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W D Darwin

Publications and source records attributed to W D Darwin.

At least 37 records · Page 2Linked to original sources
PubMed1993

Measurement of heroin and its metabolites by isotope-dilution electron-impact mass spectrometry.

A solid-phase extraction procedure was developed for the isolation of heroin, 6-acetylmorphine, and morphine from blood, plasma, saliva, and urine with subsequent assay by gas chromatography/mass spectrometry. Aprotic solvents, mild elution conditions, and an enzyme inhibitor were used to ensure maximum analyte stability. Samples were extracted and the extract was divided into two equal portions. One portion was assayed directly for heroin; detector response was linear over a concentration range of 1.0 to 250 micrograms/L. The second part of the extract was reacted with N-methyl-bis-trifluoroacetamide and assayed for the trifluoroacetyl derivatives of 6-acetylmorphine and morphine; detector response was linear over a concentration range of 1.0 to 500 micrograms/L. The limit of sensitivity was 1.0 microgram/L for each analyte. Hydrolysis of heroin to 6-acetylmorphine during extraction and analysis was < 5%. The method can be used to corroborate heroin use and to study the pharmacological effects of heroin and its metabolites.

Body Fluids↗
PubMed1992

Rapid assay of cocaine, opiates and metabolites by gas chromatography-mass spectrometry.

The simultaneous assay of cocaine, opiates and metabolites in small biological samples continues to be a difficult task. This report focuses upon tabulation of important techniques (extraction, derivatization, chromatographic conditions, detection mode, data acquisition) reported over the last decade that were used in the development of assays for these analytes. The most prevalent procedures for extraction of cocaine, opiates and metabolites were liquid-liquid and solid-phase extraction isolation methods. Following extraction analytes were derivatized and analyzed by gas chromatography-mass spectrometry. The technique most often used for chromatographic separation was fused-silica capillary column gas chromatography. Detection generally was performed by selected ion monitoring in the positive-ion electron-impact ionization mode, although full-scan acquisition and positive- and negative-ion chemical ionization methods have been used. It was apparent from the review that there is a continuing need for greater sensitivity and selectivity in the assay of highly potent opiates and for cocaine and metabolites.

Cocaine↗
PubMed1986

Diazepam and methadone blood levels following concurrent administration of diazepam and methadone.

Results of a previous study indicated that the opioid effects of methadone were enhanced by the concurrent administration of diazepam in methadone-maintained subjects. To determine whether a pharmacokinetic interaction might account for this methadone-diazepam interaction, the plasma levels of methadone, diazepam and diazepam metabolites were determined in blood samples collected during that study. Five adult male patients on methadone maintenance (50-60 mg/day) were administrated single doses of placebo, diazepam (20 and 40 mg), methadone (100%, 150% and 200% of the maintenance dose), and four diazepam-methadone dose combinations (20 and 40 mg diazepam in combination with 100% and 150% of the maintenance dose). The results showed that the concurrent administration of methadone and diazepam did not significantly change the time-course or areas under the plasma concentration-time curve of methadone, diazepam or N-desmethyl-diazepam compared to the levels following the administration of either drug alone. Thus, plasma drug level analysis does not indicate a pharmacokinetic interaction between diazepam and methadone.

Adult↗
PubMed1985

63Ni electron-capture gas chromatographic assay for buprenorphine and metabolites in human urine and feces.

A 63Ni electron-capture gas chromatographic assay is described for buprenorphine, a potent narcotic agonist--antagonist. In addition, the assay is useful for the measurement of the metabolite norbuprenorphine and demethoxybuprenorphine, a rearrangement product resulting when buprenorphine is exposed to acid and heat. An extraction procedure was developed which optimized recovery of buprenorphine from biological samples and produced minimal background interferences and emulsion problems. Extract residues were derivatized with pentafluoropropionic anhydride and assayed by gas chromatography. Samples were analyzed with and without enzyme hydrolysis, thus providing a selective and sensitive assay for both free and conjugated buprenorphine, norbuprenorphine and demethoxybuprenorphine. The lower limits of detection following extraction of a 1-ml sample were ca. 10 ng/ml for buprenorphine and demethoxybuprenorphine and 5 ng/ml for norbuprenorphine. Application of the assay to human samples following a 40-mg oral dose of buprenorphine produced no evidence for the presence of demethoxybuprenorphine in urine or feces. Norbuprenorphine (free and conjugated) was present in urinary and fecal samples; buprenorphine (free and conjugated) was found in high amounts only in feces and in trace amounts in urine as conjugated buprenorphine. The urinary and fecal excretion pattern observed for a human subject following oral dosing of buprenorphine suggests enterohepatic circulation of buprenorphine.

