Detection and time course of cocaine N-oxide and other cocaine metabolites in human plasma by liquid chromatography/tandem mass spectrometry.

Gas chromatography/mass spectrometry (GC/MS) is often used for detection and measurement of cocaine metabolites in biological specimens. However, cocaine N-oxide, a recently identified metabolite of cocaine, is thermally degraded when introduced into a GC/MS. The major degradation products are cocaine and norcocaine.

Analysis of fentanyl and norfentanyl in human plasma by liquid chromatography-tandem mass spectrometry using electrospray ionization.

This report describes a sensitive and specific high-performance liquid chromatography (HPLC)-electrospray ionization-tandem mass spectrometry (MS-MS) method for the detection of subnanogram concentrations of fentanyl and its metabolite norfentanyl in human plasma. The assay was based on a liquid-liquid extraction of 0.5 mL of human plasma, with a lower limit of quantitation (LLOQ) of 0.

Stability of plasma gamma-hydroxybutyrate determined by gas chromatography-positive ion chemical ionization-mass spectrometry.

An effective method for the determination of gamma-hydroxybutyric acid (GHB) in human plasma is described that utilizes a simple liquid-liquid extraction procedure and gas chromatography-positive ion chemical ionization-mass spectrometry (GC-PCI-MS). The method has been used to study the stability of plasma GHB under several storage conditions. Following the extraction with acetonitrile, GHB and deuterated GHB (GHB-d(6)) were derivatized with N,O-bis[trimethylsilyl] trifluoroacetamide (BSFTA).

A liquid chromatographic-tandem mass spectrometric method for the analysis of serotonin and related indoles in human whole blood.

This paper describes a high-performance liquid chromatographic-tandem mass spectrometric (HPLC-MS-MS) method for the determination of serotonin (5-HT) and the related indoles tryptophan (TRP), 5-hydroxyindoleacetic acid (5-HIAA), indole-3-acetic acid (IAA), and indole-3-proprionic acid (IPA) in whole blood. Ionization was achieved by atmospheric pressure chemical ionization (APCI). The method uses a solvent gradient to achieve baseline separation of all analytes.

Ofloxacin as a reference marker in hair of various colors.

It has been proposed that administration of a reliable marker substance to human subjects may enhance the ability to identify drug use and treatment compliance in drug treatment programs. The goal of this study was to determine if an oral dose of the antibiotic ofloxacin (OFLX) could be used as a "marker" substance to establish reference points with respect to time in hair of various colors. Male and female subjects (n = 32) between 18 and 40 years of age received 800 mg of OFLX as a divided oral dose on a single day.

Metabolism of capsaicin by cytochrome P450 produces novel dehydrogenated metabolites and decreases cytotoxicity to lung and liver cells.

Capsaicin is a common dietary constituent and a popular homeopathic treatment for chronic pain. Exposure to capsaicin has been shown to cause various dose-dependent acute physiological responses including the sensation of burning and pain, respiratory depression, and death. In this study, the P450-dependent metabolism of capsaicin by recombinant P450 enzymes and hepatic and lung microsomes from various species, including humans, was determined.

Determination of l-alpha-acetylmethadol (LAAM), norLAAM, and dinorLAAM in clinical and in vitro samples using liquid chromatography with electrospray ionization and tandem mass spectrometry.

l-Alpha-acetylmethadol (LAAM) is an alternative to methadone for the maintenance treatment of opioid dependence. LAAM has a longer therapeutic half-life than methadone, primarily because it is metabolized to more active metabolites, norLAAM and dinorLAAM. We have developed a liquid chromatography-tandem mass spectrometry method capable of measuring LAAM and its metabolites, norLAAM and dinorLAAM, at lower concentrations with 1.

A field evaluation of five on-site drug-testing devices.

A field study was performed at two police agencies to evaluate the utility and accuracy of five on-site urine analysis drug-testing devices when used to test driving under the influence (DUI) arrestees. The devices evaluated were AccuSign, Rapid Drug Screen, TesTcup-5, TesTstik, and Triage. Standard workplace screening cut-off concentrations were used and samples were tested for marijuana, cocaine and metabolites, amphetamine(s), opiates, and PCP (except opiates 300 ng/mL).

