The times of last detection for MDA and HMA were generally shorter than for the major analytes. There were no cases where MDA was quantifiable for a longer time than MDMA, and none for HMA as compared to HMMA.

Figure 2.

Median time of last urinary detection of HMMA, MDMA, HMA, and MDA following low (1.0 mg/kg) and high (1.6 mg/kg) dose MDMA administration. The respective numbers of participants for the low and high dosing regimens for each analyte were as follows: 8 and 9 for HMMA; 12 and 11 for MDMA and HMA; and 13 and 12 for MDA.

Detection rates

Table II shows detection rates for seven days following dosing. Of the 916 specimens, 361 (39%) were positive for MDMA and/or MDA at the SAMHSA cutoff of 250 ng/mL; 96% of these were collected within 48 h of dosing. Adding HMMA substantially increased the number of positive specimens after the first 24 h. HMMA testing yielded an additional 120 positive specimens to the previously positive 361 specimens from the total of 916 over the 7-day collection period.

Table II.

Number and Percentage of Positive Specimens for MDMA, MDA, and HMMA at the Limits of Quantification^* and Proposed SAMHSA Cutoffs (n = 916)

	Time after Dose (h)	MDMA and/or MDA ≥ LOQ	MDMA and/or MDA ≥ SAMHSA†	MDMA, MDA and/or HMMA ≥ LOQ	MDMA, MDA and/or HMMA ≥ SAMHSA
Day 1	0–24	220 (24.0)	215 (23.5)	220 (24.0)	218 (23.8)
Day 2	24–48	172 (18.8)	130 (14.2)	173 (18.9)	168 (18.3)
Day 3	48–72	111 (12.1)	14 (1.5)	154 (16.8)	82 (9.0)
Day 4	72–96	26 (2.8)	2 (0.2)	95 (10.4)	10 (1.1)
Day 5	96–120	14 (1.5)	0 (0.0)	66 (7.2)	2 (0.2)
Day 6	120–144	7 (0.8)	0 (0.0)	34 (3.7)	1 (0.1)
Day 7	> 144	1 (0.1)	0 (0.0)	15 (1.6)	0 (0.0)

^*LOQ = 25 ng/mL.

^†Substance Abuse and Mental Health Services Administration (250 ng/mL).

Percent of total dose excreted as MDMA, HMMA, MDA, and HMA

The percent of oral MDMA excreted in all urine specimens over different time frames and as individual analytes is shown in Table III. Most of the dose was excreted in the urine as HMMA (approximately 20%), followed by MDMA (about 15%), MDA (about 1.5%), and HMA (about 1%). A greater percentage of the MDMA dose was excreted as MDMA after the high as compared to the low dose at all intervals evaluated, whereas greater percentages of HMMA were excreted at all intervals after the low dose. Identical patterns were seen for MDA and MDMA, and for HMA and HMMA. It is important to note that different numbers of subjects are included in Table III for the different time intervals in order to include the greatest amount of data. This must be taken into account when comparing excretion percentages. The numbers of subjects changed with different time intervals because the length of time each participant stayed on the residential unit was variable. Figure 3 displays the percent MDMA dose excreted each day for four days in the nine participants who resided on the closed research unit for a minimum of 96 h after both the low and high doses. Between 30 and 34% of total MDMA urinary excretion occurred in the first 24 h with 4–6% of drug excretion from 24 to 48 h.

Table III.

Cumulative Median (Range) Percentage^* of Oral MDMA Dose Excreted in Urine as MDMA, MDA, HMMA, and HMA

