Quantitative determination of endogenous sorbitol and fructose in human erythrocytes by atmospheric-pressure chemical ionization LC tandem mass spectrometry

Evaluation of different extraction methods for quantification of endogenous sorbitol and fructose in human red blood cells (RBCs) and matrix effects in ESI and APCI showed that protein-precipitation followed by mixed-mode solid-phase extraction was more effective extraction method and APCI more effective ionization method. Then the LC/APCI-MS/MS method was fully validated and successfully applied to analysis of clinical RBC samples. The concentrations of endogenous sorbitol and fructose were determined using calibration curves employing sorbitiol-13C6 and fructose-13C6 as surrogate analytes. The method has provided excellent intra- and inter-assay precision and accuracy with a linear range of 50.0-10,000 ng/mL (correlation coefficient >0.999) for sorbitol-13C6 and 250-50000 ng/mL (correlation coefficient >0.999) for fructose-13C6 in human RBCs.

Quantitative determination of endogenous sorbitol and fructose in human nerve tissues by atmospheric-pressure chemical ionization liquid chromatography/tandem mass spectrometry

Attachment of anions to sorbitol and fructose has been shown to enhance sensitivity in both electrospray ionization (ESI) and atmospheric-pressure chemical ionization (APCI) mass spectrometry. The post-column addition of CHCl3 produced Cl-adducts of sorbitol and fructose but their signals were suppressed due to the elevated background. Different chlorinated compounds and different additive methods were systematically investigated to form more abundant Cl-adduct precursor ions and deprotonated product ions. The major causes of the high background were explored and effective methods were developed to improve the signal-to-noise ratios and reproducibility. The compositions of mobile phase, percentages of organic modifiers (MeCN, MeOH and water), columns, oven temperature, flow rates and different gradients were investigated to separate sorbitol from fructose along with their isomers including glucose, galactose, mannose, sorbose, mannitol, and dulcitol. The optimized separation was achieved on a Luna 5 mu NH2 100A column (150 x 4.6 mm) using a mobile phase containing MeCN with 0.1% of CH2Cl2 and 50% MeOH in water at a flow rate of 800 microL/min and an oven temperature of 40 degrees C using a gradient liquid chromatography (LC) system. Human nerve tissue samples were extracted by protein precipitation followed by mixed-mode solid-phase extraction. The LC/ESI-MS/MS method produced higher peak intensities than LC/APCI-MS/MS. However, there were matrix effects from extracted tissues in LC/ESI-MS/MS but not in LC/APCI-MS/MS. Consequently, APCI proved to be the more effective method of ionization. Then the LC/APCI-MS/MS method was fully validated and successfully applied to analysis of clinical samples. The concentrations of endogenous sorbitol and fructose were determined using calibration curves employing sorbitol-13C6 and fructose-13C6 as surrogate analytes. The method has provided excellent intra- and inter-assay precision and accuracy with linear ranges of 0.2-80 ng/mg for sorbitol and 1-400 ng/mg for fructose in human nerve tissues.

Method development and validation for quantitative determination of methadone enantiomers in human plasma by liquid chromatography/tandem mass spectrometry1

A high-throughput method for quantitative determination of methadone enantiomers in human plasma was developed and validated by liquid chromatography/tandem mass spectrometry. The effects of pH and of types and concentrations of mobile-phase modifiers on the enantioselectivity of (R)- and (S)-methadone were investigated on a Chiral-AGP column. A baseline separation of the enantiomers was achieved with a retention time of less than 5 min. Ionization suppression and other matrix effects were evaluated. Morphine, cocaine, 6-monoacetylmorphine, benzoylecgonine and ecgonine methyl ester did not interfere with the performance of the assay. The specificity, linearity, intra- and inter-assay precision and accuracy, and extraction recovery were fully evaluated. The method showed excellent reproducibility (overall coefficient of variance < 8%) and accuracy (overall bias < 2.7%) with a broad linear range. The enantiomers were stable in human plasma after five freeze-thaw cycles, under bench-top storage at room temperature (RT) for 6h, in the extract reconstitution solution at RT for 17 h, and in processed-extracts stored at RT for 142 h. This validated LC/MS/MS assay offers high-throughput and improved specificity, sensitivity, linear range and ruggedness over previously published methods and has been successfully applied to the analysis of clinical samples.

Ionization enhancement in atmospheric pressure chemical ionization and suppression in electrospray ionization between target drugs and stable-isotope-labeled internal standards in quantitative liquid chromatography/tandem mass spectrometry

The phenomena of ionization suppression in electrospray ionization (ESI) and enhancement in atmospheric pressure chemical ionization (APCI) were investigated in selected-ion monitoring and selected-reaction monitoring modes for nine drugs and their corresponding stable-isotope-labeled internal standards (IS). The results showed that all investigated target drugs and their co-eluting isotope-labeled IS suppress each other's ionization responses in ESI. The factors affecting the extent of suppression in ESI were investigated, including structures and concentrations of drugs, matrix effects, and flow rate. In contrast to the ESI results, APCI caused seven of the nine investigated target drugs and their co-eluting isotope-labeled IS to enhance each other's ionization responses. The mutual ionization suppression or enhancement between drugs and their isotope-labeled IS could possibly influence assay sensitivity, reproducibility, accuracy and linearity in quantitative liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). However, calibration curves were linear if an appropriate IS concentration was selected for a desired calibration range to keep the response factors constant.

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 7.0) prior to application to the solid-phase extraction columns. THC and THCA were eluted separately and then pooled, dried under air, and derivatized with trifluoroacetic anhydride and hexafluoroisopropanol. The derivatized THC-d0 gives abundant molecular anions (m/z 410), and the derivatized THCA-d0 gives abundant fragment ions (m/z 422) formed by loss of (CF3)2CHOH from its molecular anion. The recoveries of THC and THCA were 74% and 17%, respectively. The lower and upper limits of quantitation were 0.5 and 100 ng/mL for THC and 2.5 ng/mL and 100 ng/mL for THCA. The within-run accuracy and precision for THC (measured at 0.5, 1, 10 and 75 ng/mL) ranged from 98 to 106% (% target) and 4.1 to 9.5 (%CV), respectively. For THCA, the within-run accuracy and precision (measured at 2.5, 5, 10, and 75 ng/mL) ranged from 89 to 101% and 4.3 to 7.5%, respectively. The between-run accuracy and precision for THC ranged from 92 to 110% and 0.4 to 12.4%, respectively. The between-run accuracy and precision for THCA ranged from 97 to 103% and 6.5 to 12.3%, respectively. In processed samples stored in reconstituted form at -20 degrees C, THC and THCA were stable for at least three days. THC and THCA stored in plasma were stable following three freeze/thaw cycles. THC and THCA in whole blood at room temperature for 6 h, or in plasma stored at room temperature for 24 h, did not show significant change. Storage in polypropylene containers for 7 days at -20 degrees C and the presence of 1% sodium fluoride or the cannabinoid receptor antagonist, SR141716, at 1 microg/mL did not interfere with the quantitation of THC and THCA. In three individuals who smoked marijuana under controlled dosing conditions, peak THC concentrations of 151, 266, and 99 ng/mL were seen in the first plasma samples drawn immediately after the end of smoking, and corresponding peak THCA concentrations of 41, 52, and 17 ng/mL occurred at 0.33 to 1 h after cessation of smoking.