Adult↗
PubMed1984

Stability of the 6,14-endo-ethanotetrahydrooripavine analgesics: acid-catalyzed rearrangement of buprenorphine.

Buprenorphine (I), a member of the 6,14-endo-ethanotetrahydrooripavine series of analgesics, undergoes an acid-catalyzed rearrangement reaction when exposed to acid and heat. The product was shown by 1H-NMR and GC-MS to have undergone overall elimination of a molecule of methanol with concurrent formation of a tetrahydrofuran ring at C(6)-C(7) of I. Short-term stability studies across a wide range of pH and temperature conditions indicate that I is stable in aqueous solution at pH greater than 3 for 24 h at 36-38 degrees C. Under the more extreme conditions of the autoclave, significant loss of I occurred. Long-term stability studies (10 weeks) of I in aqueous solution (pH 1 and pH 5) at 0-4 degrees C and 26-28 degrees C indicate only minor conversion (4%) to the rearrangement product. Eight other 6,14-endo-ethanotetrahydrooripavine derivatives were subjected to extremes of acid (pH 0) and temperature (autoclave) to determine if similar rearrangement reactions occur. GC-MS indicated that hydrolysis products were produced whose spectra were consistent with the proposed rearrangement structures.

Analgesics↗
PubMed1983

Assay for codeine, morphine and ten potential urinary metabolites by gas chromatography--mass fragmentography.

A mass fragmentography (MF) assay is described for ten potential, minor urinary metabolites of codeine (C) and morphine (M). Samples were hydrolyzed, extracted, derivatized with Tri-Sil Z and analyzed by methane chemical ionization (CI)-MF. The method is sensitive to ca. 0.01 microgram/ml for all compounds with the exception of normorphine (NM) which was difficult to extract with chloroform. The sensitivity of the MF assay for NM was only ca. 0.10 microgram/ml. Various solvent systems were investigated for optimization of extraction efficiency of all metabolites. A separate method for the extraction of NM is reported which utilizes a solid buffer--solvent combination, i.e., potassium carbonate--isopropanol. This latter method provided the best overall recovery of NM (39.0 +/- 3.4%). Gas chromatographic (GC) retention times of C, M and metabolites are reported for three liquid phases (3%) on Gas-Chrom Q (100-120 mesh). Resolution of metabolites (as trisilyl derivatives) was best on Silar-5CP and this phase was used in metabolic studies of C and M. GC resolution was not complete for all compounds; however, selection of specific ions for monitoring by MF provided the required specificity for all compounds except the 6 alpha- and 6 beta-hydroxy isomers. CI spectra for all metabolites are reported. The MF assay was used for urinary analysis of samples from guinea pigs that received single doses of C (15 mg/kg) or M (8 mg/kg). Following C administration 6 alpha- and 6 beta-hydrocodol, 6 alpha, beta-hydromorphol (undifferentiated), HM and M were measured. Following M administration only 6 alpha, beta-hydromorphol was found. The amount of total metabolite as percent dose for each component was calculated as less than 1%.

Animals↗
PubMed1982

Detection and measurement of opium alkaloids and metabolites in urine of opium eaters by methane chemical ionization mass fragmentography.

A gas chromatographic-mass spectrometric assay for eight opium alkaloids in human urine following opium ingestion is described. The compounds were extracted from urine with methylene chloride-isopropanol (7:3, v/v) at pH 9.5, evaporated, derivatized with Tri-Sil Z and analyzed by methane chemical ionization mass fragmentography. The method in sensitive to ca. 0.01 microgram/ml for morphine and codeine and ca. 0.05 microgram/ml for the other compounds. Adsorption problems on the gas chromatography column prevented obtaining reproducible results for the measurement of noscapine. Extraction efficiencies over the pH range of 8-11 for the eight compounds are reported. Retention times of the opium alkaloids were determined using five different liquid phases (3%) on Gas-Chrom Q (100-120 mesh) and two column lengths (36 cm and 183 cm). The 36-cm column packed with OV-210 was selected for use in the assay. Ions were selected for monitoring for each component from their methane chemical ionization spectrum to provide the needed sensitivity and specificity for analysis of a multi-component mixture. The assay was used for the analysis of an "opium eater's" urine. Morphine, codeine, nomorphine, norcodeine and noscapine were detected; however, no evidence was obtained for thebaine, papaverine or oripavine. Unconjugated morphine (0.64 microgram/ml) was present at nearly twice the concentration of codeine (0.37 microgram/ml) and normorphine and norcodeine were present in equal amounts (ca. 0.15 microgram/ml).

Gas Chromatography-Mass Spectrometry↗
PubMed1980

Fluorescence properties of pseudomorphine and congeners: structure-activity relationships.

