The role of the serotonergic system in atropine's anti-myopic effects.

The muscarinic cholinergic antagonist atropine is the most widely used pharmacological treatment for the visual disorder myopia (short-sightedness), the leading cause of low-vision worldwide. This study sought to better define the mechanism by which atropine inhibits myopic growth. Although classified as a muscarinic-cholinergic antagonist, atropine has been found to bind and modulate the activity of several non-cholinergic systems (e.g., serotonin). Thus, this study investigated whether the serotonergic system could underly atropine's anti-myopic effects. Using a chick model of myopia, we report that atropine's growth-inhibitory effects can be attenuated by pharmacological stimulation of the serotonin system. This may suggest that atropine can slow the development of myopia through inhibiting serotonergic receptor activity. We also observed that pharmacological antagonism of serotonergic receptors inhibits the development of experimental myopia in a dose-dependent manner, further demonstrating that modulation of serotonergic receptor activity can alter ocular growth rates. Finally, we found that neither experimental myopia, nor atropine treatment, induced a significant change in retinal serotonergic output (i.e., synthesis, transport, release and catabolism). This may suggest that, although myopic growth can be inhibited through modulation of serotonergic receptor activity (by atropine or serotonergic antagonists), this does not require a change in serotonin levels. These findings regarding a serotonergic mechanism for atropine may have significant ramifications for the treatment of human myopia. This includes assessing the use of atropine in patients who are also undergoing treatment to upregulate serotonergic signaling (e.g., serotonergic anti-depressants).

Insights into the mechanism by which atropine inhibits myopia: evidence against cholinergic hyperactivity and modulation of dopamine release.

BACKGROUND AND PURPOSE: The ability of the muscarinic cholinergic antagonist atropine to inhibit myopia development in humans and animal models would suggest that cholinergic hyperactivity may underlie myopic growth. To test this, we investigated whether cholinergic agonists accelerate ocular growth rates in chickens. Furthermore, we investigated whether atropine alters ocular growth by downstream modulation of dopamine levels, a mechanism postulated to underlie its antimyopic effects. EXPERIMENTAL APPROACH: Muscarinic (muscarine and pilocarpine), nicotinic (nicotine) and non-specific (oxotremorine and carbachol) cholinergic agonists were administered to chicks developing form-deprivation myopia (FDM) or chicks that were otherwise untreated. Vitreal levels of dopamine and its primary metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) were examined using mass spectrometry MS in form-deprived chicks treated with atropine (360, 15 or 0.15 nmol). Further, we investigated whether dopamine antagonists block atropine's antimyopic effects. KEY RESULTS: Unexpectedly, administration of each cholinergic agonist inhibited FDM but did not affect normal ocular development. Atropine only affected dopamine and DOPAC levels at its highest dose. Dopamine antagonists did not alter the antimyopia effects of atropine. CONCLUSION AND IMPLICATIONS: Muscarinic, nicotinic and non-specific cholinergic agonists inhibited FDM development. This indicates that cholinergic hyperactivity does not underlie myopic growth and questions whether atropine inhibits myopia via cholinergic antagonism. This study also demonstrates that changes in retinal dopamine release are not required for atropine's antimyopic effects. Finally, nicotinic agonists may represent a novel and more targeted approach for the cholinergic control of myopia as they are unlikely to cause the anterior segment side effects associated with muscarinic treatment.

Coadministration With Carbidopa Enhances the Antimyopic Effects of Levodopa in Chickens.

Purpose: Topical application of levodopa inhibits the development of form-deprivation myopia (FDM) and lens-induced myopia (LIM) in chicks. Here we examine whether coadministration with carbidopa enhances this protection and compare the effectiveness of topical versus systemic administration. We also investigate the degree to which topical and systemic administration of these compounds alters retinal dopamine release and examine whether this is the mechanism by which they inhibit experimental myopia. Methods: Levodopa and levodopa:carbidopa (at a 4:1 ratio) were administered as twice-daily eye drops or once-daily intraperitoneal injections to chicks developing FDM or LIM over an ascending dose range. Axial length and refraction were measured following 4 days of treatment. Dopamine levels in the vitreous and blood were analyzed using liquid chromatography-mass spectrometry following topical or systemic administration of levodopa or levodopa:carbidopa. Finally, chicks receiving topical or systemic levodopa or levodopa:carbidopa were cotreated with the dopamine antagonist spiperone. Results: Levodopa:carbidopa inhibited the development of FDM and LIM to a greater extent than levodopa alone (P < 0.05). Topical application was more effective than systemic administration (P < 0.001). Vitreal dopamine levels were increased to the greatest extent by topical application of levodopa:carbidopa (P < 0.001). Systemic but not topical administration significantly increased dopamine levels within the blood (P < 0.01). Cotreatment with spiperone inhibited the antimyopic effects (P < 0.05) of levodopa and levodopa:carbidopa. Conclusions: The presence of carbidopa increases the bioavailability of levodopa within the eye, enhancing its antimyopic effects, with topical application showing the greatest efficacy. Thus levodopa:carbidopa may be a promising treatment for controlling the progression of human myopia.

