Gas chromatographic determination of methamphetamine and its metabolite amphetamine in human plasma and urine following conversion to N-propyl derivatives

Pharmacology of R-(-)-Methamphetamine in Humans: A Systematic Review of the Literature

Methamphetamine exists as two stereoisomers: S-(+)-methamphetamine ((+)-MAMP) and R-(-)-methamphetamine ((-)-MAMP). The (+)-MAMP stereoisomer is a well-known central nervous system stimulant, available as a pharmaceutical and clandestine drug of abuse. However, the (-)-MAMP stereoisomer is less well understood despite commercial availability for over 30 years as an over-the-counter (OTC) nasal decongestant in the Vicks Vapor Inhaler (a product of Procter & Gamble). Recently, several generic versions have become available, decreasing the cost and increasing the availability of (-)-MAMP-containing nasal sprays to consumers. Despite widespread commercial availability and use in the United States, a paucity of literature exists on the pharmacology of (-)-MAMP in humans. This knowledge gap is problematic, given the difficulty in separating (-)-MAMP and (+)-MAMP isomers in laboratory assays for workplace drug testing, suspected impaired drivers, post-mortem investigations, and assessment of drug involvement in crimes. In response, this systematic review of the literature coalesces and summarizes available knowledge of (-)-MAMP pharmacology in humans. It was found that available knowledge relies heavily on urine drug and metabolite concentrations, systematic pharmacokinetics studies are lacking, and existing knowledge has been derived from a total of 99 unique participants. The impacts of highlighted gaps in the literature are discussed, focusing on forensic toxicology and law enforcement, and future research directions are suggested.

Functional characterization of N-octyl 4-methylamphetamine variants and related bivalent compounds at the dopamine and serotonin transporters using Ca2+ channels as sensors

The early characterization of ligands at the dopamine and serotonin transporters, DAT and SERT, respectively, is important for drug discovery, forensic sciences, and drug abuse research. 4-Methyl amphetamine (4-MA) is a good example of an abused drug whose overdose can be fatal. It is a potent substrate at DAT and SERT where its simplest secondary amine (N-methyl 4-MA) retains substrate activity at them. In contrast, N-n-butyl 4-MA is very weak, therefore it was categorized as inactive at these transporters. Here, N-octyl 4-MA and other related compounds were synthesized, and their activities were evaluated at DAT and SERT. To expedite this endeavor, cells expressing DAT or SERT were co-transfected with a voltage-gated Ca2+ channel and, the genetically-encoded Ca2+ sensor, GCaMP6s. Control compounds and the newly synthesized molecules were tested on these cells using an automated multi-well fluorescence plate reader; substrates and inhibitors were identified successfully at DAT and SERT. N-Octyl 4-MA and three bivalent compounds were inhibitors at these transporters. These findings were validated by measuring Ca2+-mobilization using quantitative fluorescence microscopy. The bivalent molecules were the most potent of the series and were further characterized in an uptake-inhibition assay. Compared to cocaine, they showed comparable potency inhibiting uptake at DAT and higher potency at SERT. These observations support a previous hypothesis that amphetamine-related (and, here, N-extended alkyl and) bivalent arylalkylamine molecules are active at monoamine transporters, showing potent activity as reuptake inhibitors, and implicate the involvement of a distant auxiliary binding feature to account for their actions at DAT and SERT.

Estimating the intake of abused methamphetamines using experimenter-administered deuterium labeled R-methamphetamine: selection of the R-methamphetamine dose

