Overlooked Scents: Chemical Profile of Soma, Volatile Emissions and Trails of the Green Tree Ant, Oecophylla smaragdina.

The green tree ant, Oecophylla smaragdina, is one of only two recognized species of weaver ants. While the identity and functions of chemicals produced and emitted by its congener O. longinoda have been studied quite extensively and serve as a valuable model in chemical ecology research, little comparable information is available about O. smaragdina. Although some analyses of chemicals produced and emitted by O. smaragdina have been reported, the literature is fragmentary and incomplete for this species. To address this knowledge gap, and to enable comparisons in the chemical ecology of the two weaver ant species, we here describe diverse chemicals from the cuticle, Dufour's glands, poison glands, head, headspace volatiles, and trails of O. smaragdina.

Simultaneous determination of carisoprodol and aspirin in human plasma using liquid chromatography-tandem mass spectrometry in polarity switch mode: application to a human pharmacokinetic study.

A simple, sensitive and rapid LC-MS/MS-ESI method has been developed and validated for simultaneous quantification of the carisoprodol and aspirin in human plasma. Carisoprodol was detected in positive ion mode, whereas aspirin was detected in negative ion mode. Carbamazepine and furosemide were used as internal standards (IS) for quantification of carisoprodol and aspirin, respectively. The extraction procedure involves a liquid-liquid extraction method with ter-butyl methyl ether. Chromatographic separation was achieved on a Zorbax XDB-Phenyl (4.6 × 75 mm, 3.5 µm) column using an isocratic mobile phase (5 mm ammonium acetate:methanol, 20:80, v/v) at a flow rate of 0.8 mL/min with a total run time of 2.2 min. A detailed method validation was performed as per the FDA guidelines. The standard curves found to be linear in the range of 25.5-4900 and 15.3-3000 ng/mL for carisoprodol and aspirin, respectively. The results met the acceptance criteria. Carisoprodol and aspirin were found to be stable in various stability studies. The validated method was successfully applied to a pharmacokinetic study following co-administration of carisoprodol (250 mg) and aspirin (75 mg) tablets by oral route to human volunteers.

A rapid quantitative method of carisoprodol and meprobamate by liquid chromatography-tandem mass spectrometry.

The identification and quantitation of carisoprodol (Soma) and its chief metabolite meprobamate, which is also a clinically prescribed drug, remains a challenge for forensic toxicology laboratories. Carisoprodol and meprobamate are notable for their widespread use as muscle relaxants and their frequent identification in the blood of impaired drivers. Routine screening is possible in both an acidic/neutral pH screen and a traditional basic screen. An improvement in directed testing quantitations was desirable over the current options of an underivatized acidic/neutral extraction or a basic screen, neither of which used ideal internal standards. A new method was developed that utilized a simple protein precipitation, deuterated internal standards and a short 2-min isocratic liquid chromatography separation, followed by multiple reaction monitoring with tandem mass spectrometry. The linear quantitative range for carisoprodol was determined to be 1-35mg/L and for meprobamate was 0.5-50mg/L. The method was validated for specificity and selectivity, matrix effects, and accuracy and precision.

Validation of a new homogeneous immunoassay for the detection of carisoprodol in urine.

The objective of this project was to validate a new high-throughput homogeneous enzyme immunoassay (HEIA) for the rapid detection of carisoprodol in human urine. Carisoprodol (Soma(®)) and meprobamate are widely prescribed as musculoskeletal pain relief drugs and are listed as one of the 10 most frequently identified drugs associated with DUI cases. Carisoprodol has a short elimination half-life of 1-3 h; however, its major active metabolite, meprobamate, has a longer elimination half-life of 6-17 h. As a result, it is important for an immunoassay to cross-react with both compounds. The advantage of this new assay is that cutoff concentrations can be adjusted between 100 and 500 ng/mL. The reportable range was 25 to 1000 ng/mL for carisoprodol and 50 to 10,000 ng/mL for meprobamate. The intraday coefficient of variation (% CV) for the semi-quantitative assay was less than 1%. The homogeneous assay was validated with a total of 86 urine samples previously analyzed by liquid chromatography-tandem mass spectrometry with carisoprodol concentrations ranging from 50 to 10,000 ng/mL. The accuracy was found to be 100% when immunoassay cutoff concentrations of carisoprodol and meprobamate were set at 100 and 1000 ng/mL, respectively.

Rapid and sensitive LC-MS/MS method for determination of felbamate in mouse plasma and tissues and human plasma.

