Broad spectrum drug identification directly from urine, using liquid chromatography-tandem mass spectrometry.
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BACKGROUND: Currently the rate-limiting step for mass spectrometric analysis of drugs in biological samples is sample preparation. Many gas chromatography/mass spectrometry (GC/MS) methods are specific for a certain class of compounds, requiring extraction and/or derivatization before analysis. The purpose of this study was to develop a broad spectrum liquid chromatography/mass spectrometry (LC/MS) procedure that allowed for direct analysis of urine specimens with potential for quantitative analysis. METHODS: We modified a commercially available column-switching instrument, the REMEDi HS from Bio-Rad Diagnostics, to make it compatible with atmospheric pressure ionization. The system we developed was based on electrospray ionization and used three LC columns to extract, purify, and separate drugs directly from urine specimens. Drugs and metabolites were tentatively identified on the basis of retention times and (M+H)(+) ions. Tandem mass spectrometry (MS/MS) was used to confirm the qualitative identification of suspected drugs, using data-dependent acquisition. For quantitative analysis, the cocaine metabolite benzoylecgonine was analyzed using isotope dilution and selected reaction monitoring. RESULTS: Seventeen basic drugs from a variety of classes of compounds were identified directly from urine without the need for prior sample extraction, using LC and MS/MS. Quantitative analysis was demonstrated for benzoylecgonine. When benzoylecgonine-d(3) was used as the internal standard, the method was linear from 30 to 10 000 microgram/L (range tested). At these concentrations, the within-run accuracy was +/- 10% of the target concentration, with CVs <10%. Analytical results by LC/MS/MS compared favorably with GC/MS values for 50 benzoylecgonine-containing specimens and for 25 negative specimens. CONCLUSIONS: The ability to directly analyze urine for a wide variety of drug classes, combined with the sensitivity and specificity of LC/MS/MS makes this technique attractive for many clinical, forensic, and biotechnology applications. (+info)
Cocaine pharmacokinetics in men and in women during the follicular and luteal phases of the menstrual cycle.
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Preclinical and clinical studies suggest that females may be less vulnerable to cocaine's toxic effects than males. The pharmacokinetics of intravenous cocaine (0.2 and 0.4 mg/kg) were measured in 12 men and 22 women with a history of cocaine abuse, matched with respect to age and body mass index (BMI). Women were studied during the follicular and the luteal phases of the menstrual cycle. There were no differences between men and women in pharmacokinetic measures [peak plasma cocaine levels (Cmax), elimination half-life (T 1/2 min), area under the curve (AUC)] or cardiovascular or subjective effects "high" measures. Heart rate increases were cocaine dose-related (p < .01-.02) and also did not differ between men and women. Cocaine's pharmacokinetic and pharmacodynamic effects were similar in men and women, and in women during the follicular and mid-luteal phases of the menstrual cycle. (+info)
Requirement of circadian genes for cocaine sensitization in Drosophila.
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The circadian clock consists of a feedback loop in which clock genes are rhythmically expressed, giving rise to cycling levels of RNA and proteins. Four of the five circadian genes identified to date influence responsiveness to freebase cocaine in the fruit fly, Drosophila melanogaster. Sensitization to repeated cocaine exposures, a phenomenon also seen in humans and animal models and associated with enhanced drug craving, is eliminated in flies mutant for period, clock, cycle, and doubletime, but not in flies lacking the gene timeless. Flies that do not sensitize owing to lack of these genes do not show the induction of tyrosine decarboxylase normally seen after cocaine exposure. These findings indicate unexpected roles for these genes in regulating cocaine sensitization and indicate that they function as regulators of tyrosine decarboxylase. (+info)
Cationic modulation of human dopamine transporter: dopamine uptake and inhibition of uptake.