All addictive drugs produce tolerance and addicts compensate by increasing drug exposure. Thus, the quantity of illicit drug ingested is related to the severity of addiction. Unfortunately, there are no objective methods to estimate intake for most addictive drugs. Using experimenter-administered doses of deuterium-labeled R-methamphetamine (R-[-]-MA-d3), we have developed a method to estimate the amount of abused methamphetamine intake in addicts enrolled in clinical trials. This study assessed the pharmacokinetics, pharmacodynamics, and tolerability of single oral doses of R-MA in healthy adults to select a dose of R-MA-d3 to be used as a biomarker for estimation the amount of methamphetamine abuse. This was a five-session randomized, double-blind, placebo-controlled, balanced crossover study in eight subjects. Oral R-(-)-MA was dosed at 0 mg, 1 mg, 2.5 mg, 5 mg, or 10 mg; bioavailability was estimated by slow intravenous dosing (30 minutes) of 2.5 mg R-(-)-MA-d3 given with the 2.5 mg R-(-)-MA oral dose condition. Pharmacokinetic and pharmacodynamic measures were obtained. No serious adverse events occurred during the study and all doses of R-MA were well tolerated. Linear pharmacokinetics was observed within our oral dose range of 1 to 10 mg. Complete bioavailability and pharmacologic inactivity were found for all oral doses. These characteristics indicate the advantage of using a small oral R-(-)-MA-d3 dose as a biomarker to estimate exposure to abused methamphetamine. Based on these results, 5 mg R-(-)-MA-d3 has been selected as the biomarker dose in future studies. Preliminary findings from our study indicate that experimenter-administered oral R-(-)-MA-d3 may allow estimation of abused methamphetamine intake and exposure. Knowledge of the quantity of methamphetamine intake may allow better estimation of disease severity and treatment efficacy. Experience gained from this study also can be applied to the management of other drug dependence problems such as cocaine, cannabinoid, and opiate addiction.

A validated gas chromatographic-electron impact ionization mass spectrometric method for methamphetamine, methylenedioxymethamphetamine (MDMA), and metabolites in mouse plasma and brain

A method was developed and fully validated for simultaneous quantification of methamphetamine (MAMP), amphetamine, hydroxy-methamphetamine, methylenedioxymethamphetamine (MDMA, ecstasy), methylenedioxyamphetamine, 3-hydroxy-4-methoxy-methamphetamine, and 3-hydroxy-4-methoxy-amphetamine in 100 microL mouse plasma and 7.5mg brain. Solid phase extraction and gas chromatography-electron impact ionization mass spectrometry in selected-ion monitoring mode achieved plasma linear ranges of 10-20 to 20,000 ng/mL and 0.1-0.2 to 200 ng/mg in brain. Recoveries were greater than 91%, bias 92.3-110.4%, and imprecision less than 5.3% coefficient of variation. This method was used for measuring MAMP and MDMA and metabolites in plasma and brain during mouse neurotoxicity studies.

The clinical pharmacology of intranasal l-methamphetamine

Background

We studied the pharmacology of l-methamphetamine, the less abused isomer, when used as a nasal decongestant.

Methods

12 subjects self-administered l-methamphetamine from a nonprescription inhaler at the recommended dose (16 inhalations over 6 hours) then at 2 and 4 (32 and 64 inhalations) times this dose. In a separate session intravenous phenylephrine (200 μg) and l-methamphetamine (5 mg) were given to define alpha agonist pharmacology and bioavailability. Physiological, cardiovascular, pharmacokinetic, and subjective effects were measured.

Results

Plasma l-methamphetamine levels were often below the level of quantification so bioavailability was estimated by comparing urinary excretion of the intravenous and inhaled doses, yielding delivered dose estimates of 74.0 ± 56.1, 124.7 ± 106.6, and 268.1 ± 220.5 μg for ascending exposures (mean 4.2 ± 3.3 μg/inhalation). Physiological changes were minimal and not dose-dependent. Small decreases in stroke volume and cardiac output suggesting mild cardiodepression were seen.

Conclusion

Inhaled l-methamphetamine delivered from a non-prescription product produced minimal effects but may be a cardiodepressant.

Cation-selective exhaustive injection and sweeping MEKC for direct analysis of methamphetamine and its metabolites in urine

Direct analysis of methamphetamine, amphetamine, and p-hydroxymethamphetamine in urine was achieved by cation-selective exhaustive injection and sweeping micellar EKC. A bare fused-silica capillary (40 cm, 50 microm id) was filled with phosphate buffer (80 mM, pH 3, containing 20% ACN). Then a high-conductivity buffer (100 mM phosphate, pH 3; 6.9 kPa for 2.5 min) was injected. Samples were loaded using electrokinetic injection (10 kV, 600 s) which created long zones of cationic analytes. To enhance sensitivity by sweeping, the stacking step was performed using a phosphate buffer (50 mM, pH 3, containing 20% ACN and 100 mM SDS) at -20 kV before separation by MEKC. This method was capable of detecting the analytes at ppb levels. The calibration plots were linear (r(2) >or= 0.9948) over a range of 100-5000 ng/mL for methamphetamine, and 100-2000 ng/mL for amphetamine and p-hydroxymethamphetamine. The LODs (S/N = 3) were 20 ng/mL for methamphetamine, and 15 ng/mL for amphetamine and p-hydroxymethamphetamine. The method was applied to analysis of 14 urine samples of addicts and is suitable for screening suspected samples for forensic purposes. The results showed good agreement with fluorescence polarization immunoassay and GC-MS.