Felbamate (2-phenyl-1,3-propanediol dicarbamate) is a second generation antiepileptic drug used to treat seizures refractory to other antiepileptic drugs. With approximately 3500 new patients exposed annually, several important pharmacologic interaction questions remain unanswered necessitating the need for rapid and accurate methods of felbamate analysis in biological matrices. To this end, a rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the measurement of felbamate in mouse plasma and tissues and human plasma. Plasma (100 µL) and tissues homogenates (100 µL of 100 mg/mL) were spiked with internal standard (carisoprodol) prior to protein precipitation with acetonitrile. Samples were chromatographed on a XBridge Phenyl, 2.5 µm, 4.6 mm×50 mm column with quantitation by internal standard reference monitoring of the ion transitions m/z 239→117 for felbamate and m/z 261→176 for carisoprodol. Calibration curves were linear from 2.5 to 500 ng/mL in mouse or human plasma and 25-5000 pg/mg in tissue homogenates. Recoveries were greater than 97% for plasma and homogenates with accuracies >92% in any of the mouse matrices and >88% in human plasma. Comparable accuracies and precision were found with and without the use of the internal standard in preparation of the calibration curves and suggest that the internal standard may not be required.

Quantitative analysis of carisoprodol and meprobamate in whole blood using benzylcarbamate and deuterated meprobamate as internal standards.

Carisoprodol and meprobamate are frequently encountered drugs in impaired driving casework. Deuterated internal standards, although preferred, were not available until recently. Earlier published studies report the use of a variety of non-deuterated internal standards, many of which lack the chemical and physical similarities that are desired for quantitative analysis. Carisoprodol and meprobamate were determined in whole blood using solid-phase extraction and gas chromatography-mass spectrometry with benzylcarbamate and meprobamate-d(7) as internal standards. When benzylcarbamate was used as internal standard, the linear ranges for carisoprodol and meprobamate were 0-20 mg/L and 0-40 mg/L, respectively. The linear range increased to 100 mg/L when meprobamate-d(7) was used. Limits of detection for carisoprodol and meprobamate were 0.2 and 0.4 mg/L, respectively, regardless of the internal standard selection. The limit of quantitation for both drugs using either internal standard was 0.4 mg/L. Accuracies using benzylcarbamate and meprobamate-d(7) were 100-106% and 91-100%, respectively. Corresponding values for precision indicated intra-assay coefficients of variation of 2.6-4.3% for benzylcarbamate and 1.0-2.3% for meprobamate-d(7). No carryover was evident at 100 mg/L, the highest concentration tested, and no interferences were observed. Results indicated that either benzylcarbamate or meprobamate-d(7) is a suitable internal standard for quantitative determination of carisoprodol or meprobamate from whole blood.

Carisoprodol-mediated modulation of GABAA receptors: in vitro and in vivo studies.

Carisoprodol is a frequently prescribed muscle relaxant. In recent years, this drug has been increasingly abused. The effects of carisoprodol have been attributed to its metabolite, meprobamate, a controlled substance that produces sedation via GABA(A) receptors (GABA(A)Rs). Given the structural similarities between carisoprodol and meprobamate, we used electrophysiological and behavioral approaches to investigate whether carisoprodol directly affects GABA(A)R function. In whole-cell patch-clamp studies, carisoprodol allosterically modulated and directly activated human alpha1beta2gamma2 GABA(A)R function in a barbiturate-like manner. At millimolar concentrations, inhibitory effects were apparent. Similar allosteric effects were not observed for homomeric rho1 GABA or glycine alpha1 receptors. In the absence of GABA, carisoprodol produced picrotoxin-sensitive, inward currents that were significantly larger than those produced by meprobamate, suggesting carisoprodol may directly produce GABAergic effects in vivo. When administered to mice via intraperitoneal or oral routes, carisoprodol elicited locomotor depression within 8 to 12 min after injection. Intraperitoneal administration of meprobamate depressed locomotor activity in the same time frame. In drug discrimination studies with carisoprodol-trained rats, the GABAergic ligands pentobarbital, chlordiazepoxide, and meprobamate each substituted for carisoprodol in a dose-dependent manner. In accordance with findings in vitro, the discriminative stimulus effects of carisoprodol were antagonized by a barbiturate antagonist, bemegride, but not by the benzodiazepine site antagonist, flumazenil. The results of our studies in vivo and in vitro collectively suggest the barbiturate-like effects of carisoprodol may not be due solely to its metabolite, meprobamate. Furthermore, the functional traits we have identified probably contribute to the abuse potential of carisoprodol.

