Determination of Some ß-Blockers and ß2-Agonists in Plasma and Urine Using Liquid Chromatography-tandem Mass Spectrometry and Solid Phase Extraction.

A highly sensitive method for the determinations of acebutolol, clenbuterol, nadolol, oxprenolol, propranolol, terbutaline and timolol ß-blockers and ß2-agonists in plasma and urine was developed. The method was optimized using electrospray ionization liquid chromatography-tandem mass spectrometry (LC-ESI-MS-MS) and clean screen solid phase extraction cartridges. Matrix effect was reduced by removing co-extractives from the SPE cartridges using methanol prior to drugs' elution. Using blood and serum matrices for calibration and applying the internal standard method has also contributed to the reduction of matrix effect. Method's validation yielded linear dynamic ranges of 5.0-50.0 and 50.0-1000.0 ng/ml for drugs spiked in plasma and urine respectively. It also gave correlation coefficients of 0.94-0.99, detection limits ranged in 0.06-5.04 pg/ml and quantification limits ranged in 0.14-22.88 pg/ml for the target drugs. Developed method was successfully applied to the analysis of ß-blockers and ß2-agonists in plasma and urine samples. Plasma samples fortified with drugs at 7.5, 40.0 and 75.0 ng/ml gave percentage recoveries ranged in 78.66-118.10, 67.02-83.97 and 74.77-93.80, respectively. Urine samples fortified with drugs at 80.0, 400.0 and 800.0 ng/ml gave percentage recoveries ranged in 104.68-130.18, 110.23-125.16 and 109.46-116.89, respectively. Variance coefficients ranged in 0.05-0.35 and 0.04-0.12 were, respectively, obtained for the analyses of drugs in plasma and urine samples. Results suggest that developed method is well suited for the analysis of investigated drugs in biological fluids.

Elimination and phase II metabolism of ethanol in camels after intravenous administration.

Ethanol elimination was studied in camels (n=8) after a single bolus intravenous dose of 0.1g/kg bodyweight (BW). Blood samples were then collected at set intervals. Ethanol and ethyl glucuronide (EtG) in blood were analysed by validated static headspace gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry (LC-MS) methods, respectively. Blood-ethanol concentration-time profiles were plotted for each camel and these were evaluated. A simple linear regression model was fitted to the selected data points and the slope of the fitted line was used to estimate the elimination rate, the distribution factor and turnover rate, which were 5.15 mg/dL blood/h, 0.55 L/kg and 0.028 g/h/kg, respectively. Blood EtG concentration-time profiles were also plotted for each camel. The elimination half-life of EtG, estimated by linear regression (using the values obtained after ethanol was completely eliminated) was 2.18 h. The theoretical initial blood concentration of EtG (C(0)), obtained by extrapolation to time zero was 23.4 µg/dL. The results will be useful in monitoring alcohol doping in camels using either parent drug or metabolite.

A fatal case of oleandrin poisoning.

The study presents a case of fatal poisoning with oleander leaves in an adult diabetic male. After repeated vomiting, and gastrointestinal distress the patient was admitted at the hospital with cardiac symptoms 1h after the ingestion. Urine samples were assayed immunochemically and by GC-MS for drugs of abuse and for general toxicological screen. Blood was analyzed for alcohol and volatiles by static head space GC-MS. Blood and oleander leaves were analyzed by LC-MS/MS for oleandrin and related compounds, the main cardiac glycosides of Nerium oleander. Oleandrin was detected by LC-MS/MS in the blood sample at a concentration of approximately 10 ng/ml. Another cardiac glycoside with pseudo-molecular ion of m/z 577, a likely structural isomer of oleandrin, was also detected in the blood and oleander leaves. However, by using the response as a function of concentration for oleandrin, this cardiac glycoside was roughly estimated at a concentration of approximately 10 ng/ml in the deceased blood. This would give a total fatal blood concentration of cardiac glycosides of about approximately 20 ng/ml in the deceased blood.

Lack of gender effect on the pharmacokinetics and pharmacodynamics of dexamethasone in the camel after intravenous administration.

The pharmacokinetics and pharmacodynamics of dexamethasone were studied in six male and six female camels after a single intravenous dose (0.05 mgkg(-1) body weight) of dexamethasone. The pharmacokinetic parameters of the two-compartment pharmacokinetic model for female and male camels, respectively (mean+/-SEM) were as follows: terminal elimination half-lives were 8.02+/-1.15 and 7.33+/-0.80 h, total body clearances were 95.5+/-16.0 and 124.5+/-11.9 ml h(-1) per kg, volumes of distribution at steady state were 0.72+/-0.08 and 0.87+/-0.14 litre kg(-1), and the volumes of the central compartment were 0.12+/-0.02 and 0.17+/-0.02 litre kg(-1). There was no significant difference in any pharmacokinetic parameter between female and male camels. Pharmacodynamic effects were evaluated by measuring endogenous plasma cortisol, circulating lymphocytes and neutrophils numbers and were analysed using indirect pharmacokinetic/pharmacodynamic models. The estimated IC50 of dexamethasone for cortisol and lymphocytes for female and male camels were 3.74+/-0.99 and 2.28+/-1.09 and 2.63+/-0.71 and 2.41+/-0.79 ng ml(-1), respectively. The EC50 for neutrophils for female and male camels were 24.5+/-5.83 and 20.2+/-3.82 ng ml(-1), respectively. There was no significant difference in any pharmacodynamic parameter between female and male camels. Dexamethasone in urine could be detected for 4-5 days by enzyme-linked immunosorbent assay and for 3-4 days by liquid chromatography/mass spectrometry after an intravenous dose of 0.05 mg kg(-1) body weight.

Rapid and sensitive static headspace gas chromatography-mass spectrometry method for the analysis of ethanol and abused inhalants in blood.

A sensitive and specific method using static headspace gas chromatography coupled with mass spectrometry (GC/MS) has been developed for the quantitative determination of ethanol in biological fluids using n-propanol as internal standard. Gas chromatography was performed in isothermal mode with a GC run time of 2.6 min. The quantification was performed using scan mode abstracting a quantitative ion and a qualifier ion for ethanol and for the internal standard. The method was linear (r(2), 0.999, in the concentration range of 5-200 mg/dl), specific (no interference from methanol acetaldehyde, acetone or from endogenous materials), sensitive (limit of quantification and limit of detection of 0.2 and 0.02 mg/dl, respectively) and robust (less than 5% inter- and intra-assay coefficient of variation). A slightly modified method was also developed for the quantification of five commonly abused inhalants (dichloromethane, ethyl acetate, benzene, toluene and xylene) in blood. The method used a gradient GC program with a run time of 8 min. The quantification was performed using scan mode and integrating the area under the peak using trichloroethane as an internal standard. Without optimization, the method was linear (from 5 to 100 mg/l) and sensitive.