Effectiveness and safety of topical levodopa in a chick model of myopia.

Animal models have demonstrated a link between dysregulation of the retinal dopamine system and the excessive ocular growth associated with the development of myopia. Here we show that intravitreal or topical application of levodopa, which is widely used in the treatment of neurological disorders involving dysregulation of the dopaminergic system, inhibits the development of experimental myopia in chickens. Levodopa slows ocular growth in a dose dependent manner in chicks with a similar potency to atropine, a common inhibitor of ocular growth in humans. Topical levodopa remains effective over chronic treatment periods, with its effectiveness enhanced by coadministration with carbidopa to prevent its premature metabolism. No changes in normal ocular development (biometry and refraction), retinal health (histology), or intraocular pressure were observed in response to chronic treatment (4 weeks). With a focus on possible clinical use in humans, translation of these avian safety findings to a mammalian model (mouse) illustrate that chronic levodopa treatment (9 months) does not induce any observable changes in visual function (electroretinogram recordings), ocular development, and retinal health, suggesting that levodopa may have potential as a therapeutic intervention for human myopia.

An empirical review of antimalarial quality field surveys: the importance of characterising outcomes.

For decades, thousands of people have been dying from malaria infections because of poor-quality medicines (PQMs). While numerous efforts have been initiated to reduce their presence, PQMs are still risking the lives of those seeking treatment. This review addresses the importance of characterising results of antimalarial medicine field surveys based upon the agreement of clearly defined definitions. Medicines found to be of poor quality can be falsified or counterfeit, substandard or degraded. The distinction between these categories is important as each category requires a different countermeasure. To observe the current trends in the reporting of field surveys, a systematic literature search of six academic databases resulted in the quantitative analysis of 61 full-text journal articles. Information including sample size, sampling method, geographical regions, analytical techniques, and characterisation conclusions was observed for each. The lack of an accepted uniform reporting system has resulted in varying, incomplete reports, which may not include important information that helps form effective countermeasures. The programmes influencing medicine quality such as prequalification, procurement services, awareness and education can be supported with the information derived from characterised results. The implementation of checklists such as the Medicine Quality Assessment Reporting Guidelines will further strengthen the battle against poor-quality antimalarials.

Bioaccessibility and degradation of naturally occurring arsenic species from food in the human gastrointestinal tract.

Humans are exposed to organic arsenic species through their diet and therefore, are susceptible to arsenic toxicity. Investigating the transformations occurring in the gastrointestinal tract will influence which arsenic species to focus on when studying metabolism in cells. Using a physiologically based extraction test, the bioaccessibility of arsenic species was determined after the simulated gastrointestinal digestion of rice, seaweed and fish. Pure standards of the major arsenic species present in these foodstuffs (arsenic glutathione complexes, arsenosugars and short chain fatty acids) were also evaluated to assess the effect of the food matrix on bioaccessibility and transformation. Approximately 80% of arsenic is released from these foodstuffs, potentially becoming available. Hydrolysis and demethylation of arsenic glutathione complexes and arsenosugars standards was observed, but no transformations occurred to arsenosugars present in seaweed. Demethylation of MA and DMA from rice occurs increasing the amount of inorganic arsenic species available for metabolism.

Evaluation of the ability of arsenic species to traverse cell membranes by simple diffusion using octanol-water and liposome-water partition coefficients.