Simultaneous determination of carisoprodol and meprobamate in human hair using solid-phase extraction and gas chromatography/mass spectrometry of the trimethylsilyl derivatives.

Carisoprodol (CSP) is a musculoskeletal relaxant whose active metabolite is meprobamate (MPB). This drug has recently been noticed to be abused as an inexpensive alternative to illicit drugs in Korea. A method using solid-phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) was developed for the determination of CSP and MPB in human hair. Hair samples (30 mg) were washed with distilled water and acetone, cut into small fragments (<1 mm), incubated in 1.0 M HCl overnight at 50 degrees C, and then adjusted to pH 6.5. The drugs were extracted from the resulting hydrolyzed solutions using a SPE column. The eluents were evaporated to dryness, then derivatized using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS) at 120 degrees C for 30 min. The derivatized extract (1 microL) was injected into the GC/MS system. Recoveries were in the range of 91.5-93.1% for CSP and 85.5-93.0% for MPB. The linear ranges were 0.5-10.0 ng/mg for both CSP and MPB with good correlation coefficients (r(2) = 0.995). The intra-day precision and accuracy ranged from 1.5 to 9.3% and -17.5 to 3.6%, respectively, and the inter-day precision and accuracy ranged from 3.9 to 6.2% and -15.0 to -3.9%, respectively. The limits of detection for CSP and MPB were 0.13 and 0.12 ng/mg, respectively. The applicability of the method was proven by analyzing a hair sample from an authentic abuser.

NTP toxicity studies of carisoprodol (CAS No. 78-44-4) administered by Gavage to F344/N rats and B6C3F1 mice.