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. Cocaine recovery was 94.4% and benzoylecgonine was 80.3% at 2.5 ng/mL. The selected reaction monitoring of parent ions at m/z 304 and 290 resulted in strong fragments at m/z 182 and 168 for cocaine and benzoylecgonine, respectively. The method was fully validated. The mean measured concentration at the 2.5 ng/mL, the lower limit of quantitation, was within 10.8% of the target and the precision determined at the low (5 ng/mL), medium (50 ng/mL), and high (650 ng/mL) quality controls ranged from 0.9 to 6.2 %CV. Cocaine and benzoylecgonine concentrations in plasma treated with 1% NaF showed changes of less than 10% when maintained at room temperature for up to 7 h and no significant changes when subjected to three freeze-thaw cycles. The concentrations of cocaine and benzoylecgonine remained stable in plasma samples stored at -20 degrees C for up to 11 months. Methanolic stock solutions of both analytes are stable, staying within 2% of the freshly prepared stock solutions, when stored at -20 degrees C for up to 235 days. Both extracted analytes reconstituted in methanolic solutions are stable for up to seven days whether stored at -20 degrees C or at room temperature on the autosampler. The method is rugged, rapid, and robust and has been applied to the batch analysis of more than 700 samples during pharmacokinetic profiling to assess potential interactions between intravenous (i.v.) cocaine challenge and treament medications. Results from three of these subjects receiving 40 mg (i.v.) cocaine demonstrate the utility of the method.

Recent advances in chromatographic and mass spectrometric methods for determination of LSD and its metabolites in physiological specimens

The detection of LSD use continues to be a challenge for toxicology laboratories due to the very low concentrations of LSD and its metabolites in body fluids. However, significant progress has been made in the development of more sensitive and specific analytical methods. Techniques that have proven particularly effective include: (1) immunoaffinity extraction, (2) gas chromatography coupled with chemical ionization and tandem mass spectrometric detection, and (3) liquid chromatography in combination with electrospray ionization and either single-stage or tandem mass spectrometric detection. In addition, a major metabolite of LSD, 2-oxo-3-hydroxy-LSD, has been identified and found to be present in far higher concentrations than LSD in most LSD-positive urine samples.

Enantioselective gas chromatography-negative ion chemical ionization mass spectrometry for methylphenidate in human plasma

Therapeutic doses of Ritalin, a racemic mixture of d- and l-threo-methyphenidate, result in low plasma concentrations of methylphenidate. In order to assess the safety and efficacy of methylphenidate, a sensitive analytical method is needed. A gas chromatography-negative ion chemical ionization mass spectrometry (GC-NCI-MS) assay capable of measuring both d- and l-enantiomers in human plasma was developed and validated to support clinical studies involving administration of d,l-methylphenidate. d,l-Methylphenidate-d3 is added to 1-mL plasma samples. The plasma samples are made basic, mixed with isopropanol and extracted with hexane. The hexane extracts are then back-extracted into 0.1 N HCl. The acidified aqueous extract is made basic, cooled to ice temperature, and the methylphenidate derivatized with heptafluorobutyryl-l-prolyl chloride. The two diastereomeric derivatives are then extracted into hexane. The hexane extract is evaporated to dryness, reconstituted in ethyl acetate, and analyzed by GC-NCI-MS. This method can accurately (+/- 5% target) and precisely (< 11.1% coefficient of variation) quantitate enantiomers of threo-methylphenidate in human plasma and in the whole blood at concentrations ranging from 0.75 to 100 ng/mL. Plasma samples are stable for up to five freeze-thaw cycles when the duration of each cycle did not exceed 0.5 h. The drug degraded gradually when plasma samples were left at room temperature; a 6% loss at 3 h progressed to 17% at 12 h and to 35% at 24 h. Therefore, it is important that extraction of plasma samples begins within 0.5 h after samples are removed from the freezer. Whole blood stability results show that concentrations of methylphenidate in whole blood, with or without NaF, stored for up to 6 h at room temperature did not deviate from the target concentration by more than 13%. The derivatized methylphenidate in extract is stable at 4 degrees C for up to 10 days.

Quantitative determination of LSD and a major metabolite, 2-oxo-3-hydroxy-LSD, in human urine by solid-phase extraction and gas chromatography-tandem mass spectrometry

An assay has been developed for quantitative determination of lysergic acid diethylamide (LSD) and a major metabolite of LSD in human urine at concentrations as low as 10 pg/mL. In most LSD-positive urine samples the metabolite, 2-oxo-3-hydroxy-LSD, is present at higher concentrations than LSD and can be detected for a longer time than LSD after ingestion of the drug. Urine samples are extracted using Varian Bond Elut Certify extraction cartridges. Confirmatory identification is accomplished by trimethylsilylation of LSD and 2-oxo-3-hydroxy-LSD, followed by gas chromatography-tandem mass spectrometry analysis using positive ion chemical ionization and selected reaction monitoring. Commercially available lysergic acid methylpropylamide and 2-oxo-3-hydroxy-LAMPA are used as internal standards. With selected reaction monitoring, both compounds gave linear calibration curves from 10 pg/mL to 5000 pg/mL. Forty-nine human urine samples that had previously been shown to contain LSD were reanalyzed by the new method. These samples showed an average LSD concentration of 357 pg/mL and an average 2-oxo-3-hydroxy-LSD concentration of 3470 pg/mL. Additional experiments using clinical samples in which two subjects were dosed with LSD support the conclusion that analysis for 2-oxo-3-hydroxy-LSD can permit identification of LSD users for a longer period following ingestion than analysis for the parent drug.

