ResultsNo alcohols were present in the urine, consistent with the history upon arrival at the hospital. Of the immunoassay screening tests, cannabinoids (89 ng/mL) and opiates (26,380 ng/mL) were positive; all others were negative at the cut-offs previously specified. Subsequent GC-MS confirmation testing resulted in ?9-carboxy-tetrahydrocannabinol of 44 ng/mL, codeine of 28,122 ng/mL, and morphine of 48 ng/mL. Acetaminophen and caffeine were present in the acid-neutral drug screen. Acetaminophen, determined by HPLC, was 77 µg/mL. The urine was concentrated; creatinine was 1945 mg/L (17.2 mmol/L). The GC-MS basic drug screen revealed a large 5-MeO-DIPT peak, codeine, nicotine, cotinine, acetaminophen, caffeine, and two other peaks that were assumed to be 5-MeO-DIPT metabolites. The 5-MeO-DIPT, having a retention time of 803 s, was subsequently quantified by GC-MS, and found to be 1.7 µg/mL.
A portion of the chromatogram is shown in Figure 2. The two peaks A and B, presumed to be metabolites, eluted at 703 s and 881 s, respectively. Mass spectra of 5-MeO-DIPT, peaks A and B are shown in Figure 3. The mass spectrum of 5-MeO-DIPT is a simple one, having a base peak m/z 114 amu, probably from the fragment CH
2-N-[CH(CH
3)
2]
2+ ion. Such fragmentation is typical of N terminal aliphatic amines. The [M+1]
+ ion with mass 275 amu is observed with 10% relative abundance. Peak A was presumptively identified as a metabolite 5-methoxy-N-desisopropyltryptamine (5-MeO-IPT). The mass spectrum has as base peak of 161 amu with strong ions at 72, 160 and 233 amu. The 72 amu ion is attributed to the fragment CH2-NH-CH(CH3)
2 ion. The [M+1]
+ ion with mass 233 amu is relatively strong, having a 75% relative abundance. Peak B was presumptively identified as the metabolite 5-methoxy-N,Ndiisopropyltryptamine-N'-oxide metabolite (5-MeO-DIPT-N-oxide). The base peak is 114 amu, and like the parent drug, is attributed to the CH
2-N-[CH(CH
3)
2]
2+ fragment ion. A weak, 2% abundance ion was observed at m/z 291 amu which was assigned as the [M+1]
+ ion. A second 1-µL aliquot of the urine extract was injected, and chemical ionization spectra were acquired using 5% ammonia in methane as the reagent gas. The [M+1]
+ ions for 5-MeODIPT, peak A, and peak B were raised to 60%, 100%, and 20% relative abundance, respectively. There were no significant higher mass ions than the [M+1]
+ ions in the respective CI mass spectra. The same extract was also analyzed with an HP5973 MSD (Agilent Technologies, Montréal, QC, Canada) in the EI mode.
The mass spectra were identical except that weak M+ ions replaced the [M+1]
+ ions. The tendency to sometimes form [M+1]
+ in ion traps, whereas M+ are formed in quadrupole instruments is characteristic of the two types of MS.
A method developed for the confirmation of urinary amphetamines (16) was applied to an aliquot of the urine. In this method, the amphetamines are extracted into an organic solvent; the primary and secondary amines groups are derivatized with propyl chloroformate, and the tertiary amines are left unreacted. The resultant chromatogram showed the disappearance of peak A and the appearance of a new peak at 945 s. The mass spectrum and proposed structure are shown in Figure 4. The peak A metabolite, being a secondary amine, formed the expected propylchloroformate derivative.
It is reasonable to predict N-desisopropylation to be a contending metabolic pathway leading to the production of 5-MeO-IPT and hence anticipate its appearance in the urine. By analogy, Sitaram et al. (17) have shown the Ndesmethyl metabolite, 5-methoxy-N-methyltryptamine to be a minor urinary metabolite following administered 5-methoxy-N,Ndimethyltryptamine to rats. Also, Barker et al. (18) have described the N-demethylation of deuterated N,N-dimethyltryptamine in rat brain.
The assignment of peak B as the N'-oxide metabolite is proposed on the basis of 5-methoxy-N,N-dimethyltryptamine administration to rats and the recovery of formed 5-methoxy-N,N-dimethyltryptamine-N'-oxide from their urine (17,19,20) and other tissues (17). It is also possible that peak B is 6-hydroxy-5-methoxy-N,N-diisopropyltryptamine. Although hydroxylation of indole derivatives at the 6 position has been proposed (21), there is no supporting evidence in the literature to show that this pathway plays a major role in animals or humans.
In addition, Agurell et al. (19) claim that there is negligible in-vivo 6-hydroxylation of 5-methoxy-N,N-dimethyltryptamine in the rat. The identity of both peaks A and B will remain speculative until such time as authentic 5-MeO-DIPT metabolites become available.