The fluorescence properties of morphine congeners oxidized with potassium ferro-ferricyanide are described. Fluorescence did not occur in congeners with the following structural features: an alkyl or acyl group at the 3-O-position, a C-6 carbonyl group, or absence of the furan oxygen. Masking the carbonyl group by ethylene ketal formation effectively restored fluorescence. Morphine congeners that fluoresced were most sensitive to structural changes at C-6, C-7, anC-8. Details of effects of structural changes on emission maxima, intensity, and Stokes' shift are reported.

Molecular Conformation↗
PubMed1979

Comparative metabolism of codeine in man, rat, dog, guinea-pig and rabbit: identification of four new metabolites.

The metabolism and excretion of codeine and its metabolites in untreated urine of man, rat, dog, guinea-pig and rabbit have been examined. Metabolites were identified by gas chromatography mass spectrometry operated in the chemical ionization mode (methane). Concentrations of codeine and metabolites were measured by selected ion monitoring. Both codeine and norcodeine were detected in the urine of all species but a new metabolite, hydrocodone, was found only in the urine from man, guinea-pig and dog. Additional metabolites (presumably resulting from the metabolism of hydrocodone) were also detected in man and guinea-pig. Overall recoveries of drug and metabolites from untreated urine were low for all species.

Adult↗
PubMed1978

Simultaneous determination of hydromorphone, hydrocodone and their 6alpha- and 6beta-hydroxy metabolites in urine using selected ion recording with methane chemical ionization.

A selected ion recording using chemical ionization (methane) is described for the simultaneous measurement of hydrocodone, hydromorphone and their respective 6alpha- and 6beta-hydroxymetabolites in human urine. The samples were acid-hydrolyzed, extracted and derivatized by silylation. Only partial resolution of the components on 3% OV-17 was achieved but was sufficient for their determination. The [M+1]+ ions of the drugs and metabolites as well as the [M+29]+ ion of the internal standard were recorded. The assay was sensitive down to c. 0.01 microgram ml-1. The relative standard deviation of standards processed along with the samples ranged from 4.5-8.2%. Hydrocodone was found to be metabolized in man primarily by O-demethylation and 6-keto reduction. Hydromorphone was excreted mainly in the unchanged form (after acid-hydrolysis) with only minor amounts of the 6-hydroxymetabolites being detected. A lack of stereoselectivity in the metabolic reduction ofhydrocodone was observed.

Codeine↗
PubMed1978

The identification and measurement of two new metabolites of naltrexone in human urine.

Two metabolites of naltrexone were identified in human and rat urine following drug administration. The metabolites, 2-hydroxy-3-0-methylnatrexone and 2-hydroxy-3-0-methyl-6 beta-naltrexol, were identified by comparison of their respective gas chromatographic retention times and methane chemical ionization spectral patterns with authentic standards. The standards were obtained by chemical synthesis from naltrexone. Urinary excretion of the two metabolites was measured by single ion recording of the pseudomolecular ions of the metabolites and an internal standard. Excretion data was collected from 5 human subjects over a period of 5 days following a single dose of naltrexone. The metabolites, 2-hydroxy-3-0-methylnatrexone and 2-hydroxy-3-0-methyl-6 beta-natrexol were found to account for an average (+/- standard error) of 0.45 +/- 0.08% and 4.6 +/- 2.1% of the administered dose, respectively. An unusually long half-life of elimination of the latter metabolite (mean of 20.2 +/- 1.8 hr) was observed. Acid-hydrolysis of the samples failed to produce a significant increase of either metabolite indicating that the major protion of these metabolites is excreted in the free form.

Animals↗
PubMedDate not supplied

Passive inhalation of marijuana smoke: urinalysis and room air levels of delta-9-tetrahydrocannabinol.

In two separate studies, 5 drug-free male volunteers with a history of marijuana use were passively exposed to the sidestream smoke of 4 and 16 marijuana cigarettes (2.8% delta-9-tetrahydrocannabinol [THC]) for 1 h each day for 6 consecutive days. A third study was similarly performed with 2 marijuana-naive subjects passively exposed to the smoke of 16 marijuana cigarettes. Passive smoke exposure was conducted in a small, unventilated room. Room air levels of THC and CO were monitored frequently. All urine specimens were collected and analyzed by EMIT d.a.u. assay, Abuscreen radioimmunoassay and GC/MS. The studies show that significant amounts of THC were absorbed by all subjects at the higher level of passive smoke exposure (eg., smoke from 16 marijuana cigarettes), resulting in urinary excretion of significant amounts of cannabinoid metabolites. However, it seems improbable that subjects would unknowingly tolerate the noxious smoke conditions produced by this exposure. At the lower level of passive marijuana-smoke exposure, specimens tested positive only infrequently or were negative. Room air levels of THC during passive smoke exposure appeared to be the most critical factor in determining whether a subject produced cannabinoid-positive urine specimens.