Determination of buprenorphine in human plasma by gas chromatography-positive ion chemical ionization mass spectrometry and liquid chromatography-tandem mass spectrometry

Buprenorphine is used for the management of pain and has been advocated for the treatment of opioid addiction. Therapeutic doses result in low plasma concentrations of buprenorphine. In order to assess the safety and efficacy of buprenorphine, sensitive analytical methods are needed. Until recently, gas chromatography-positive ion chemical ionization mass spectrometry (GC-PCI-MS) offered the most sensitive method to selectively quantitate buprenorphine. We have developed and validated a sensitive liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) method for buprenorphine. The method is described and compared with a GC-PCI-MS method validated in this laboratory. One-milliliter aliquots of plasma are required for the LC-ESI-MS-MS method and 2-mL aliquots for the GC-PCI-MS method. Buprenorphine-d4 is used as internal standard for both methods. Derivatization with pentafluoropropionic acid anhydride is used for the GC-PCI-MS method, in which the derivatized protonated molecular ions after loss of water are monitored at m/z 596 and 600. For LC-ESI-MS-MS, the parent protonated molecule ions are monitored at m/z 468 and 472. A single-step extraction of basic plasma with n-butyl chloride provided recoveries of 70-87%. Although a limit of quantitation (LOQ) of 0.1 ng/mL could be established for LC-ESI-MS-MS, we could only achieve an LOQ of 0.5 ng/mL with the GC-PCI-MS assay. The GC-PCI-MS method has a linear range of 0.5 to 40 ng/mL (mean r2 = 0.998, n = 7). For quality control samples at 1.0, 2.5, and 12.5 ng/mL, the intra- and interassay coefficients of variation (CV) did not exceed 14%, and percent of targets were within 16%. The LC-ESI-MS-MS method had a linear range of 0.1 to 10 ng/mL (mean r2 = 0.999, n = 7). For quality control samples at 0.25, 2.5 and 7.5 ng/mL, the intra- and interassay CVs did not exceed 4%, and percent of targets were within 12%. Stability studies demonstrated buprenorphine was stable for up to 24 h, 125 days, and 55 days when stored at room temperature, 4 degrees C, and -20 degrees C, respectively. The utility of the lower LOQ was demonstrated in 40 plasma samples collected up to 96 h after a sublingual dose of buprenorphine; 10 were quantitatable using GC-PCI-MS and 38 using LC-ESI-MS-MS.

Clinical pharmacokinetics of escalating i.v. doses of dexanabinol (HU-211), a neuroprotectant agent, in normal volunteers

The pharmacokinetics of dexanabinol (HU-211), a synthetic, nonpsychotropic cannabinoid with neuroprotectant action, was evaluated in a phase I clinical trial. The compound was administered at doses of 48 mg, 100 mg, and 200 mg as short i.v. infusions in a Cremophor-ethanol vehicle diluted with saline. All administrations were well-tolerated and no compound-related side-effects were observed. Plasma concentrations of dexanabinol were quantitated using a GC/MS/MS technique which provided a limit of quantitation of 100 pg/ml. The elimination of dexanabinol was best fitted to a 3-compartment model with a rapid distribution half-life (< 5 min), an intermediate phase half-life of approximately 90 min, and a slow terminal elimination half-life (approximately 9 h). The pharmacokinetics were linear over the evaluated dose range. The plasma clearance of the drug was high (1,700 ml/min) and the volume of distribution approximately 15 l/kg. These data are similar to those reported for naturally occurring cannabinoids such as delta 9-tetrahydrocannabinol and cannabidiol.

Determination of naltrexone and 6-beta-naltrexol in plasma by solid-phase extraction and gas chromatography-negative ion chemical ionization-mass spectrometry

Solid-phase extraction (SPE) and a one-step derivatization are combined with gas chromatography-negative ion chemical ionization-mass spectrometry to simplify a previously reported method for the determination of naltrexone and its metabolite, 6-beta-naltrexol, in human plasma. Deuterated isotopomers of naltrexone and 6-beta-naltrexol are used as internal standards. After SPE, the extracts are derivatized with pentafluoropropionic anhydride at room temperature to form predominantly the bispentafluoropropionyl derivative of naltrexone and the trispentafluoropropionyl derivative of 6-beta-naltrexol. The derivatized extracts are analyzed by monitoring ion currents at m/z 633 (naltrexone), m/z 636 (naltrexone-2H3), m/z 633 6-beta-naltrexol), and m/z 640 (6-beta-naltrexol-2H7). Control plasma samples containing 0.3, 3, or 30 ng/nl of each analyte were analyzed for precision and accuracy with the following results: intra-assay, the percentage of target concentrations were 107-113% for naltrexone and 107-120% for 6-beta-naltrexol, and the coefficients of variation (CVs) were 3.1-6.3% for naltrexone and 3.1-5.7% for 6-beta-naltrexol; interassay, the percentage of target concentrations were 103-110% for naltrexone and 110-113% for 6-beta-naltrexol, and the CVs were 6.1-9.1% for naltrexone and 5.9-9.1% for 6-beta-naltrexol. At the limit of quantitation (LOQ) of 0.1 ng/ml, both analytes quantified within 20% of the target concentration with CVs less than 17%. The extraction recoveries determined at 0.3 and 30 ng/ml were 79 and 80% for naltrexone and 76 and 75% for 6-beta-naltrexol. Bench-top stability tested with concentrations of 0.3 and 3.0 ng/ml did not decrease more than 10% from the zero-hour controls at 3, 6 and 24 h. Selectively was determined using plasma from six donors and none showed interfering peaks greater than 22% of the LOQ for naltrexone and 53% of the LOQ for 6-beta-naltrexol. Using this method, naltrexone and 6-beta-naltrexol were readily detected in plasma specimens collected 5.5 h after oral doses of 25 or 100 mg naltrexone. Following discontinuation of treatment, naltrexone was detected 30 h after the 100-mg dose, whereas 6-beta-naltrexol was detected 125 h after both the 25- and 100-mg doses.

Quantitative analysis of methadone and two major metabolites in hair by positive chemical ionization ion trap mass spectrometry