Rapid and simple method for direct determination of several amphetamines in seized tablets by GC–FID

A simple and rapid method for direct simultaneous determination of amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA) and N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MBDB) in seized tablets was developed using gas chromatography with flame ionization detection. Separation of all six underivatized amphetamines, including diphenylamine as internal standard, was performed in about 6 min, using SPB-50 capillary column. Amphetamine and methamphetamine eluted with negligible tailing while the other amphetamines had highly symmetrical peaks. Sensitivity per component on-column was in the nanogram range, and reproducibility from 2.6 to 6.6% at low concentration (2.4 microg/mL) and from 1.2 to 2.6% at high (70 microg/mL) concentration. The method has a wide linear range, from Limit of detection (LOD) to almost 200 microg/mL, thus allowing analysis of different samples across a wide range of possible concentrations of amphetamines. This simple, fast and precise method using gas chromatography--flame ionization detector (GC--FID), in conjunction with other methods (TLC, IR, HPLC), can be used for identification of amphetamines and direct determination in seized tablets, especially in laboratories with heavy workload.

Determination of free-form amphetamine in rat brain by ion-pair liquid chromatography–electrospray mass spectrometry with in vivo microdialysis

An ion-pair liquid chromatography-electrospray mass spectrometry (LC-ESI-MS) method with in vivo microdialysis for the determination of free-form amphetamine in rat brain has been developed. A microdialysis probe was surgically implanted into the striatum of the rat and artificial cerebrospinal fluid (aCSF) was used as the perfusion medium. Samples were collected and then analyzed off-line by LC-ESI-MS. A reversed phase C18 column was employed for LC separation. Trifluoroacetic acid (TFA) was added in the mobile phase (acetonitrile-water, 10:90, v/v) as an ion-pair reagent. The ion-pair process disguises the protonated amphetamine cations from the ESI-MS electric field as neutral molecules. Post-column addition of volatile organic acid was utilized to minimize TFA signal suppression effect on ESI-MS detection. More than six-fold enhancement of ESI-MS response was achieved by the post-column addition of propionic acid. Good linearity (0.01-1.00 microg/ml, r2 = 0.99) and detection limit (0.002 microg/ml) were determined. Good precision and accuracy were obtained. The applicability of this newly developed method was demonstrated by continuous monitoring of amphetamine concentrations in rat brain after a single 3.0 mg/kg i.p. administration.

Derivatization in mass spectrometry-3. Alkylation (arylation)

The review is devoted to alkylation (arylation) as a widely employed derivatization procedure for the protection of OH (carboxylic acids, phosphoric acids, sulfonic acids, alcohols, polyols, phenols, enols), SH (thiols) and NH (amines, amides) groups in order to increase volatility, to improve the chromatographic properties and, if possible, mass spectral properties of derivatives. Chemical aspects of derivatization and various alkylation (arylation) reagents and reaction procedures are described. Specific mass spectral (electron ionization, chemical ionization) features of derivatives helpful in identification, structure elucidation, profiling and quantitative determination of the above-mentioned polar compounds by coupled gas chromatography or high-performance liquid chromatography are discussed. Some common analytical applications of the procedures in organic chemistry, clinical chemistry, environmental chemistry etc. are briefly summarized.

Altering cortisol level does not change the pleasurable effects of methamphetamine in humans

Preclinical studies have linked corticosteroid secretion and levels with drug self-administration by animals. In a double-blind, cross-over study, subjective, physiological, and endocrine responses to intravenous doses of methamphetamine 0.5 mg/kg or placebo were assessed in eight methamphetamine-experienced subjects after three cortisol-modifying premedication conditions: augmenting cortisol level with oral hydrocortisone 50 mg, blocking cortisol response with the corticosteroid synthesis inhibitor metyrapone 1500 mg orally, or no premedication. Although the pharmacologic manipulations produced the expected hormonal changes, subjective response to the methamphetamine showed few differences. Diminishing cortisol response by pharmacologic blockade did not alter the pleasurable effects of methamphetamine. Hydrocortisone did increase self-reported 'bad drug effect' and decreased craving after saline placebo relative to the period following methamphetamine. Metyrapone was associated with significant premature ventricular complexes in two subjects during methamphetamine administration and may not be safe for those who use methamphetamine.