Hours after Dose	Dose	N	MDMA	MDA	HMMA	HMA	All Analytes
0–12	Low	16	7.4 (1.5–14.4)	0.5 (0.1–0.8)	10.1 (2.8–26.1)	0.3 (0.1–0.6)	19.1 (4.5–37.6)
	High	16	8.6 (2.8–15.8)	0.7 (0.3–1.1)	8.4 (3.2–14.8)	0.2 (0.1–0.5)	18.7 (9.2–29.0)
0–24	Low	16	12.1 (6.0–21.1)	1.1 (0.5–1.8)	16.3 (5.4–29.4)	0.7 (0.3–1.1)	33.5 (17.5–44.6)
	High	16	13.3 (6.8–24.6)	1.3 (0.5–2.1)	12.5 (4.8–21.1)	0.5 (0.1–1.1)	28.9 (12.3–43.8)
0–48	Low	14	13.8 (6.3–23.8)	1.3 (0.6–2.1)	19.7 (7.8–35.7)	1.0 (0.4–1.8)	37.2 (19.4–54.0)
	High	14	15.9 (8.9–25.3)	1.7 (0.8–2.5)	16.5 (7.7–22.6)	0.8 (0.4–1.4)	35.2 (17.9–43.5)
0–72	Low	11	13.6 (6.3–17.5)	1.3 (0.6–2.2)	20.8 (7.9–36.4)	1.1 (0.4–1.8)	37.0 (19.6–55.0)
	High	11	16.9 (9.0–25.4)	1.7 (0.9–2.7)	17.4 (8.3–23.1)	0.8 (0.5–1.6)	36.5 (18.6–45.8)
0–96	Low	9	13.3 (6.3–17.5)	1.2 (0.6–2.2)	20.8 (7.9–36.5)	1.1 (0.4–1.7)	36.7 (19.7–55.1)
	High	11	16.9 (9.0–25.4)	1.7 (0.9–2.7)	17.6 (8.4–23.2)	0.8 (0.5–1.7)	36.8 (18.7–46.3)
0–120	Low	5	10.4 (6.3–17.5)	0.9 (0.6–2.2)	21.4 (7.9–30.8)	1.0 (0.4–1.7)	37.2 (19.7–45.9)
	High	9	17.0 (9.0–25.4)	1.6 (0.9–2.7)	18.8 (8.4–23.3)	0.8 (0.5–1.7)	36.9 (18.8–46.5)

^*Percentages are presented for up to 120 h after low (1.0 mg/kg) and high dose (1.6 mg/kg) oral administration of MDMA.

Figure 3.

Median percent of dose excreted in the urine following low (1.0 mg/kg) and high (1.6 mg/kg) doses of MDMA. Amounts of analyte excreted for the different time intervals were calculated by summing the amounts excreted in the individual urine specimens (concentration times volume). The percentage of dose excreted was calculated by dividing the amount of analyte excreted by the administered dose. All post-dose urine specimens were included in the calculation of total percent dose excreted.

Metabolite ratios

Median ratios of MDA/MDMA, HMMA/MDMA, and HMA/MDMA and the median time to reach the highest ratio are shown in Table IV. Median analyte ratios were typically similar after low and high dose MDMA. Ratios of HMMA/MDMA were usually much greater than one after both low and high doses of MDMA. In contrast, ratios for MDA/MDMA never exceeded one after either the low or high dose. The relative concentrations of metabolites to MDMA peaked later after the high dose as compared to the low dose, as shown by the later T_max for all metabolite ratios. The time to reach maximum ratios was about 15 h longer for the high dose than low dose for MDA/MDMA and HMMA/MDMA and about 9 h longer for HMA/MDMA. The median time to maximum ratios showed substantial intersubject variability, ranging from1.2 h to more than 85 h.

Table IV.

Median and Range of Ratios of Analyte Concentrations and Time (T_max) to Reach Highest Ratio After Low (1.0 mg/kg) and High Dose (1.6 mg/kg) Oral Administration of MDMA (n = 16 Subjects)

		Ratio		Tmax (h)
	Dose	Median	Range	Median	Range
MDA/MDMA	Low	0.307	0.201–0.498	38.2	4.9–70.9
	High	0.323	0.141–0.627	53.9	40.0–82.6
HMMA/MDMA	Low	9.07	0.629–18.8	36.3	1.20–59.0
	High	6.95	1.23–17.3	51.6	1.20–85.4
HMA/MDMA	Low	1.71	0.105–3.91	49.9	34.7–61.5
	High	1.43	0.151–3.95	58.4	32.9–85.4

The change in ratios over time also showed considerable intersubject variability. Figure 4 shows three different representative patterns. Generally, ratios did not change linearly with time (i.e., increases and decreases appeared to occur randomly). Similar to the urinary excretion patterns, there was little intrasubject variability (i.e., the patterns for the three different ratios within an individual subject were comparable). HMMA/MDMA ratios were > 1 except for some specimens obtained early in the time course, usually within the first 24–48 h post-dose. MDA/MDMA ratios were always < 1 regardless of the interval after dosing, and for HMA/MDMA, typically < 1 until about 50 h after dosing when HMA concentrations exceeded those of MDMA.