A sensitive and specific method for the quantitative determination of D,L-methadone (MD) and its metabolites, D,L-2-ethyl-1,5-dimethyl-3, 3-diphenylpyrrolinium (EDDP) and D,L-2-ethyl-5-methyl-3, 3-diphenyl-1-pyrroline (EMDP), in hair has been developed. Deuterated internal standards of MD, EMDP, and EDDP were added to 20-mg hair samples and digested overnight at room temperature with 1N sodium hydroxide. Calibration standards containing known concentrations of MD, EMDP, and EDDP dried onto human hair were also digested. Digest solutions were extracted by a liquid-liquid extraction procedure and analyzed with splitless injection on a Finnigan MagnumTM ion trap mass spectrometer. Chromatographic separation was achieved with helium carrier gas on a DB-5MS-30M-0.25-micron capillary column. Positive chemicaionization was used with acetone as the reagent gas. The assay was linear from 0.5 ng/mg (MD and EDDP) or 1.0 ng/mg (EMDP) to 50.0 ng/mg of human hair with correlation coefficients greater than 0.99. Intra-assay and interassay coefficients of variation were determined to be less than 20% for all three analytes at 2.0 and 10.0 ng/mg of hair. Recovery was estimated to be greater than 70% (MD and EDDP) and 53% (EMDP) at 2.0 and 10.0 ng/mg of hair. The method has been applied to the analysis of both human and rat hair. Male long-Evans rats were shaved prior to dosing to obtain their drug-free hair. Animals were then administered 15 mg/kg MD by intraperitoneal injection daily for five days. Fourteen days after the first dose, hair was collected and analyzed for MD, EMDP, and EDDP. The mean plus standard error of the mean (SEM; n = 3) concentrations of MD and EDDP in pigmented hair were 31.1 ng/mg +/- 9.6 ng/mg and 8.6 +/- 2.4 ng/mg, respectively. EMDP was detected in the hair of one of three rats. In another experiment, hair was collected from two human subjects who had received long-term methadone therapy for the treatment of heroin addiction. Subject A received 60 mg of methadone daily for at least six months; subject B received 80 mg of methadone daily for at least six months. The hair concentrations of MD were 10.1 ng/mg and 21.0 ng/mg for Subjects A and B, respectively. The hair concentrations of EDDP were 0.5 ng/mg and 2.6 ng/mg for Subjects A and B, respectively. EMDP was not detected in the hair of these two subjects. This method is being used to evaluate the incorporation of MD, EMDP, and EDDP in human and rat hair in dose-response studies.

Determination of methadone and its N-demethylation metabolites in biological specimens by GC-PICI-MS

Methadone is often invoked for detoxification and maintenance of the opioid addict. We have developed and validated a sensitive and specific method for the analysis of methadone and its metabolites, 2-ethylidene-1,5-dimethyl-3, 3-diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenylpyrroline (EMDP), in human plasma, urine, and liver microsomes. This assay uses a solid-phase extraction. Separation and analysis of the analytes are performed by capillary gas chromatography-positive ion chemical ionization-mass spectrometry. The protonated molecules (MH+) are monitored at m/z 264 and 267 for EMDP-d0 and -d3, m/z 278 and 281 for EDDP-d0 and -d3, and m/z 310 and 313 for methadone-d0 and -d3. The recovery of methadone and its metabolites exceeded 85% in the different matrices analyzed. Linear standard curves in plasma and in urine were obtained over the concentration range of 10-600 ng/mL (coefficients of determination: methadone, > or = 0.995; EMDP, > or = 0.994; and EDDP, > or = 0.996). With plasma and urine fortified at 25, 100, and 300 ng/mL, the assay was precise (intra-assay coefficients of variation [CVs], 2-12%; interassay CVs, 1-15%) and accurate (intra-assay percent of target, 85-107; interassay percent of target, 88-105) for all three analytes. Stability studies indicated that methadone and its metabolites are stable at room temperature in plasma and in urine for at least 1 week and in liver microsomes for at least 24 h. This method has now been shown to be useful for quantitation of methadone, EDDP, and EMDP in human urine and plasma and is also useful for quantitation of the amount of EDDP produced in human liver microsomes incubated with methadone. It provides an accurate and precise analytical tool for further studies on the metabolism of methadone.

Quantitative determination of phencyclidine in pigmented and nonpigmented hair by ion-trap mass spectrometry

A sensitive and specific method has been developed for the quantitative analysis of phencyclidine (PCP) in pigmented and nonpigmented rat hair. After the addition of PCP-d5 as the internal standard, hair samples (10 mg) were digested overnight in 1N NaOH at 30 degrees C. Digested solutions were then extracted using a solid-phase procedure with Bond Elut CertifyTM extraction columns. Reconstituted extracts were analyzed on a Finnigan ion trap (MagnumTM) mass spectrometer in the electron ionization mode using helium as the carrier gas, and a DB-5 MS (30 m x 0.25-mm i.d.; 25-microns film thickness) capillary column. The assay is linear from 0.1 to 50 ng/mg with a correlation coefficient of > 0.99 and is capable of detecting 25 pg of PCP on column. The accuracy of this assay was estimated using fortified hair standards at PCP concentrations of 0.5 and 10 ng/mg. Intra-assay coefficients of variation were determined to be less than 6% at 0.5, 2, and 10 ng/mg. Interassay coefficients of variation were determined to be less than 15% at 0.5, 2, and 10 ng/mg. The method has been used to evaluate PCP incorporation into Long-Evans rat hair but could also be used to evaluate the incorporation of PCP into human hair. Male rats were shaved prior to dosing such that both pigmented and nonpigmented hair was collected. Animals were administered 12 mg/kg PCP by intraperitoneal injection daily for five days. Fourteen days after the first dose, pigmented and nonpigmented hair were collected and analyzed for PCP. The mean plus or minus the standard error of the mean (n = 5) concentrations of PCP in pigmented and nonpigmented hair were 14.33 +/- 1.43 ng/mg of hair and 0.47 +/- 0.04 ng/mg of hair, respectively. This method is also being used to evaluate PCP as a model xenobiotic for studies of the incorporation of xenobiotics into hair.

Detection of LSD and metabolite in rat hair and human hair

To examine the feasibility of detecting lysergic acid diethylamide (LSD) and its metabolites in hair, LSD was administered to rats with pigmented hair at 0.05, 0.1, 0.5, 1, and 2 mg/kg intraperitoneally once per day for 10 successive days. The rats were shaved just before the first administration, and newly grown hair was collected 4 weeks later. After being washed with 0.1% sodium dodecyl sulfonate and water and being dried in a desiccator, each 20-mg hair sample was extracted with 2 mliter methanol-5N HCl (20:1) under ultrasonication for 1 h and stored at room temperature for 14 h. The extract was evaporated to dryness, extracted from 0.1M NaOH with dichloromethane, and derivatized with a mixture of trimethylsilylimidazole, bis-(trimethylsilyl)acetamide, and trimethylchlorosilane (3:3:2, v/v/v) for gas chromatographic-mass spectrometric (GC-MS) analysis using LSD-d10 or lysergic acid methylpropylamide (LAMPA) as the internal standard. Selected ions were monitored at m/z 395, 293, and 279 for TMS-LSD and at m/z 381, 279, and 254 for the trimethylsilyl derivative of N-demethyl-LSD (TMS-norLSD). LSD and norLSD were also detected by high-performance liquid chromatography (HPLC) with fluorometric detection (excitation, 315 nm; emission, 420 nm). LSD was detected in the rat hair following the lowest dose (0.05 mg/kg), whereas norLSD was only detectable in the hair following the highest dose (2 mg/kg). The same GC-MS and HPLC assays were applied to the analysis of hair from 17 self-reported LSD users, and LSD was detected in two of the samples.