(52/3711)
Effects of cations on dopamine (DA) uptake into cells expressing the human dopamine transporter and on inhibition of DA uptake by various substrates and inhibitors were investigated by using rotating disk electrode voltammetry. The Na(+) dependence of DA uptake varied with Na(+) substitutes, hyperbolic with Li(+), almost linear at 1 microM DA but hyperbolic at 8 microM DA with choline, and sigmoidal with K(+). With Na(+) substituted by Li(+), K([DA]) decreased and V(app) remained constant with increasing [Na(+)], whereas K([Na+]) decreased and V(app) increased with increasing [DA], suggesting an ordered sequence with Na(+) binding before DA. Similar trends for the Na(+)-DA interactions were observed in the presence of cocaine. Cocaine inhibited DA uptake solely by increasing K([DA]), with its K(i) not significantly different at 55 and 155 mM [Na(+)], whereas it inhibited Na(+) stimulation by reducing V(app) more than K([Na+]) at 1 microM DA, and V(app) only and less potently at 8 microM DA. Thus, cocaine may compete with DA, not with Na(+), for the transporter, and might not follow a strictly ordered reaction with Na(+). With Na(+) substituted by K(+), K([DA]) or K([Na+]) became insensitive to Na(+) or DA. K(+) impaired the DA uptake mainly by reducing V(app,) but affected cocaine inhibition by elevating K(i). Despite their different patterns for inhibiting DA uptake, nontransportable inhibitors cocaine, methylphenidate, mazindol, and 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenyl-2-propyl)piperazi ne (GBR12909) showed similarly modest Na(+) dependence in their K(i) values. In contrast, substrates DA, m-tyramine, and amphetamine displayed a similarly stronger Na(+) requirement for their apparent affinities. (+info)
Discriminative stimulus effects of morphine in squirrel monkeys: stimulants, opioids, and stimulant-opioid combinations.
(53/3711)
Morphine and other mu opioids mimic and/or modulate the discriminative stimulus (DS) effects of cocaine, possibly reflecting mutual stimulation of mesolimbic dopamine activity. Less is known about the capacity of cocaine and related stimulants to modulate the DS effects of morphine. The present study investigated the effects of cocaine, amphetamine, and reference drugs, administered alone and with morphine, in squirrel monkeys trained to discriminate morphine from vehicle. Additional studies determined the ability of opioid and dopamine receptor antagonists to attenuate the DS effects of morphine and the morphine-like effects of other drugs. The DS effects of morphine were mimicked by the mu-opioid agonist fentanyl but not the delta-opioid agonists SNC 80 and BW 373U86 or the kappa-opioid agonist U50,488H, and were antagonized by the opioid antagonist naltrexone but not the dopamine antagonist flupenthixol. In three of five monkeys, the DS effects of morphine also were mimicked by cocaine, amphetamine, and the dopamine transport inhibitor GBR 12909 but not the norepinephrine transport inhibitor talsupram or the serotonin transport inhibitor fluoxetine, and were antagonized by flupenthixol but not naltrexone. In this subgroup, pretreatment with cocaine or amphetamine enhanced the DS effects of morphine, whereas in the other two monkeys pretreatment with either stimulant attenuated the DS effects of morphine. The results demonstrated individual differences in morphine-like DS effects of stimulants that are mirrored by individual differences in their interactions with morphine. Furthermore, different mechanisms appear to mediate the DS effects of morphine and the morphine-like DS effects of cocaine and amphetamine. (+info)
Preclinical evaluation of newly approved and potential antiepileptic drugs against cocaine-induced seizures.