A rapid method of determining amphetamine in plasma samples using pentafluorobenzenesulfonyl chloride and electron-capture gas chromatography

INTRODUCTION

Acute administration of (+)-amphetamine has been used as a model for mania in humans since it mimics the physiological, biochemical, and cognitive effects seen in mania. A rapid and sensitive method for the determination of amphetamine in human plasma samples using gas chromatography with electron-capture detection was developed in our laboratory to follow the time course of amphetamine levels in patients receiving this drug as part of a study using amphetamine as a model for mania.

METHODS

Blood samples were taken from healthy male volunteers at 30, 60, 90, 150, 210, 240, and 480 min after administration of 25 mg of (+)-amphetamine. Plasma was isolated by centrifugation and used for the analysis. This method is a modification of the procedure described by Paetsch et al. [J. Chromatogr. 573 (1992) 313] for the determination of amphetamine in rat brain tissue. Amphetamine was derivatized under basic conditions using pentafluorobenzenesulfonyl chloride (PFBSC) prior to analysis on a gas chromatograph equipped with a capillary column and an electron-capture detector. The internal standard used was benzylamine. The structure of the amphetamine derivative was confirmed using combined gas chromatography-mass spectrometry (GC-MS).

RESULTS

The limit of detection was <1 ng/ml, and the method was linear in the 1- to 100-ng range used. Mean amphetamine levels peaked at 3.5 h after drug administration, and were 40.8 +/- 1.5 ng/ml at that time.

DISCUSSION

This procedure produces a stable derivative with excellent chromatographic properties and is both simple and reproducible.

Highly sensitive analysis of methamphetamine and amphetamine in human whole blood using headspace solid-phase microextraction and gas chromatography-mass spectrometry

A simple and highly sensitive method for analysis of derivatized methamphetamine (MA) and amphetamine (AM) in whole blood was developed using headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry electron impact ionization selected ion monitoring (GC-MS-EI-SIM). A whole blood sample, deuterated-MA (d(5)-MA), as an internal standard (IS), tri-n-propylamine and pentafluorobenzyl bromide were placed in a vial. The vial was heated and stirred at 90 degrees C for 30min. Then the extraction fiber of the SPME was exposed at 90 degrees C for 30min in the headspace of the vial while being stirred. The derivatives adsorbed on the fiber were desorbed by exposing the fiber in the injection port of a GC-MS. The calibration curves showed linearity in the range of 0.5-1000ng/g for both MA and AM. The time for analysis was about 80min per sample. In addition, this proposed method was applied to two autopsy cases where MA ingestion was suspected. In one case, MA and AM concentrations in the mixed left and right heart blood were 165 and 36.9ng/g, respectively. In the other case, MA and AM concentrations were 1.79 and 0.119 microg/g in the left heart blood, and 1.27 and 0.074 microg/g in the right heart blood, respectively.

Quantification of amphetamine plasma concentrations by gas chromatography coupled to mass spectrometry

We developed a fast and sensitive method for identification and quantification of plasma concentrations of amphetamine using gas chromatography with mass spectrometry detection (GC-MS). Amphetamine-d8 served as internal standard. The method involves a single extraction procedure and an easy treatment of the samples that allowed no losses during the evaporation process. Derivatisation of amphetamine with N-methyl-bis(trifluoroacetamide), a potent acylating agent, provides many advantages to the method compared with common derivatisation reactions usually used for amphetamines. The limits of detection and quantification following this method were 0.43 and 1.42 ng/ml, respectively. The assay has been successfully employed in the quantification of amphetamine in plasma samples from healthy volunteers at four different doses.