Determination of ibogaine and 12-hydroxy-ibogamine in plasma by gas chromatography-positive ion chemical ionization-mass spectrometry

Ibogaine, an indolamine derivative, is currently being investigated as a potential agent in the treatment of stimulant and opiate addiction. We developed a rapid, sensitive, and specific method for the analysis of ibogaine and its putative active metabolite, 12-hydroxy-ibogamine (12-OH-ibogamine). This assay employs a one-step basic extraction with n-butyl chloride-acetonitrile (4:1), followed by derivatization of the metabolite using N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide. The derivatized extracts were analyzed by capillary gas chromatography-positive ion chemical ionization-mass spectrometry. The ions monitored were at m/z 311, 314, and 411, which correspond to the protonated molecules (MH+) for ibogaine, ibogaine-d3, and 12-OH-ibogamine.tert-butyldimethylsilyl, respectively. Linear standard curves were obtained over the concentration range of 1 0-1 000 ng/mL (average r2, 0.995 for ibogaine and 0.992 for 12-OH-ibogamine; n = 3). Limits of quantitation were 10 ng/mL. The interrun and intrarun coefficients of variation for the assay of ibogaine at 25, 100, and 300 ng/mL ranged from 2.9 to 8.8%. We also established the extraction and chromatographic conditions to monitor the 12-hydroxylated metabolite. A suitable internal standard was not yet obtained so the method could only provide semiquantitative information for 12-OH-ibogamine. Chemical stability studies of these analytes indicated that ibogaine and 12-OH-ibogamine were stable in a human plasma matrix at room temperature for a period of at least 1 week.

A gas chromatographic-positive ion chemical ionization-mass spectrometric method for the determination of I-alpha-acetylmethadol (LAAM), norLAAM, and dinorLAAM in plasma, urine, and tissue

l-alpha-Acetylmethadol (LAAM) is approved as a substitute for methadone for the treatment of opiate addiction. Analytical methods are needed to quantitate LAAM and its two psychoactive metabolites, norLAAM and dinorLAAM, to support pharmacokinetic and other studies. We developed a gas chromatographic-positive ion chemical ionization-mass spectrometric method for these analyses. The method uses 0.5 mL urine or 1.0 mL plasma or tissue homogenate, deuterated (d3) isotopomers as internal standards, methanolic denaturation of protein (for plasma and tissue), and extraction of the buffered sample with n-butyl chloride. For tissue homogenates, an acidic back extraction is included. norLAAM and dinorLAAM were derivatized with trifluoroacetic anhydride. Chromatographic separation of LAAM and derivatized norLAAM and dinorLAAM is achieved with a 5% phenyl methylsilicone capillary column. Positive ion chemical ionization detection using methane-ammonia as the reagent gas produces abundant protonated ions (MH+) for LAAM (m/z 354) and LAAM-d3 (m/z 357) and ammonia adduct ions (MNH4+) for the derivatized norLAAM (m/z 453), norLAAM-d3 (m/z 45 6), dinorLAAM (m/z 439), and dinorLAAM-d3 (m/z 442). The linear range of the calibration curves were matrix dependent: 5-300 ng/mL for plasma, 10-1000 ng/mL for urine, and 10-600 ng/g for tissue homogenates. The low calibrator was the validated limit of quantitation for that matrix. The method is precise and accurate with percent coefficients of variation and percent of targets within 13%. The method was applied to the analysis of human urine and plasma samples; rat plasma, liver, and brain samples; and human liver microsomes following incubation with LAAM.

Gas chromatography/tandem mass spectrometry measurement of delta 9-tetrahydrocannabinol, naltrexone, and their active metabolites in plasma

The combination of gas chromatography and mass spectrometry (GC/MS) is generally recognized as offering the best sensitivity and specificity for the detection and measurement of drugs and their metabolites in biological specimens. This finding has resulted in the widespread use of GC/MS in many areas of pharmacology and toxicology. However, a GC/MS assay can be performed in many ways, depending upon the specific requirements of the analytical tasks. For example, pharmacokinetic studies generally employ chemical ionization and single-ion monitoring to obtain optimum sensitivity, whereas GC/MS methods for confirmation of the presence of drugs of abuse in urine most often use electron ionization and multiple-ion monitoring to obtain conclusive results. Another example is the increasing use of the combination of gas chromatography and tandem mass spectrometry (GC/MS/MS) for analyses requiring sensitivities better than nanograms per milliliter. Examples of the application of GC/MS and GC/MS/MS methods for the detection of delta 9-tetrahydrocannabinol, naltrexone, and their active metabolites are described and compared in terms of sensitivity, specificity, and unique features.

Stereoselective disposition: enantioselective quantitation of 3,4-(methylenedioxy) methamphetamine and three of its metabolites by gas chromatography/electron capture negative ion chemical ionization mass spectrometry

A new chiral assay for 3,4-(methylenedioxy)methamphetamine (MDMA) and three of its metabolites in biological specimens is based on direct aqueous derivatization with N-heptafluorobutyryl-S-prolyl chloride, followed by capillary chromatographic separation of the diastereomeric derivatives and detection by a mass spectrometer operated in the electron capture negative ion chemical ionization mode. The assay is linear from 5 to 1000 ng ml-1 for each enantiomer and allows simultaneous quantitation of MDMA and three of its metabolites in biological specimens. Investigation of the disposition of racemic MDMA in rats and mice revealed quantitative differences in the disposition of the enantiomers of MDMA in these species; the most noteworthy result was a two-fold greater urinary excretion of the neurotoxic S-(+)-MDMA by mice. Only MDMA and 3,4-(methylenedioxy)amphetamine (MDA) enantiomers were detected at measurable concentrations in the frontal cortices and hippocampis from rats dosed with 10 mg kg-1 of racemic MDMA; in this species the enantiomeric profiles of these two compounds were similar in brain and urine.