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Seizures and status epilepticus are among the neurological complications of cocaine overdose in humans. The aim of the present study was to evaluate the protective effectiveness and therapeutic index (separation between anticonvulsive and side effect profiles) of 14 newly approved and potential antiepileptic drugs using a murine model of acute cocaine toxicity and the inverted-screen test for behavioral side effect testing. Cocaine (75 mg/kg i.p.) produces clonic seizures (approximately 90% of mice), and conventional antiepileptic drugs have been reported to be either ineffective or only effective at doses producing significant sedative/ataxic effects. Clobazam, flunarizine, lamotrigine, topiramate, and zonisamide were ineffective against seizures up to doses producing significant motor impairment. In contrast, felbamate, gabapentin, loreclezole, losigamone, progabide, remacemide, stiripentol, tiagabine, and vigabatrin produced dose-dependent protection against cocaine-induced convulsions with varied separations between their anticonvulsant and side effect profiles: the protective index values (toxic TD(50)/anticonvulsive ED(50)) ranged from 1.26 (felbamate) to 7.67 (loreclezole), and gabapentin had the highest (protective index >152). Thus, several drugs were identified with greater protective efficacy and reduced motor impairment compared with classic antiepileptic drugs. Based on the proposed mechanism of action of these new anticonvulsants, it is noteworthy that 1) drugs that enhance gamma-aminobutyric acid-mediated neuronal inhibition in a manner distinct from barbiturates and benzodiazepines offer the best protective/behavioral side effect profiles, and 2) functional antagonists of Na(+) and Ca(2+) channels are generally ineffective. Overall, this study provides the first description of the effectiveness of new antiepileptic drugs against experimentally induced cocaine seizures and points to several drugs that deserve clinical scrutiny for this indication. (+info)
Effects of sex and gonadectomy on cocaine metabolism in the rat.
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The purpose of the current study is to determine whether sex differences in metabolism of cocaine (COC) exist that could contribute to the greater behavioral sensitivity of females to COC administration. To investigate this question, concentrations of COC and its two principle metabolites benzoylecgonine (BE) and ecgonine methyl ester (EME) were measured by gas chromatography/mass spectroscopy in brain and plasma collected from male and female rats that were sacrificed between 5 and 90 min after injection COC (15 mg/kg i.p.). COC concentrations did not differ in plasma or brain tissue of males and females, but sex-specific patterns of metabolite distribution were detected. BE was 2-fold higher in plasma and brain of males than females, whereas EME was much higher in brain and plasma of females. The influence of gonadal hormones on COC metabolite patterns were determined using gonadectomized and prepubertal rats. Castration of male or female rats did not alter brain or plasma COC, but did decrease BE concentrations. Seven-day-old pups injected with 15 mg/kg of COC had higher blood and brain COC than adults and relatively low levels of metabolites. No sex differences were found for COC, BE, or EME in brain or plasma of pups. These findings indicate that although gonadal steroids influence COC metabolism, these effects do not explain sex differences in COC-induced behaviors. (+info)
Cocaine-reinforced responding in rhesus monkeys: pharmacological attenuation of the hypothalamic-pituitary-adrenal axis response.
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Intravenously self-administered cocaine produces a dose-dependent release of adrenocorticotropic hormone (ACTH) and cortisol in male rhesus monkeys. This study investigated whether the acute disruption of cortisol and/or ACTH release had any effect on ongoing cocaine-maintained responding. Four hypothalamic-pituitary-adrenal (HPA) axis inhibitors were examined: etomidate and ketoconazole, both of which are cortisol synthesis inhibitors; astressin, a peptidic corticotropin-releasing factor (CRF) antagonist that binds CRF(1) receptors predominantly in the pituitary gland; and dexamethasone, a highly selective glucocorticoid receptor agonist whose long-lasting effects reduce or abolish the endogenous release of ACTH and cortisol. The reinforcing effects of a range of cocaine doses, with or without pretreatment with an HPA inhibitor, were evaluated using a fixed ratio 30 time-out 10-min schedule of reinforcement in six male monkeys. Blood was sampled before, during, and after self-administration sessions. Self-administration of cocaine increased plasma cortisol and ACTH. Pretreatment with etomidate and ketoconazole dose-dependently inhibited the cocaine-induced rise in cortisol and, at the highest doses, produced a compensatory increase in ACTH release. Astressin and dexamethasone attenuated or abolished cocaine-induced cortisol and ACTH release. Despite the efficacy exhibited by these pretreatments and the variety of mechanisms by which they inhibited the HPA axis, there was no evidence for any change in cocaine-reinforced behavior (response rate or infusion number), an indication that acute changes in the ACTH or cortisol response to cocaine do not play a direct role in modulating cocaine-seeking behavior under these behavioral circumstances. (+info)