Arsenic metabolism in living organisms is dependent on the ability of different arsenic species to traverse biological membranes. Simple diffusion provides an alternative influx and efflux route to mediated transport mechanisms that can increase the amount of arsenic available for metabolism in cells. Using octanol-water and liposome-water partition coefficients, the ability of arsenous acid, arsenate, methylarsonate, dimethylarsinate, thio-methylarsonate, thio-dimethylarsinic acid, arsenotriglutathione and monomethylarsonic diglutathione to diffuse through the lipid bilayer of cell membranes was investigated. Molecular modelling of arsenic species was used to explain the results. All arsenic species with the exception of arsenate, methylarsonate and thio-methylarsonate were able to diffuse through the lipid bilayer of liposomes, with liposome-water partition coefficients between 0.04 and 0.13. Trivalent arsenic species and thio-pentavalent arsenic species showed higher partition coefficients, suggesting that they can easily traverse cell membranes by passive simple diffusion. Given the higher toxicity of these species compared to oxo-pentavalent arsenic species, this study provides evidence supporting the risk associated with human exposure to trivalent and thio-arsenic species.

Qualitative analysis of seized cocaine samples using desorption electrospray ionization- mass spectrometry (DESI-MS).

Desorption electrospray ionization - mass spectrometry (DESI-MS) is a useful technique for the qualitative analysis of compounds found in seized drug material. In this study, DESI-MS was utilized in the screening analysis of illicit cocaine samples. The technique was also applied to the geographical origin determination of these samples. The limit of detection was determined to be 24.3 µg (or 3.47 µg/mm(2) ) and the analysis time was less than 1 minute per sample. The intra-day and inter-day precision for the detection of cocaine was 11 % and 42 %, respectively; therefore the quantitative data provided by DESI-MS was limited in its use for accurate determination of cocaine concentration in a sample. Using the quadrupole time-of-flight (QTOF) mass spectrometer, the presence of cocaine and impurities detected were confirmed by accurate tandem MS data. The qualitative chemical profiles obtained using DESI-MS were compared to two popular analysis techniques, GC-MS and LC-MS. The effects of a range of adulterants including caffeine, procaine, levamisole, lignocaine, paracetamol, and atropine on the detectability of cocaine were also investigated. It was found that the addition of these adulterants in a cocaine sample did not prevent the detection of the analyte itself (there was slight enhancement in some samples), which was useful in drug detection. The detection of truxillines in the seized samples by DESI-MS aided in the preliminary determination of geographical origin, i.e., Bolivian, Peruvian or Colombian leaf origin. The application of DESI-MS to the qualitative analysis and screening of seized cocaine samples demonstrates the potential and applicability of the technique to the fast chemical profiling of illicit samples.

Analysis of amphetamine-type substances and piperazine analogues using desorption electrospray ionisation mass spectrometry.

RATIONALE: Although amphetamine-type substances (ATS) have been investigated extensively in recent years, scarce data is available on screening tests for piperazine analogues. The need for a universal technique capable of detecting an extensive range of drug compounds becomes increasingly important with the continued emergence of novel drug analogues. METHODS: Desorption electrospray ionisation mass spectrometry (DESI-MS) is a technique that allows examination of compounds in drug materials directly from ambient surfaces. In this study, DESI-MS was utilised in the analysis of ATS including amphetamine (AP), methylamphetamine (MA), 3,4-methylenedioxymethylamphetamine (MDMA), N,N-dimethylamphetamine (DMA), 4-methoxyamphetamine (PMA) and 4-methoxymethylamphetamine (PMMA), and piperazine analogues including 1-benzylpiperazine (BZP), 1-[3-(trifluoromethyl)phenyl]piperazine (TFMPP), 1-(3-chlorophenyl)piperazine (mCPP) and 1-(4-methoxyphenyl)piperazine (MeOPP). Semi-porous polytetrafluoroethylene (PTFE or Teflon) sheets welled with a 3 mm hole punch were used to contain the 2 µL liquid sample (spot size 7 mm(2) ). RESULTS: The limits of detection (LODs) of these compounds using DESI-MS were determined to be in the range 0.02-2.80 µg/mm(2) . The intra-day and inter-day precision of the technique were <25% and <33%, respectively. DESI-MS was successful in determining the compound of interest and reaction by-products and impurities in the samples tested (such as 1,4-dibenzylpiperazine in BZP samples) with the exception of those present in trace amounts. The effects of common adulterants on the detectability of MA were evaluated. The addition of magnesium stearate to MA significantly enhanced the signal response. CONCLUSIONS: This work has demonstrated the applicability of DESI-MS in the screening and profiling of MDMA, PMMA, BZP, TFMPP, mCPP, MeOPP as well as other complex mixtures.