Short-term effects of 2,4,5-trihydroxyamphetamine, 2,4,5-trihydroxymethamphetamine and 3,4-dihydroxymethamphetamine on central tryptophan hydroxylase activity

In previous studies, we have reported the long-term effects of several metabolites of 3,4-methylenedioxymethamphetamine (MDMA) on tryptophan hydroxylase (TPH) activity. In this study, the short-term effects of three metabolites of MDMA. 2,4,5-trihydroxyamphetamine (THA), 2,4,5-trihydroxymethamphetamine (THM) and 3,4-dihydroxymethamphetamine, and the in vitro effect of THA on TPH activity are reported. After short-term treatment, hippocampal TPH activity was decreased to 8 and 54% of control in response to THA and THM, respectively, but was unaltered after 3,4-dihydroxymethamphetamine. Incubating TPH from THM-treated rats with dithiothreitol under nitrogen failed to reverse the decrease in enzyme activity induced by THM treatment. THA also decreased tyrosine hydroxylase activity to 75% of control, whereas the enzyme activity remained unaltered by THM. The structural analog of THA, 6-hydroxydopamine, failed to reproduce the effect of THA on TPH activity; however, 5,6-dihydroxytryptamine decreased hippocampal TPH activity to 18% of control. In the in vitro study, the hippocampus and the striatum were incubated in varying concentrations of THA. After a 1-h incubation at 37 degrees C, hippocampal TPH activity was decreased to 83, 71, 68, 47 and 3% of control after exposure to 0.001, 0.01, 0.1, 0.5 or 5.0 mM THA, respectively; striatal TPH activity was reduced to 98, 95, 70, 54 and 17% of control, respectively. Incubating the enzyme under reducing conditions failed to restore the enzyme activity to control levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative investigation of disposition of 3,4-(methylenedioxy)methamphetamine (MDMA) in the rat and the mouse by a capillary gas chromatography-mass spectrometry assay based on perfluorotributylamine-enhanced ammonia positive ion chemical ionization

A gas chromatography-mass spectrometry assay based on perfluorotributylamine-enhanced ammonia positive ion chemical ionization has been developed for MDMA and three of its primary metabolites in biological specimens; the assay is linear from 2 to 1000 ng ml-1. Quantitatively, more of an administered dose of 10 mg kg-1 MDMA was excreted by the mouse (72%) than by the rat (35%); most in both species was excreted in urine and within 24 h. The difference in per cent excretion is entirely due to proportionally greater excretion of the parent drug by the mouse. 4-Hydroxy-3-methoxymethamphetamine (HMM) is the major urinary metabolite in both species. HMM and another primary metabolite, 4-hydroxy-3-methoxyamphetamine (HMA), were excreted mainly as glucuronide and sulphate conjugates (> 85%).

Long-term alteration in the central monoaminergic systems of the rat by 2,4,5-trihydroxyamphetamine but not by 2-hydroxy-4,5-methylenedioxymethamphetamine or2-hydroxy-4,5-methylenedioxyamphetamine

The long-term effects of three metabolites of 3,4-methylenedioxymethamphetamine (MDMA) on the central monoaminergic systems of the rat were examined. Seven days after the intracerebroventricular administration of 0.25 and 0.5 mumol 2,4,5-trihydroxyamphetamine, hippocampal tryptophan hydroxylase (TPH) activity was reduced to 5 and 1% of control, respectively, while norepinephrine (NE) concentration was depressed to 10 and 18% of control. These two respective dosages also decreased striatal tyrosine hydroxylase (TH) activity to 67 and 10% of control, respectively, while nigral TH activity was reduced to 59 and 20% of control. Striatal TPH activity was reduced to 74 and 81% of control, respectively, while the activity in the dorsal and median raphe remained unaltered. The intracerebroventricular administration of 1 mumol 2-hydroxy-4,5-methylenedioxymethamphetamine (6-OH-MDMA) failed to alter TPH activity, TH activity or NE concentration after 14 days. In contrast, 1 mumol of 2-hydroxy-4,5-methylenedioxyamphetamine (6-OH-MDA) induced a 30% increase in striatal TPH activity and a 50% increase in nigral TH activity. The study of the formation of 2,4,5-trihydroxyamphetamine after MDMA treatment may provide insight as to how MDMA destroys serotonergic nerve terminals.

Chromatographic and mass spectrometric methods for determination of lysergic acid diethylamide (LSD) and metabolites in body fluids

Continued illicit use of the potent psychedelic drug lysergic acid diethylamide (LSD) has stimulated efforts to develop effective analytical methods for detection of the drug and its metabolites in body fluids from suspected LSD users. Recently reported methods based on gas and liquid chromatography, combined with single- and multiple-stage mass spectral analysis, now permit accurate detection and quantitation of LSD at sub-nanogram/milliliter concentrations.

Determination of lysergic acid diethylamide (LSD), iso-LSD, and N-demethyl-LSD in body fluids by gas chromatography/tandem mass spectrometry

Procedures for detection and quantitation of lysergic acid diethylamide (LSD), iso-LSD, and N-demethyl-LSD by capillary chromatography/tandem mass spectrometry (GC/MS/MS) are presented. Several methods for derivatization, sample introduction, and ionization, in combination with mass spectrometry/mass spectrometry (MS/MS), have been evaluated for overall ionization efficiency and product-ion sensitivity and specificity. Fragmentation pathways derived from low-energy collision-induced dissociation (CID) spectra of protonated LSD, and the protonated trimethylsllyl derivatives of LSD (LSD-TMS) and deuterium-labeled analogs of LSD, have been proposed. Principal dissociations primarily involve the amide and piperidine-ring moieties in which losses of CH3 radical, CH3NH2, CH3NCH2, diethylamine, diethylformamide, and N,N-diethylpropenamide from MH+ are observed. Positive-ion ammonia chemical ionization and subsequent MS/MS analysis of the protonated molecules (MH+) of the trimethylsilyl (TMS) derivatives of LSD, iso-LSD, and N-demethyl-LSD provide a high degree of specificity for identification of these compounds in urine or blood at low-pg/mL concentrations. Negative-ion chemical ionization and GC/MS/MS analysis of the molecular anion (M-) of the trifluoroacetyl (TFA) derivative is well suited for trace-level identification of N-demethyl-LSD, a metabolite of LSD.

Effects of 3,4-dihydroxymethamphetamine and 2,4,5-trihydroxymethamphetamine, two metabolites of 3,4-methylenedioxymethamphetamine, on central serotonergic and dopaminergic systems

The effects of 3,4-dihydroxymethamphetamine (DHM) and 2,4,5-trihydroxymethamphetamine (THM) on central serotonergic and dopaminergic systems were investigated to determine if these metabolites share the neurochemical properties of 3,4-methylenedioxymethamphetamine. THM (50-200 micrograms) or DHM (135 micrograms) was administered i.c.v. to rats; 5 days later, cortical, striatal and hippocampal tryptophan hydroxylase (TPH) activity were decreased by THM in a dose-dependent manner, whereas DHM was without effect in these brain structures. The concentration of serotonin in the brain structures contralateral to the side of THM injection was also decreased, but to a lesser degree. THM (100 and 200 micrograms) increased TPH activity to 155% of control in the dorsal raphe, whereas a dose of 50 micrograms increased TPH activity to 132% of control in the median raphe nucleus. THM also markedly reduced striatal tyrosine hydroxylase activity, but did not alter enzyme activity in the substantia nigra; DHM increased striatal tyrosine hydroxylase activity to 115% of control. These results suggest that THM, but not DHM, is toxic to both dopaminergic and serotonergic nerve terminals. Although THM could not be established as the neurotoxic metabolite explaining 3,4-methylenedioxymethamphetamine (MDMA) toxicity, its properties may prove useful in elucidating amphetamine toxicity.