[carisoprodol structure: see text] Carisoprodol is a widely used skeletal muscle relaxant and analgesic and is available as a prescription drug. Comparative studies were conducted to determine the toxicity of carisoprodol administered in corn oil and in 0.5% methylcellulose by gavage. Carisoprodol plasma concentrations of rats and mice were measured at the end of the 13-week studies; single-dose plasma carisoprodol analyses were also performed. Genetic toxicity studies were conducted in Salmonella typhimurium, L5178Y mouse lymphoma cells, cultured Chinese hamster ovary cells, and peripheral blood erythrocytes of mice. Groups of 10 male and 10 female F344/N rats received 0, 100, 200, 400, 800, or 1,600 mg carisoprodol per kilogram body weight in corn oil by gavage or 0, 100, 200, 400, or 800 mg/kg carisoprodol in 0.5% methylcellulose by gavage for 13 weeks. Groups of 10 male and 10 female B6C3F1 mice received 0, 75, 150, 300, 600, or 1,200 mg/kg carisoprodol in corn oil by gavage or 0, 600, 1,200, or 1,600 mg/kg carisoprodol in 0.5% methylcellulose by gavage for 13 weeks. Among rats that received carisoprodol in corn oil, survival was similar to that of the vehicle controls. Survival of rats administered carisoprodol in 0.5% methylcellulose was also similar to that of the vehicle controls after adjustment for deaths (two males and one female in the 800 mg/kg group and two females in the 400 mg/kg group). The final mean body weight gain of males administered 1,600 mg/kg carisoprodol in corn oil was significantly less than that of the vehicle controls; the final mean body weights and body weight gains of female rats in the 800 and 1,600 mg/kg groups were significantly greater. In the carisoprodol in 0.5% methylcellulose study, males in the 200 mg/kg group and females in the 100 and 800 mg/kg groups had significantly greater mean body weights and body weight gains than did the vehicle controls. Clinical findings in rats administered carisoprodol in corn oil or in 0.5% methylcellulose included lethargy, ataxia, diarrhea, and prostration; the incidences were dose-related, and females were more sensitive than males to the effects of carisoprodol. In the carisoprodol in corn oil study, differences in hematology and clinical chemistry parameters occurred with no consistent patterns. The effects of carisoprodol in 0.5% methylcellulose on hematology and clinical chemistry parameters were not studied. In the corn oil study, the kidney and liver weights of male and female rats administered 200 mg/kg carisoprodol or greater were generally significantly greater than those of the vehicle controls. In the 0.5% methylcellulose study, liver weights were significantly greater in male rats administered 400 or 800 mg/kg and in female rats administered 800 mg/kg carisoprodol compared to the vehicle controls; however, a consistent effect on the kidney weights was not observed. Nephropathy was observed in male rats administered 400 mg/kg carisoprodol or greater in corn oil; the livers of four males in the 1,600 mg/kg group had centrilobular hypertrophy of hepatocytes. No lesions were observed histopathologically in female rats administered carisoprodol in corn oil. In the carisoprodol in 0.5% methylcellulose study, the severity of nephropathy in males administered 200 mg/kg or greater was enhanced, and the incidence of nephropathy in female rats in the 800 mg/kg group was slightly greater than that in the vehicle controls. Plasma carisoprodol concentrations at the end of 13 weeks generally increased with increasing dose in rats administered carisoprodol in corn oil or in 0.5% methylcellulose. The plasma carisoprodol concentrations in rats administered a single gavage dose of carisoprodol in corn oil also increased with increasing dose. In the carisoprodol in corn oil mouse study, two females each in the vehicle control and 75 mg/kg groups and one female each in the 150 and 600 mg/kg groups were accidentally killed; all males survived to the end of the study. One male and one female administered 1,600 mg/kg carisoprodol in 0.5% methylcellulose died; seven mice were accidentally killed. The mean body weights and body weight gains of mice administered carisoprodol in corn oil were generally similar to those of the vehicle controls. The final mean body weights and body weight gains of all groups of males and females administered carisoprodol in 0.5% methylcellulose were significantly less. Clinical findings in the carisoprodol in corn oil study included lethargy, ataxia, tremors, and prostration in male and female mice. Ataxia, lethargy, convulsions, and prostration were observed in all dosed groups of males and females administered carisoprodol in 0.5% methylcellulose. In the carisoprodol in corn oil study, liver weights were significantly greater in males administered 300 mg/kg or greater and in females administered 150 mg/kg or greater than in the vehicle controls. In the carisoprodol in corn oil study, no gross or microscopic lesions were considered related to carisoprodol administration. Minimal to mild centrilobular hypertrophy was observed in the liver of all dosed groups of males and in females in the 1,200 and 1,600 mg/kg groups in the carisoprodol in 0.5% methylcellulose study. The testis weights of males administered 1,200 mg/kg carisoprodol in corn oil were significantly less than those of the vehicle controls; the sperm motility of males in this group was also significantly less than that of the vehicle controls. There were no significant differences in vaginal cytology parameters between dosed and vehicle control females. At the end of the carisoprodol in corn oil study, the concentration of carisoprodol was above the limit of detection in the plasma of only one male mouse each in the 300 and 1,200 mg/kg groups and in four females in the 1,200 mg/kg group. In mice administered a single gavage dose of carisoprodol in corn oil, plasma concentrations increased with increasing dose; peak plasma concentrations occurred at 20 to 120 minutes in males and 60 to 120 minutes in females. In the carisoprodol in 0.5% methylcellulose study, plasma carisoprodol concentrations of female, but not male, mice increased with increasing dose; peak plasma carisoprodol concentrations occurred at 30 minutes postdosing in all groups of males and females. Results of proportionality and bioavailability studies indicated that single gavage doses of 200 to 800 mg/kg carisoprodol in 0.5% methylcellulose in rats or 300 to 1,200 mg/kg in mice were dose proportional; absolute bioavailability values increased with increasing dose, ranging from 15% to 32% for rats and from 18% to 38% for mice. For rats, the bioavailability of carisoprodol in 0.5% methylcellulose was approximately fivefold that of carisoprodol in corn oil; the Cmax values of the dose in 0.5% methylcellulose were approximately threefold those of the dose in corn oil. For mice, no significant difference was observed in the bioavailability of carisoprodol between the vehicles; however, the Cmax values of the dose in 0.5% methylcellulose were 1.5 to 1.75 times those of the dose in corn oil. Carisoprodol was not mutagenic in any of four strains of Salmonella typhimurium, with or without S9 metabolic activation. It did induce mutations in L5178Y mouse lymphoma cells in the absence of S9; with S9, no mutagenic activity was noted in this assay. Results of the sister chromatid exchange test with carisoprodol in cultured Chinese hamster ovary cells were considered equivocal with and without S9. Chromosomal aberrations in cultured Chinese hamster ovary cells were clearly increased by carisoprodol treatment, particularly in the presence of S9. No significant increases in the frequency of micronucleated erythrocytes were observed in peripheral blood samples from male and female mice administered carisoprodol by gavage for 13 weeks. In conclusion, carisoprodol induced ataxia and prostration in rats and mice, increases in liver weights in rats and mice, and nephropathy in male rats. The bioavailability of carisoprodol in 5% methylcellulose was greater than in corn oil. The no-observed-adverse-effect (NOAEL) level of carisoprodol administered in corn oil or in 0.5% methylcellulose was determined to be 100 mg/kg, compared to the clinical dose of 20 mg/kg per day for adults and 5 to 7.5 mg/kg per day for children.