Determining the effects of routine fingermark detection techniques on the subsequent recovery and analysis of explosive residues on various substrates.

An offender who has recently handled bulk explosives would be expected to deposit latent fingermarks that are contaminated with explosive residues. However, fingermark detection techniques need to be applied in order for these fingermarks to be detected and recorded. Little information is available in terms of how routine fingermark detection methods impact on the subsequent recovery and analysis of any explosive residues that may be present. If an identifiable fingermark is obtained and that fingermark is found to be contaminated with a particular explosive then that may be crucial evidence in a criminal investigation (including acts of terrorism involving improvised explosive devices). The principal aims of this project were to investigate: (i) the typical quantities of explosive material deposited in fingermarks by someone who has recently handled bulk explosives; and (ii) the effects of routine fingermark detection methods on the subsequent recovery and analysis of explosive residues in such fingermarks. Four common substrates were studied: paper, glass, plastic (polyethylene plastic bags), and metal (aluminium foil). The target explosive compounds were 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), as well as chlorate and nitrate ions. Recommendations are provided in terms of the application of fingermark detection methods on surfaces that may contain explosive residues.

A review of impurity profiling and synthetic route of manufacture of methylamphetamine, 3,4-methylenedioxymethylamphetamine, amphetamine, dimethylamphetamine and p-methoxyamphetamine.

Amphetamine-type substances (ATS), like other synthetically derived compounds, can be produced by a multitude of synthetic pathways using a variety of precursors and reagents, resulting in a large number of possible contaminants (by-products, intermediates and impurities). This review article describes the common contaminants found in preparations of methylamphetamine (MA), 3,4-methylenedioxymethylamphetamine (MDMA), amphetamine (AP), N,N-dimethylamphetamine (DMA) and p-methoxyamphetamine (PMA) synthesised via common synthetic pathways including reductive amination, Leuckart method, Nagai method, Emde method, Birch reduction, "Moscow" method, Wacker process, "Nitrostyrene" method and the Peracid oxidation method. Contaminants can facilitate identification of the synthetic route, origin of precursors and may suggest information as to the location of manufacture of these illicit drugs. Contaminant profiling can provide vital intelligence for investigations in which linking seizures or identifying the synthetic pathway is essential. This review article presents an accessible resource; a compilation of contaminants resulting from a variety of manufacturing methods used to synthesise the most common ATS. It is important for research in this field to continue as valuable information can be extracted from illicit drug samples, increasing discrimination amongst ATS, and in turn, leading to an increase in evidential value and forensic drug intelligence from forensic drug samples.

Pharmacokinetics of cocaine and metabolites in human oral fluid and correlation with plasma concentrations after controlled administration.

UNLABELLED: Oral fluid is an attractive alternative matrix for drug testing with a noninvasive and directly observed collection, but there are few controlled cocaine administration studies to guide interpretation. MATERIALS AND METHODS: While residing on a closed research unit for up to 10 weeks under constant medical supervision, 19 participants were administered 75 mg/70 kg subcutaneous cocaine and 14 received 150 mg/70 kg. The disposition of cocaine, benzoylecgonine (BE), and ecgonine methyl ester (EME) into oral fluid was determined by gas chromatography-mass spectrometry for 0.08 to 48 hours after administration. RESULTS: In oral fluid collected by citric acid candy-stimulated expectoration, cocaine first appeared in oral fluid 0.08 to 0.32 hours after dosing and was rapidly eliminated with half-lives of 1.1 to 3.8 hours. BE and EME were first detected 0.08 to 1.0 hours after dosing with longer half-lives of 3.4 to 13.8 (BE) and 2.4 to 15.5 hours (EME) (P < 0.05). Oral fluid and plasma concentrations were significantly correlated for cocaine, BE, and EME (P < 0.0001). There were no significant differences (P > 0.05) in first and last detection times with the 8-µg/L cutoff proposed by the Substance Abuse and Mental Health Services Administration or the 10-µg/L cutoff from the European initiative, Driving Under the Influence of Drugs, Alcohol and Medicines. Metabolite:cocaine ratios increased after cocaine administration, potentially helpful for interpreting time of last use. Comparison of oral fluid collection through citric acid candy-stimulated expectoration, citric acid-treated Salivette, and neutral cotton Salivette devices did not reveal significant differences between devices for areas under the curve for cocaine, BE, or EME (P > 0.05). DISCUSSION AND CONCLUSION: These results provide additional evidence for interpreting cocaine and metabolite concentrations in oral fluid and oral fluid's usefulness as an alternative matrix for drug testing.