Determination of capsaicin, nonivamide, and dihydrocapsaicin in blood and tissue by liquid chromatography-tandem mass spectrometry.

A sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS-MS) method for the analysis of capsaicin, nonivamide, and dihydrocapsaicin in blood and tissue has been developed. The method utilized a one-step liquid-liquid extraction that yielded an approximate 90% recovery of capsaicinoids from blood. Chomatographic separation of the capsaicinoids was achieved using a reversed-phase high-performance liquid chromatography column and a stepwise gradient of methanol and distilled water containing 0.

A liquid chromatographic-electrospray ionization-tandem mass spectrometric method for determination of buprenorphine, its metabolite, norbuprenorphine, and a coformulant, naloxone, that is suitable for in vivo and in vitro metabolism studies.

A liquid chromatographic-electrospray ionization-tandem mass spectrometric method has been developed and validated for determination of the antiabuse medication, buprenorphine, its primary metabolite, norbuprenorphine, and a proposed coformulant, naloxone. The method uses deuterated internal standards and a simple liquid-liquid extraction. Mass spectrometry employed selected reaction monitoring of the transitions of m/z 468 to 396 for buprenorphine, 472 to 400 for [2H4]buprenorphine, 414 to 101 for norbuprenorphine, 423 to 110 for [2H9]norbuprenorphine, 328 to 310 for naloxone, and 345 to 327 for its internal standard, [2H3]naltrexone.

Simultaneous determination of delta9-tetrahydrocannabinol and 11-nor-9-carboxy-delta9-tetrahydrocannabinol in human plasma by solid-phase extraction and gas chromatography-negative ion chemical ionization-mass spectrometry.

Delta9-tetrahydrocannabinol (THC) and 11-nor-9-carboxy-delta9-tetrahydrocannabinol (THCA) in human plasma can be simultaneously detected using solid-phase extraction with gas chromatography and negative ion chemical ionization mass spectrometry. THC-d3 and THCA-d3 are added as internal standards; protein is precipitated with acetonitrile and the resulting supernatants diluted with 0.1 M sodium acetate (pH 7.

A validated liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry method for quantitation of cocaine and benzoylecgonine in human plasma.

In order to support studies on various medication protocols for the treatment of cocaine abuse, an accurate, precise, and sensitive (2.5 to 750 ng/mL) liquid chromatography-tandem mass spectrometry assay was developed to determine cocaine and benzoylecgonine in human plasma. Cocaine-d3 and benzoylecgonine-d3 were added as internal standards and samples were subjected to solid-phase extraction.

Differential N-demethylation of l-alpha-acetylmethadol (LAAM) and norLAAM by cytochrome P450s 2B6, 2C18, and 3A4.

Incubation of l-alpha-acetylmethadol (LAAM) or norLAAM with cDNA-expressed P450s 3A4, 2B6, and 2C18 produced significant N-demethylation products. P450s 2C19, 2C8, 3A5, 2C9, 3A7, 1A1, and 2D6 (norLAAM only), also produced detectable product. Coexpression of cytochrome b(5) enhanced LAAM N-demethylation, most dramatically for 3A4, but had marginal effects on norLAAM N-demethylation.

Quantitative analysis of capsaicinoids in fresh peppers, oleoresin capsicum and pepper spray products.

Liquid chromatography-mass spectrometry was used to identify and quantify the predominant capsaicinoid analogues in extracts of fresh peppers, in oleoresin capsicum, and pepper sprays. The concentration of capsaicinoids in fresh peppers was variable. Variability was dependent upon the relative pungency of the pepper type and geographical origin of the pepper.

The ATPase reaction cycle of yeast DNA topoisomerase II. Slow rates of ATP resynthesis and P(i) release.

DNA topoisomerase II catalyzes the transport of one DNA duplex through a transient break in a second duplex using a complex ATP hydrolysis mechanism. Two key rates in the ATPase mechanism, ATP resynthesis and phosphate release, were investigated using 18O exchange and stopped-flow phosphate release experiments, respectively. The 18O exchange results showed that the rate of ATP resynthesis on the topoisomerase II active site was slow compared with the rate of phosphate release.

Determination of capsaicin, dihydrocapsaicin, and nonivamide in self-defense weapons by liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry.