Figure 4.

Ratios of HMMA/MDMA, MDA/MDMA, and HMA/MDMA in urine as a function of time after administration of oral MDMA. The change in ratios with time is shown after oral administration of 1.6 mg/kg MDMA to all subjects.

Discussion

This study was the first to monitor urinary excretion of MDMA beyond 72 h after controlled administration of high and low MDMA doses. Urine specimens were collected from participants for up to seven days after dosing. Onset of detection, C_max, T_max, concentration ratios, detection rates, and time of last detection were determined for MDMA, HMMA, MDA, and HMA.

MDMA and HMMA were first detected in urine as early as 0.42 h after oral administration of high dose MDMA. Median times of first detection were shorter for all analytes after the high dose. HMMA and MDMA were detected in all first void specimens after the high dose and in 14 of 16 first void specimens after the low dose. HMA was not detected until 5.3 h in one subject after the high dose. Approximately half of the first void specimens were positive for MDA and/or HMA after either dosing regimen.

The upper limit of the C_max range was greater for HMMA (46,876 ng/mL) than for MDMA (31,777 ng/mL) after the low dose. This was reversed after high dose MDMA; the upper limits of the C_max range were 48,947 and 36,492 ng/mL for MDMA and HMMA, respectively. There was a trend for higher median MDMA than HMMA C_max after the high but not the low dose. This is consistent with the results of Kolbrich et al. (28), who reported greater concentrations of MDMA than HMMA in plasma after administration of high but not low dose MDMA. These data support the hypothesis that MDMA to HMMA metabolism may be inhibited or oversaturated after the 1.6 mg/kg dose, yielding relatively greater MDMA plasma concentrations and hence, higher urinary concentrations. Median MDMA C_max increased by a factor of 1.73 (versus the expected 1.6) between the low and high doses. The corresponding increases in median C_max for MDA, HMMA, and HMA were 2.00, 1.53, and 1.12, respectively.

Urinary excretion patterns varied widely among subjects. One important factor could be differences in urine pH. Elimination of sympathomimetic amines is pH-dependent (29,30). Beckett et al. (30) showed that the mean urinary excretion rate of amphetamine in normal men was reduced 5-fold by maintaining a urine pH of about 8.0 and increased 3.8-fold when the pH was lowered to 5.0. The mean (± standard deviation) pH for the three subjects whose analyte concentration patterns are graphed in Figure 1 ranged from 6.33 ± 0.81 to 6.84 ± 0.54.

The major proportion of total urinary excretion occurred in the first 24 h. This agrees with results reported by Fallon et al (14). We found similar percentages (37.6 and 36.7%) of the doses excreted as a combination of MDMA, HMMA, MDA, and HMA. The largest percentage was excreted as HMMA and MDMA, with combined MDA and HMA accounting for less than 3%. HMMA concentrations were consistently greater than those of MDMA inmost urine specimens, regardless of dose administered or time interval after dosing. Pizarro et al. (21) described 44.7%total urinary excretion after 100 mg oral MDMA administration to healthy volunteers.

Based on the SAMHSA cutoffs of 250 ng/mL for MDMA and MDA, urine specimens were unlikely to be positive more than 48 h after dosing. Including HMMA with a 250 ng/mL cutoff on Day 3 increased the number of positive specimens from 14 (1.5%) to 82 (9.0%).With the addition of screening for HMMA, some specimens continued to be positive through Days 5 and 6. This increase in positive specimens was due to the longer HMMA detection time. HMMA was the major urinary metabolite on Days 2–7. Adding MDA testing did not increase sensitivity after MDMA dosing, as MDA was never positive in the absence of MDMA. HMA was not as useful for testing as HMMA; there were no cases where HMA was positive and HMMA was negative.

This controlled MDMA administration study provides pharmacokinetic data on urinary disposition of MDMA and MDA, HMMA, and HMA metabolites. These urinary pharmacokinetic data may be useful for drug treatment programs in the evaluation of patient abstinence and in federally mandated workplace drug testing to promote public safety. Current mandatory guidelines for Federal Workplace Drug Testing Programs include urinary testing for MDMA and MDA. Measurement of urinary HMMA has the longest duration of detection of MDMA exposure yet is not included in routine monitoring procedures.