Adult↗
PubMedDate not supplied

Testing human hair for drugs of abuse. II. Identification of unique cocaine metabolites in hair of drug abusers and evaluation of decontamination procedures.

Two unique metabolites of cocaine, cocaethylene and norcocaine, were identified by GC/MS in the hair of cocaine users. Their presence cannot be explained by environmental contamination; thus, their presence together with cocaine provides convincing evidence that cocaine is excreted in hair after active cocaine administration. The amount of cocaine in hair predominated over all metabolites generally by a factor of 5-10. Two washing procedures were evaluated for their efficiency in removal of cocaine from environmentally contaminated hair. Neither procedure completely removed cocaine, suggesting that false positives can result from environmental contamination. Analysis of the methanolic wash of the hair of cocaine users also revealed the presence of cocaine metabolites, indicating that washing removes cocaine from the interior as well as from the exterior surface of hair during decontamination procedures.

Adult↗
PubMedDate not supplied

Forensic drug testing for opiates. VI. Urine testing for hydromorphone, hydrocodone, oxymorphone, and oxycodone with commercial opiate immunoassays and gas chromatography-mass spectrometry.

Opiate testing for morphine and codeine is performed routinely in forensic urine drug-testing laboratories in an effort to identify illicit opiate abusers. In addition to heroin, the 6-keto-opioids, including hydromorphone, hydrocodone, oxymorphone, and oxycodone, have high abuse liability and are self-administered by opiate abusers, but only limited information is available on detection of these compounds by current immunoassay and gas chromatographic-mass spectrometric (GC-MS) methods. In this study, single doses of hydromorphone, hydrocodone, oxymorphone, and oxycodone were administered to human subjects, and urine samples were collected before and periodically after dosing. Opiate levels were determined in a quantitative mode with four commercial immunoassays, TDx opiates (TDx), Abuscreen radioimmunoassay (ABUS), Coat-A-Count morphine in urine (CAC), and EMIT d.a.u. opiate assay (EMIT), and by GC-MS. GC-MS assay results indicated that hydromorphone, hydrocodone, oxymorphone, and oxycodone administration resulted in rapid excretion of parent drug and O-demethylated metabolites in urine. Peak concentrations occurred within 8 h after drug administration and declined below 300 ng/mL within 24-48 h. Immunoassay testing indicated that hydromorphone, hydrocodone, and oxycodone, but not oxymorphone, were detectable in urine by TDx and EMIT (300-ng/mL cutoff) for 6-24 h. ABUS detected only hydrocodone, and CAC failed to detect any of the four 6-keto-opioid analgesics. Generally, immunoassays for opiates in urine displayed substantially lower sensitivities for 6-keto-opioids compared with GC-MS. Consequently, urine samples containing low to moderate concentrations of hydromorphone, hydrocodone, oxymorphone, and oxycodone will likely go undetected when tested by conventional immunoassays.

Enzyme Multiplied Immunoassay Technique↗
PubMedDate not supplied

Validity testing of the accuPINCH THC test.

Self-contained drug-testing kits are currently being marketed for a variety of drugs of abuse. These tests are designed to provide rapid access to test results without the need for laboratory facilities. This report describes a validity study of the accuPINCH THC test, a self-contained test for cannabinoids in urine. Three healthy male volunteers with a history of marijuana use participated in the clinical study. Each subject smoked one, two, or four marijuana cigarettes (2.6% THC) on each test day. Urine samples were collected and incorporated into a specimen set consisting of 178 clinical samples, 72 urine samples containing known amounts of drug, and 50 drug-free urine samples. The specimen set was randomized and analyzed under blind conditions by the accuPINCH test and by gas chromatography-mass spectrometry (GC-MS) for 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THCCOOH). AccuPINCH results were interpreted independently by three readers as positive at either two calibration points (positive A < 100 ng/mL THCCOOH; positive B > or = 100 ng/mL THCCOOH) or negative. Concordance analysis was performed by comparison of the accuPINCH results with GC-MS. In addition, the effects of changes in sample turbidity, temperature, and assay reading time on test outcome were assessed. For the clinical samples, positive B results were associated exclusively with THCCOOH concentrations greater than or equal to 15 ng/mL, whereas positive A and negative results were obtained at all concentrations. All drug-free urine samples were interpreted as either negative or positive A. The test demonstrated relatively low cross-reactivity with THC and other cannabinoids.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