In vivo formation of aromatic hydroxylated metabolites of 3,4-(methylenedioxy)methamphetamine in the rat: identification by ion trap tandem mass spectrometric (MS/MS and MS/MS/MS) techniques

Aromatic hydroxylation has been established as a pathway for the in vivo metabolism of 3,4-(methylenedioxy)methamphetamine (MDMA) in the rat. Hydroxylation occurred at positions 2, 5 and 6 of the 3,4-methylenedioxyphenyl ring, but is favored at the 6 position. All three regioisomers of both hydroxy-MDMA and hydroxy-3,4-(methylenedioxy)amphetamine (hydroxy-MDA) were detected in the rat liver when 20 mg kg-1 of MDMA was administered. However, 6-hydroxy-MDMA and 6-hydroxy-MDA were the only hydroxylated metabolites detected in the rat brain and plasma and no hydroxylated metabolites were detected in the urine. The hydroxylated metabolites were identified by co-injection of synthetic reference compounds and comparison of the mass spectra of the trifluoroacetyl derivatives of the metabolites with the synthesized reference compounds. The regioisomers of both hydroxy-MDMA and hydroxy-MDA could not be distinguished by either single-stage or two-stage mass analysis. However, employment of a third stage of mass analysis produced distinctly different mass spectra for each of the three regioisomers.

Analysis of naltrexone and 6-beta-naltrexol in plasma and urine by gas chromatography/negative ion chemical ionization mass spectrometry

A procedure for the analysis of naltrexone and 6-beta-naltrexol in plasma and urine samples is described. The method takes advantage of the specificity of negative ion chemical ionization mass spectrometry and the resolving power of capillary column chromatography to achieve a limit of quantitation of 0.1 ng/mL. The trideuterated analogs of naltrexone and 6-beta-naltrexol are used as internal standards. Samples are first made basic with K2HPO4 buffer (50% w/v), and then extracted twice with n-butyl chloride-acetonitrile (4:1). After back extraction into 0.2 N H2SO4, the samples are again extracted with n-butyl chloride-acetonitrile. The extracts are derivatized with 2% methoxyamine in pyridine and pentafluoropropionic anhydride to form the methoxime bis-(pentafluoropropionyl) derivative of naltrexone and the tris-(pentafluoropropionyl) derivative of 6-beta-naltrexol. The derivatized extracts are analyzed by selected ion monitoring of prominent ions formed by electron-capture negative ion chemical ionization.

Comparison of a TLC method with EMIT and GC/MS for detection of cannabinoids in urine

Urine specimens were analyzed in parallel with a new TLC method, an EMIT assay, and a reference GC/MS method. At a 9-carboxy-THC cutoff of 20 ng/mL, the TLC method correctly identified 92% of the positive urines and 97% of the negative urines. In contrast, only 63% of the urine specimens shown by GC/MS to contain greater than 20 ng/mL of 9-carboxy-THC were identified as positive by the EMIT d.a.u. assay at the 100-ng/mL cannabinoid cutoff.

Cocaine metabolism in man: identification of four previously unreported cocaine metabolites in human urine

Cocaine and 11 of its metabolites were identified in a urine specimen from a cocaine user. Four of the metabolites are reported for the first time: ecgonidine, norecgonidine methyl ester, norecgonine methyl ester, and m-hydroxy-benzoylecgonine. The structures of the newly identified metabolites were confirmed by comparison of their gas chromatographic retention times and their electron ionization and chemical ionization mass spectra with the corresponding data obtained on synthesized standards. Other metabolites present were benzoylecgonine, ecgonine methyl ester, ecgonine, ecgonidine methyl ester, norcocaine, p-hydroxycocaine, and m-hydroxycocaine.

Measurement of lysergic acid diethylamide (LSD) in human plasma by gas chromatography/negative ion chemical ionization mass spectrometry

A previously reported procedure for quantification of LSD in urine was modified to permit measurement of the drug in plasma. After addition of deuterium-labelled LSD, the plasma is extracted and the extract is treated with trifluoroacetylimidazole to convert the LSD to its N-trifluoroacetyl derivative. The derivatized LSD is analyzed by capillary column gas chromatography/negative ion chemical ionization. Plasma fortified with known concentrations of LSD gave linear responses from 0.1 to 3.0 ng/mL with this assay. The method was used to determine pharmacokinetic parameters for LSD after oral administration (1 microgram/kg) to a male volunteer. The apparent plasma half-life was determined to be 5.1 h. The peak plasma concentration of 1.9 ng/mL occurred 3 h after administration.

Naltrexone in autistic children: an acute open dose range tolerance trial

The safety and efficacy of naltrexone was explored in an open acute dose range tolerance trial in 10 hospitalized autistic children, ages 3.42 to 6.50 years (mean, 5.04). Naltrexone was given in ascending doses: 0.5, 1.0, and 2.0 mg/kg/day. Behavioral side effects were observed as early as 1/2 hour after dosing. Ratings on the Children's Psychiatric Rating Scale showed that withdrawal was reduced across all three dose levels; administration of 0.5 mg/kg/day dose resulted in increased verbal production; and the 2.0 mg/kg/day dose resulted in reduction of sterotypies. Mild sedation of brief duration was the only side effect. Electrocardiogram, liver function tests, and all other laboratory studies remained unchanged throughout the study. These preliminary findings require replication in a larger sample of patients under double-blind and placebo controlled condition.

In vivo and in vitro metabolism of 3,4-(methylenedioxy)methamphetamine in the rat: identification of metabolites using an ion trap detector

Four biotransformation pathways of 3,4-(methylenedioxy)methamphetamine (MDMA) in the rat have been identified: N-demethylation, O-dealkylation, deamination, and conjugation (O-methylation, O-glucuronidation, and/or O-sulfation). The specific MDMA metabolites that have been identified are 3-hydroxy-4-methoxymethamphetamine, 4-hydroxy-3-methoxymethamphetamine, 3,4-dihydroxymethamphetamine, 4-hydroxy-3-methoxyamphetamine, 3,4-(methylenedioxy)amphetamine (MDA), (4-hydroxy-3-methoxyphenyl)acetone, [3,4-(methylenedioxy)phenyl]acetone, and (3,4-dihydroxyphenyl)acetone. All except 3,4-dihydroxymethamphetamine were present in the urine. The hydroxylated metabolites were excreted in the urine as the O-glucuronide and/or O-sulfate conjugates, but traces of free 4-hydroxy-3-methoxymethamphetamine and 4-hydroxy-3-methoxyamphetamine were also present in unhydrolyzed urine. N-Demethyl and 3-O-methyl phenolic amine metabolites of MDMA were consistently present in brain, liver, blood, and feces. MDMA was metabolized by the 10000g rat liver supernatant to 4-hydroxy-3-methoxymethamphetamine, 3,4-dihydroxymethamphetamine, MDA, and [3,4-(methylenedioxy)phenyl]acetone. Also, the 10000g rat brain supernatant metabolized MDMA to 4-hydroxy-3-methoxymethamphetamine, 3,4-dihydroxymethamphetamine, 4-hydroxy-3-methoxyamphetamine, and MDA.