Oxidative deamination is the major metabolic pathway for tryptamines (17,19). If 5-MeO-DIPT followed the same pathway, then 5-MeO-IAA would be formed. Further, it is possible that 5-MeO-IAA could be O-demethylated to yield 5-HIAA as it is in the rat (19). These two compounds were extracted from acidified urine. The carboxylic acid moiety of each plus the 5-hydroxy group on 5-HIAA were ethylated and analyzed by GC-MS. Extracted ion chromatograms for ethylated 5-MeO-IAA (m/z 160), ethylated 5-HIAA (m/z 174), and ethylated tolybarb (m/z 274) are displayed in Figure 5. The concentrations of 5-MeO-IAA and 5-HIAA were 1.3 µg/mL and 3.0 µg/mL, respectively. For comparison, these two compounds were determined in urine samples from 10 healthy individuals. As anticipated, no 5-MeOIAA was detected (< 0.1 µg/mL) in any of the urine samples. However, 5-HIAA, an end product of endogenous serotonin metabolism, was present at concentrations between 1.0 and 8.9 µg/mL. Random urine concentrations are expected to be in this concentration range because the normal 24-h excretion of 5-HIAA is 1.8-6.0 mg/d (22). Because the 5-HIAA was not elevated
in the patient's urine sample, it is not possible to say if demethylation of 5-MeO-IAA to 5-HIAA is an important metabolic pathway. The pathway could still be of minor importance, as has been shown in the rat (19).
[Image not displayable]
Figure 2. Portion of GC-MS total ion chromatogram of patient urine extract.
[Image not displayable]
Figure 3. Mass spectra of the parent 5-MeO-DIPT and two other urinary compounds, presumptively identified as 5-MeO-DIPT metabolites: peak A, 5-methoxy-N-isopropyltryptamine and peak B, 5-methoxy-N,N-diisopropyltryptamine-N'-oxide.
[Image not displayable]
Figure 4. Mass spectrum and proposed structure of the propylchloroformate derivative of 5-methoxy-N-isopropyltryptamine.
[Image not displayable]
Figure 5. Extracted ion chromatograms, mass spectra, and structures for the ethylated derivatives of 5-methoxyindole acetic acid (698 s), 5-hydroxyindoleacetic acid (728 s), and the internal standard tolybarb (654 s).
DiscussionIn 1980, Shulgin and Carter (7) described the administration of 5-MeO-DIPT to 10 human subjects. Each person received a 0.1 mg oral dose which was then increased in increments of 30 to 50% in subsequent drug administrations.
Threshold subjective effects were observed with a 4-mg dose. Effective doses were between 6 and 10 mg. The peak drug effect occurred at 1 to 1.5 h after ingestion, and recovery was observed after 3 h with no residual symptoms at 6 h. Subjects reported a relaxed feeling associated with emotional enhancement. They were frequently talkative and felt their conversations to be expressive and stimulating. Shulgin and Shulgin (
later summarized the responses from an additional 10 human subjects upon administration of 6 to 12 mg of 5-MeO-DIPT. Most subjects reported auditory and visual distortions. Two indicated aphrodisiac tendencies; one experienced gastrointestinal emptying, muscle spasms, and agitation; and one indicated a synergistic effect with marijuana. In our patient, the drug lasted 3.5 h. He said he felt "weird" (apprehensive) and saw symbols (visual hallucination) as opposed to being talkative or expressive of his emotions. Possibly there was a synergistic contribution from the cannabis, which might explain his muscle paralysis. However, it is not known when the cannabis was consumed; the patient denied other drug use at the time of his admission to hospital. The lower alkyl substituted 5-methoxy tryptamines such as 5-methoxy-dimethyl-tryptamine, 5-methoxy-diethyl-tryptamine, and 5-methoxy-din- propyl-tryptamine are nearly ineffective if taken orally because they are quickly degraded by monoamine oxygenase (23).
To experience the hallucinogenic effect, these agents must be administered parenterally such as through injection, snuff, or smoking. However, 5-MeO-DIPT is different is this respect because it is effective when taken orally. The major route of 5-methoxy-N,N-dimethyltryptamine metabolism in the rat is via the oxidative deamination pathway yielding 5-MeO-IAA (19).
The branched alkyl chain of the two isopropyl substituents in 5-MeO-DIPT is thought to provide enough steric hindrance to slow the oxidative deamination metabolism (7) and hence extend the drug half life. Still, the oxidative deamination pathway cannot be overlooked. In the patient's urine sample, the concentration of 5-MeO-IAA was 1.3 µg/mL, whereas the concentration of the parent drug, 5-MeO-DIPT was 1.7 µg/mL. In addition, the N-desisopropylation, and N'-oxidation pathways are also seen to be important metabolic routes as suggested by the tentative identification of 5-MeO-IPT and 5-MeO-DIPT-N'-oxide as urinary metabolites.
AcknowledgmentWe thank Ms. S. Treacy, RCMP Crime Laboratory, Winnipeg, Manitoba, Canada for procuring the Agilent 5973 mass spectra.
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