New meconium biomarkers of prenatal methamphetamine exposure increase identification of affected neonates.

BACKGROUND: Prenatal methamphetamine (MAMP) exposure is poorly reflected in neonatal meconium. Often, maternal self-reported MAMP use is not corroborated by positive results in amphetamines immunoassays of meconium, and even if initial test results are positive, they frequently are not confirmed for MAMP or amphetamine (AMP) by chromatographic analysis. The presence of the MAMP metabolites p-hydroxymethamphetamine (pOHMAMP), p-hydroxyamphetamine (pOHAMP), and norephedrine (NOREPH) in meconium may improve the identification of MAMP- and AMP-exposed neonates. METHODS: Immunoassay-positive and -negative meconium samples were subjected to liquid chromatography- tandem mass spectrometric reanalysis for these recently identified metabolites. RESULTS: pOHAMP and NOREPH were detected only when MAMP and/or AMP were present and thus do not appear to be promising biomarkers of prenatal MAMP exposure. pOHMAMP, in contrast, identified 6 additional neonates whose mothers reported MAMP exposure, yet had a meconium sample screened as negative; pOHMAMP was more likely to be present if maternal MAMP use continued into the third trimester. Although the pOHMAMP results for meconium samples corroborated the maternal self-reports, the confirmation rate for positive meconium screening results did not improve with the inclusion of these new biomarkers. CONCLUSIONS: pOHMAMP identified additional MAMP- exposed neonates; therefore, MAMP, AMP, and pOHMAMP should be included in meconium chromatographic analyses. Maximizing the identification of MAMP-exposed children requires improvement in immunoassay screening tests to reduce false-negative and false-positive results. Additional research will help clarify which AMP-related compounds, if any, contribute to unconfirmed positive results in screening tests. Furthermore, nonamphetamine compounds endogenous to the complex meconium matrix also may cross-react, making chromatographic confirmation of screening results essential.

Novel biomarkers of prenatal methamphetamine exposure in human meconium.

Meconium analysis can detect fetal exposure to drugs taken by the mother during pregnancy. Methamphetamine (MAMP) and amphetamine (AMP) have previously been observed in meconium of MAMP-exposed neonates; the presence of other metabolites has not been investigated. Detection of such analytes may lead to more sensitive identification and thus improved medical treatment of affected infants. Forty-three MAMP-positive meconium specimens were analyzed for newly identified MAMP biomarkers, p-hydroxymethamphetamine, p-hydroxyamphetamine, and norephedrine. Due to MAMP adulteration in illicit ecstasy and to simultaneously monitor 3,4-methylenedioxymethamphetamine and MAMP prenatal exposure, 3,4-methylenedioxymethamphetamine, its metabolites, and related sympathomimetic amines were assayed. MAMP, AMP, and unconjugated p-hydroxymethamphetamine were the most prevalent and abundant analytes present in meconium; however, unconjugated p-hydroxyamphetamine and norephedrine also were identified. It is possible that one of these additional analytes could be important for predicting toxicity or maternal or neonatal outcome measures in fetuses exposed to MAMP at specific gestational ages or with different metabolic capabilities. Although these new biomarkers were present in lower concentrations than MAMP and AMP in the meconium of previously confirmed specimens, additional research will determine if inclusion of these analytes can increase identification of MAMP-exposed neonates. Novel methamphetamine biomarker concentrations were characterized in meconium of infants exposed in utero to MAMP.

Development and validation of a liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry method for simultaneous analysis of 10 amphetamine-, methamphetamine- and 3,4-methylenedioxymethamphetamine-related (MDMA) analytes in human meconium.

A liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (LC-APCI-MS/MS) method for quantification of 10 amphetamine-related analytes in 1g meconium is presented. Specimen preparation included homogenization and solid-phase extraction. Two multiple reaction monitoring transitions were monitored per analyte. Ten and 1 microL injection volumes permitted quantification up to 10,000 ng/g, with sufficient sensitivity to quantify minor metabolites. Lower limits of quantification ranged from 1.25 to 40 ng/g. Precision was less than 14.2%, with accuracy between 79 and 115%. Meconium from a methamphetamine-exposed neonate was analyzed. Metabolites p-hydroxymethamphetamine, norephedrine and 4-hydroxy-3-methoxymethamphetamine were identified in meconium for the first time.