Determination of LSD in urine by capillary column gas chromatography and electron impact mass spectrometry

A procedure for the determination of LSD (lysergic acid diethylamide) in urine at concentrations as low as 0.5 ng/ml is presented. After addition of deuterium-labeled LSD as the internal standard, a rapid n-butyl chloride extraction of LSD from urine at pH 8 is followed by formation of the trimethylsilyl (TMS) derivative by treatment with N,O-bis(trimethylsilyl)trifluoroacetamide. The TMS derivative of LSD is identified and quantified by selected ion monitoring with a fused-silica capillary column and electron impact ionization. The procedure was used to monitor LSD concentrations in urine for eight hours following oral administration of 70.5 micrograms of LSD to two human volunteers. Concentrations of LSD determined by the assay are compared with concentrations determined by two other methods of analysis, a radioimmunoassay and a high-performance liquid chromatographic (HPLC) assay. Data concerning the stability of LSD in urine are also presented.

Clinical evaluation of a naltrexone sustained-release preparation

A clinical evaluation of the naltrexone bead, a biodegradable sustained-release dosage form of 3.0 mg in weight containing 70% naltrexone in a copolymer of lactic and glycolic acids, was carried out in 4 healthy normal males. Subjects were given an intravenous dose of 10 mg naltrexone and approx. 1 week later a 63-mg dose of naltrexone by subcutaneous administration of the beads. Challenge doses of 15 mg morphine were given to each subject during the study for the assessment of narcotic blockade effects of naltrexone. For a 2-4-week period after bead administration, relatively constant plasma levels were maintained at 0.30-0.46 ng/ml for naltrexone and were 0.64-1.07 ng/ml for naltrexol. Urine levels for unchanged and conjugated naltrexone were 79-215 ng/ml and for naltrexol were 315-500 ng/ml. From kinetic analysis, an average of 2.4-2.7% of implanted dose was absorbed each day from the administration of the beads. Opiate effects of morphine challenges were mitigated during the 2-4-week period after administration of naltrexone beads.

Pharmacokinetic interaction of propoxyphene with ethanol

In order to study the effects of ethanol on the pharmacokinetics of propoxyphene, six healthy male volunteers were each given (1) propoxyphene 65 mg p.o. preceded by 1 h by ethanol 0.9 g/kg lean body weight and followed for 7.5 h by ethanol dosed to maintain breath ethanol at 800-1000 mg/l; and (2) propoxyphene 65 mg p.o. with orange juice in the same volume and frequency as ethanol. Ethanol did not induce any significant changes in apparent t 1/2 or Cmax of propoxyphene or norpropoxyphene. The average norpropoxyphene/propoxyphene ratio decreased by a mean 36%.

Stability of delta 9-tetrahydrocannabinol (THC), 11-hydroxy-THC, and 11-nor-9-carboxy-THC in blood and plasma

The stabilities of delta 9-tetrahydrocannabinol (THC) and two of its metabolites, 11-hydroxy-delta 9-tetrahydrocannabinol (HO-THC) and 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (COOH-THC), were determined in blood and plasma stored at -10 degrees C, 4 degrees C, and room temperature. Each of the cannabinoids was added to freshly-drawn blood and plasma to give concentrations of 20 ng/mL. Two-mL aliquots were stored in silanized tubes and the cannabinoid concentrations were monitored by gas chromatography/mass spectrometry over a 6-month period. No significant changes were observed in the concentrations of the cannabinoids for the first month of storage. However, the concentrations of THC and HO-THC in blood stored at room temperature had decreased significantly at 2 months. No statistically significant changes were detected in cannabinoid concentrations in plasma or blood stored at 4 degrees or -10 degrees C for up to 4 months. After 6 months at room temperature, the blood concentrations of THC and HO-THC had decreased by 90 and 44%, respectively, whereas the concentration of COOH-THC was not significantly different from the control. The possibility of loss of cannabinoids from blood due to adsorption onto the grey stoppers used in Venoject tubes was also investigated. Over a 24-hr period, no significant differences were detected in any of the cannabinoid concentrations regardless of sample size (1.3 or 8 mL), differences in temperature (-10 degrees C, 4 degrees C, or room temperature), or extent of contact with the tube's stoppers.

Evaluation of immunoassays for cannabinoids in urine

A comparison was made of several cannabinoid urine assays. Two hundred randomly selected urine specimens were initially screened by two enzyme immunoassays (EMIT-st and EMIT-d.a.u.) and a radioimmunoassay (Abuscreen RIA). Selected specimens found positive by any of these methods were further analyzed by gas-liquid chromatography with flame ionization detection (GLC/FID), gas chromatography/mass spectrometry (GC/MS), and an experimental RIA from Research Triangle Institute (RTI RIA). The GLC/FID method gave confirmations in 69 to 92% of the samples, depending on the method used and the cut-off employed. GC/MS confirmed 98% of the EMIT and RIA positives using a low cut-off (20 ng/mL). All RIA positives at 100 ng/mL were confirmed by GC/MS. There was complete agreement between the RTI RIA and the EMIT assays, but not with the Abuscreen RIA at the 100 ng/mL cut-off. The study illustrates that care must be exercised in establishing assay cut-offs and the designation of false positive results.

Cannabinoid concentrations in plasma after passive inhalation of marijuana smoke

delta-9-tetrahydrocannabinol (THC) and its metabolite, 9-carboxy-THC, were detected in the plasma of a subject during a one-hour passive exposure to the smoke from four marijuana cigarettes containing a total of 104.8 mg of THC. Plasma concentrations of THC were determined by RIA and reached an apparent steady-state concentration of 2.2 ng/mL after 20 minutes of exposure. The presence of THC was confirmed by GC/MS analysis. Results from the two analyses exhibited excellent correlation (r = 0.990), although the concentrations determined by GC/MS were higher than those determined by RIA. Concentrations of 9-carboxy-THC were also determined by GC/MS, and remained consistently below the GC/MS determined concentrations of THC. By administering an infusion of THC, the dose that was inhaled and absorbed during the passive exposure was estimated to be 3.2 micrograms/min.