Determination of drugs of abuse in blood

The detection and quantitation of drugs of abuse in blood is of growing interest in forensic and clinical toxicology. With the development of highly sensitive chromatographic methods, such as high-performance liquid chromatography (HPLC) with sensitive detectors and gas chromatography-mass spectrometry (GC-MS), more and more substances can be determined in blood. This review includes methods for the determination of the most commonly occurring illicit drugs and their metabolites, which are important for the assessment of drug abuse: Methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine (MDMA), N-ethyl-3,4-methylenedioxyamphetamine (MDEA), 3,4-methylenedioxy-amphetamine (MDA), cannabinoids (delta-9-tetrahydrocannabinol, 11-hydroxy-delta-9-tetrahydrocannabinol, 11-nor-9-carboxy-delta-9-tetrahydrocannabinol), cocaine, benzoylecgonine, ecgonine methyl ester, cocaethylene and the opiates (heroin, 6-monoacetylmorphine, morphine, codeine and dihydrocodeine). A number of drugs/drug metabolites that are structurally close to these substances are included in the tables. Basic information about the biosample assayed, work-up, GC column or LC column and mobile phase, detection mode, reference data and validation data of each procedure is summarized in the tables. Examples of typical applications are presented.

Derivatization procedures for gas chromatographic-mass spectrometric determination of xenobiotics in biological samples, with special attention to drugs of abuse and doping agents

The development of low cost MS detectors in recent years has promoted an important increase in the applicability of GC-MS system to analyze for the presence of foreign substances in the human body. Drugs and toxic agents are in vivo metabolized in such a way that more polar compounds are usually formed. Derivatization of these metabolites is often an unavoidable requirement for gas chromatographic analysis. Application of derivatization methods in recent years has been relevant, especially for silylation, acylation, alkylation and the formation of cyclic or diastereomeric derivatives. Given the relevance of drug of abuse testing in modern toxicology, main derivatization procedures for opiates, cocaine, cannabis, amphetamines, benzodiazepines and LSD have been reviewed. Papers describing the analyses of drugs of abuse in matrixes other than blood, such as hair or sweat, have received special attention. Advances in derivatization for sports drug testing have been particularly relevant for anabolic steroids, diuretics and corticosteroids. Among the several methodologies applied, the formation of trimethylsilyl, perfluoroacyl or methylated derivatives have proved to be both versatile and extensively used. Further advances in derivatization for GC-MS applications in clinical and forensic toxicology will depend on the one hand on the degree of further use of GC-MS for routine applications and, on the other hand, on the alternative progress made for developments in LC-MS or CE-MS. Last but not least, the appearance of comprehensive libraries in which reference spectra for different derivatives of many drugs and their metabolites are collected will have an important impact on the expansion of derivatization in GC-MS for toxicological applications.

Determination of amphetamine, methamphetamine and amphetamine-derived designer drugs or medicaments in blood and urine

This paper reviews procedures for the determination of amphetamine, methamphetamine and amphetamine-derived designer drugs or medicaments in blood and urine. Papers published from 1991 to early 1997 were taken into consideration. Gas chromatographic and liquid chromatographic procedures with different detectors (e.g., mass spectrometer or diode array) were considered as well as the seldom used thin-layer chromatography and capillary electrophoresis. Enantioselective procedures are also discussed. A chapter deals with amphetamine-derived medicaments, e.g. anoretics, antiparkinsonians or vasodilators, which are metabolized to amphetamine or methamphetamine. Differentiation of an intake of such medicaments from amphetamine or methamphetamine intake is discussed. Basic information about the biosample assayed, internal standard, work-up, GC column or LC column and mobile phase, detection mode, reference data and validation data of each procedure is summarized in Tables. Examples of typical applications are presented.

Determination of amphetamine and methamphetamine in human hair by headspace solid-phase microextraction and gas chromatography with nitrogen-phosphorus detection

A simple and rapid method for the determination of amphetamine (AP) and methamphetamine (MA) in human hair was developed by headspace solid-phase microextraction (SPME) and gas chromatography with nitrogen-phosphorus detection (GC-NPD). The hair (1 mg) was dissolved in 0.2 ml of a 5 M sodium hydroxide solution in a tightly sealed vial by shaking at 75 degrees C for about 5 min. In order to adsorb AP and MA on the SPME fiber, 100 microm of polydimethylsiloxane fiber was exposed to the headspace of the vial, and the vial was heated at 55 degrees C for 20 min. Then the fiber was removed from the vial and inserted into the injection port of the GC-NPD system using a CBJ-17 capillary column. The compounds adsorbed on the fiber were analyzed by exposing the fiber at 220 degrees C for 30 s in the GC injection port. By using this method, AP and MA in human hair could be analyzed simply and rapidly without any interference from coexisting substances. The percentages of AP and MA extracted from human hair by the SPME method were 48 and 62%, respectively, and relative standard deviations were below 10% (n=5). The calibration curves for AP and MA were linear in the ranges of 0.4-15 and 4-160 ng/mg hair, respectively. The detection limits of AP and MA at a signal-to-noise ratio of three were 0.1 and 0.4 ng/mg hair, respectively. This method could be applied to the analysis of an abuser's hair sample.