Sensitive and selective liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS) methods for the analysis of capsaicin, dihydrocapsaicin, and nonivamide in pepper spray products have been developed. Chromatographic separation of the capsaicinoid analogues was achieved using a reversed-phase HPLC column and a stepwise gradient of methanol and distilled water containing 0.1% (v/v) formic acid.

Evaluation of immunoassays for semiquantitative detection of cocaine and metabolites or heroin and metabolites in extracts of sweat patches.

Two types of immunoassays, radioimmunoassay (RIA) and microplate enzyme immunoassay (EIA), were compared for their ability to detect and quantitate cocaine and metabolites or heroin and metabolites in extracts of sweat patches. Experiments used sweat patches that had been fortified with cocaine, benzoylecgonine (BE), and ecgonine methyl ester (EME) or 6-acetylmorphine (6-AM), heroin, and morphine. Assays were first evaluated for sensitivity in detection of the analyte(s) known to be excreted in sweat (cocaine >> BE and EME; 6-AM > heroin > morphine).

Variables in human liver microsome preparation: impact on the kinetics of l-alpha-acetylmethadol (LAAM) n-demethylation and dextromethorphan O-demethylation.

We examined three primary variables in the preparation of human liver microsomes. In three experiments, each using three livers, we manipulated 1) the force of the first centrifugation (9,000, 10,500, or 12,000g); 2) the presence of sucrose in the homogenization buffer; and 3) the number of homogenizing strokes (6, 8, or 10). Sedimentation plots for the marker enzymes succinate dehydrogenase, NADPH cytochrome P450 reductase (reductase), and glutathione S-transferase in the resulting premicrosomal, microsomal, and cytosolic fractions suggest that enhanced purity of microsomes can be obtained by reducing force of centrifugation, including sucrose, and increasing the number of homogenization strokes.

The incorporation of cocaine and metabolites into hair: effects of dose and hair pigmentation.

The relationship between xenobiotic concentrations in hair and the degree of systemic xenobiotic exposure is poorly defined. The purpose of this study was to evaluate the effect of dose, time, and pigment on the hair incorporation of cocaine (COC) and its metabolites, benzoylecgonine (BE), ecgonine methyl ester (EME), and norcocaine (NCOC). COC was administered by the i.

Urinary excretion of 4-hydroxyamphetamine and amphetamine in male and female Sprague-Dawley and Dark Agouti rats following multiple doses of amphetamine.

Previous studies have demonstrated that the cytochrome P450 2D subfamily is involved in the 4-hydroxylation of amphetamine in the rat. These studies followed urinary levels of 4-hydroxyamphetamine and amphetamine after a single dose of amphetamine given with the P450 2D inhibitor quinidine or in P450 2D-deficient Dark Agouti (DA) rats. Multiple doses of amphetamine are used by humans and in experimental neurotoxicity studies of amphetamine.

The effects of collection methods on oral fluid codeine concentrations.

The use of a variety of alternative biological specimens such as oral fluid for the detection and quantitation of drugs has recently been the focus of considerable scientific research and evaluation. A disadvantage of drug testing using alternative specimens is the lack of scientific literature describing the collection and analyses of these specimens and the limited literature about the pharmacokinetics and disposition of drugs in the specimen. Common methods of oral fluid collection are spitting, draining, suction, and collection on various types of absorbent swabs.

Validation of twelve chemical spot tests for the detection of drugs of abuse.

Validation procedures are described for 12 chemical spot tests including cobalt thiocyanate, Dille-Koppanyi, Duquenois-Levine, Mandelin, Marquis, nitric acid, para-dimethylaminobenzaldehyde, ferric chloride, Froehde, Mecke, Zwikker and Simon's (nitroprusside). The validation procedures include specificity and limit of detection. Depending on the specificity of each color test, between 28 to 45 drugs or chemicals were tested in triplicate with each of the 12 chemical spot tests.

Selective involvement of cytochrome P450 2D subfamily in in vivo 4-hydroxylation of amphetamine in rat.

The cytochrome P450 (P450) 2D subfamily catalyzes ring hydroxylation of amphetamines. We tested the hypothesis that P450 2D is selectively involved in amphetamine 4-hydroxylation. Urinary elimination of 4-hydroxyamphetamine and amphetamine was determined in male Sprague-Dawley rats pretreated with P450 inducers and inhibitors.