A fast CE method for the achiral separation of methadone and its major metabolites, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine and 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline.

The utilization of dynamic doubly coated capillaries for a fast separation of methadone and its two major metabolites, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline (EMDP) was investigated. The coated capillaries were prepared using a polycation of poly(diallyldimethylammonium chloride) and a polyanion of dextran sulfate. A fast achiral separation was developed using the coated capillaries with a BGE of 100 mM phosphate buffer at pH 2.6. Complete achiral separation of methadone, EDDP and EMDP was achieved, with migration times of approximately 4 min. The method offers considerable advantages with respect to BGE simplicity and analysis time compared to previously published CE methods for methadone and its related analytes.

Chiral analysis of methadone and its major metabolites (EDDP and EMDP) by liquid chromatography-mass spectrometry.

Racemic methadone (MET) is administered to heroin users undergoing methadone maintenance therapy (MMT) in Australia. The enantiomers of methadone possess different pharmacological effects, and the enantioselective metabolism of methadone to its two major metabolites, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline (EMDP) has been demonstrated. Therefore, a stereoselective method capable of quantifying methadone, EDDP and EMDP in biological samples could be of benefit in the monitoring of MMT patients. In particular, the analysis of hair samples would provide a means by which long-term monitoring of MMT patients could be achieved. To date, no HPLC method has been published for the simultaneous separation of the six enantiomers. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the chiral analysis of methadone, EDDP and EMDP was developed using an alpha-glycoprotein (AGP) stationary phase. The method development involved the utilisation of factorial analysis experimental designs and the application of artificial neural networks (ANNs) to model the chromatographic response surfaces. The optimal conditions were determined to be 20mM acetic acid: isopropanol (93:7, pH 7.4), with a flow rate of 0.9mL/min. The method was validated and subsequently applied to the analysis of 20 hair samples collected from MMT patients.

Chiral separation of methadone, 2-ethylidene- 1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline (EMDP) by capillary electrophoresis using cyclodextrin derivatives.

A stereoselective method was developed for the simultaneous determination of methadone and its two major metabolites, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline (EMDP) by capillary electrophoresis. Five beta-cyclodextrin (betaCD) background electrolyte (BGE) additives were evaluated for resolution efficiency. The conditions for baseline resolution of each of the three enantiomer pairs was determined to be 1 mM heptakis-(2,6-di-O-methyl)-beta-cyclodextrin (DMbetaCD) in 100 mM phosphate at pH 2.6. This method represents the first successful method for the resolution of the six enantiomers associated with the metabolism of methadone. The utilisation of doubly coated capillaries in conjunction with betaCD derivatives for a faster separation of the methadone-related enantiomers is also reported. The coated capillaries were prepared using a polycation of poly(diallyldimethylammonium chloride) (PDDAC) and a polyanion of dextran sulfate. Baseline resolution of the methadone enantiomers was achieved with a BGE of 8 mM (2-hydroxy)propyl-beta-cyclodextrin (HPbetaCD) in 100 mM phosphate at pH 2.6. The migration times for the stereoselective methadone separation were approximately 4 min, which represented a reduction by a factor of approximately three, compared to that attained using analogous conditions with the uncoated capillary.

A rapid and sensitive high-performance liquid chromatography-electrospray ionization-triple quadrupole mass spectrometry method for the quantitation of oxycodone in human plasma.

A sensitive method for the determination of oxycodone concentrations in plasma by high-performance liquid chromatography (HPLC)-electrospray ionization-triple quadrupole mass spectrometry is described. The method is rugged, reliable, selective, and rapid with a run time of 2 min. One milliliter of plasma is made basic and extracted with 2-mL duplicate portions of 2% isoamyl alcohol in n-butyl chloride. The combined extracts are then evaporated to dryness, reconstituted in 100 microL of the mobile phase (15% methanol-85% water containing 0.1% acetic acid), and injected onto the HPLC. The limit of quantitation is 1 ng/mL, and the estimated limit of detection is 33 pg/mL (signal-to-noise = 3). Standard curves are linear over the range of 1 to 100 ng/mL with all correlation coefficient values greater than 0.9989. The method is used to determine the concentration of oxycodone in human plasma following the intravenous infusion of doses ranging from 5 to 15 mg in which the analysis of over 3000 plasma samples is required.