Simultaneous determination of amphetamine and its analogs in human whole blood by gas chromatography-mass spectrometry

A sensitive and specific gas chromatography-mass spectrometry (GC-MS) method for the determination of amphetamine (AM), methamphetamine (MA), methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA) and methylenedioxyethylamphetamine (MDEA) in whole blood was designed, using the respective pentadeuterated analogs of the analytes as internal standards (I.S.). After alkalinisation of blood samples, the amphetamines were extracted using diethyl ether, derivatized with heptafluorobutyric anhydride, then purified by successive washings with deionized water and 4% NH4OH. Extraction recoveries were 85.2% for AM, 90.9% for MA, 76.5% for MDA, 84.1% for MDMA and 63.6% for MDEA. Chromatographic separation was performed on a non-polar 30 m x 0.32 mm HP 5 MS capillary column using a temperature program. Detection was carried out in the electron-impact, selected ion-monitoring mode, using three mass-to-charge ratios for each analyte and one for each I.S. Limits of detection ranged from 0.5 to 8 ng/ml and limits of quantification were 10 ng/ml for AM, MDMA and MDEA; 20 ng/ml for MA; and 50 ng/ml for MDA. The method was linear from this limit up to 1000 ng/ml for all analytes, with good intra-assay precision and good intermediate precision and accuracy over these ranges. There was no interferences from other sympathomimetic drugs such as ephedrine, norephedrine or methoxyphenamine. This method is thus suitable for clinical and forensic toxicology, as well as for doping control.

Rapid and simple determination of methamphetamine and amphetamine in blood by simultaneous extraction-derivation

A method capable of extracting and derivatizing methamphetamine (MA) and amphetamine (AM) in blood simultaneously was developed. In this method ethyl acetate, triethylamine and pentafluorobenzyl bromide were added to blood, the extraction and pentafluorobenzyl derivatization of MA and AM were performed simultaneously by heating and stirring on a hot place stirrer. Pentafluorobenzyl derivatives were determined by gas chromatography/chemical ionization-mass spectrometry (GC/CI-MS). Deuterium labeled MA and AM were used as internal standards. This method enabled an accurate and precise quantitative analysis from blood containing MA and AM. Excellent results were obtained for autopsy cases with possible MA.

Methamphetamine and ethanol interactions in humans

OBJECTIVE

Methamphetamine and ethanol are commonly used together. We examined the effects of intravenous methamphetamine (30 mg), oral ethanol (1 gm/kg), and the combination of methamphetamine (30 mg) and ethanol (1 gm/kg).

METHODS

Eight methamphetamine and ethanol users were studied in a double-blind, double-placebo, within-subject, balanced Latin-square design. Ethanol was administered in six drinks over 30 minutes. Methamphetamine was injected 60 minutes after the first drink was begun. Cardiovascular, subjective, and neuropsychologic effects of the drug combinations were measured for 6 hours. Methamphetamine and amphetamine in plasma and urine were measured by capillary gas chromatography for 48 hours. Data were analyzed by repeated-measures ANOVA.

RESULTS

Compared with methamphetamine alone, the combination increased heart rate but decreased systolic blood pressure. The net cardiovascular effect was an increase in rate pressure product, an index of cardiac work and myocardial oxygen consumption. The combination diminished the subjective effects of ethanol while not affecting the subjective effects of methamphetamine. Methamphetamine pharmacokinetics were not altered by the concurrent administration of ethanol, with the exception of lowering the apparent volume of distribution at steady state for methamphetamine.

CONCLUSIONS

As a potent sympathomimetic drug with alpha-agonist-like effects, methamphetamine increased systolic blood pressure, with minimal change in heart rate. The concurrent administration of methamphetamine and ethanol increased cardiac work, which could produce more adverse cardiovascular effects than either drug taken alone. The increased perceived global intoxication may explain the popularity of this drug combination.