Simultaneous quantitation of paracetamol, caffeine, pseudoephedrine, chlorpheniramine and cloperastine in human plasma by liquid chromatography–tandem mass spectrometry

Simultaneous determination of tramadol and paracetamol in human plasma using LC-MS/MS and application in bioequivalence study of -fixed-dose combination

The study aimed to develop a sensitive and high-throughput liquid chromatography coupled with tandem mass spectrometry method to quantify concentrations of tramadol and paracetamol simultaneously in human plasma. Sample preparation involved single-step protein precipitation using methanol and two deuterated internal standards, tramadol D6 and paracetamol D4. Agilent Poroshell 120 EC-C18 (100 × 2.1 mm, 2.1 µm) analytical column was employed to achieve chromatographic separation. Detection was in positive ion multiple reaction monitoring mode. A tailing factor (Tf) of <1.2, separation factor (K prime) of >1.5 from the column dead time and signal-to-noise (S/N) ratio >10, were obtained for analytes and internal standards. The standard curve was linear over the concentration range of 2.5-500.00 ng/mL for tramadol and 0.025-20.00 μg/mL for paracetamol. A small injection volume of 1 µL, low flow rate of 440 µL/min and short analysis time of 3.5 min reduced the solvent consumption, analysis cost and system contamination. The results of method validation parameters fulfilled the acceptance criteria of bioanalytical guidelines. The method was successfully applied to a bioequivalence study of fixed-dose combination products of tramadol and paracetamol in Malaysian healthy subjects.

Enhanced Acetaminophen Electrochemical Sensing Based on Nitrogen-Doped Graphene

Because of the widespread acetaminophen usage and the danger of harmful overdosing effects, developing appropriate procedures for its quantitative and qualitative assay has always been an intriguing and fascinating problem. A quick, inexpensive, and environmentally friendly approach based on direct voltage anodic graphite rod exfoliation in the presence of inorganic salt aqueous solution ((NH4)2SO4-0.3 M) has been established for the preparation of nitrogen-doped graphene (exf-NGr). The XRD analysis shows that the working material appears as a mixture of few (76.43%) and multi-layers (23.57%) of N-doped graphenes. From XPS, the C/O ratio was calculated to be 0.39, indicating a significant number of structural defects and the existence of multiple oxygen-containing groups at the surface of graphene sheets caused by heteroatom doping. Furthermore, the electrochemical performances of glassy carbon electrodes (GCEs) modified with exf-NGr for acetaminophen (AMP) detection and quantification have been assessed. The exf-NGr/GCE-modified electrode shows excellent reproducibility, stability, and anti-interfering characteristics with improved electrocatalytic activity over a wide detection range (0.1-100 µM), with a low limit for AMP detection (LOD = 3.03 nM). In addition, the developed sensor has been successfully applied in real sample analysis for the AMP quantification from different commercially available pharmaceutical formulations.

Stability-Indicating New RP-UPLC Method for Simultaneous Determination of a Quaternary Mixture of Paracetamol, Pseudoephedrine, Chlorpheniramine, and Sodium Benzoate in (Cold-Flu) Syrup Dosage Form

BACKGROUND

A combination of paracetamol, pseudoephedrine, chlorpheniramine, and sodium benzoate in (Cold-Flu) 1,2,3 Syrup dosage form is specified for the treatment of common cold and flu symptoms.

OBJECTIVE

The functional role of this study is to develop a novel, reliable, and selective stability-indicating reversed-phase ultra-performance liquid chromatography (RP-UPLC) method for simultaneous identification of a quaternary mixture of paracetamol, pseudoephedrine, chlorpheniramine, and sodium benzoate in (Cold-Flu) 1,2,3 Syrup dosage form.

METHOD

The specific method is accomplished using an Acquity UPLC HSS T3 C18 column (2.1 mm × 100 mm), 1.8 µm particle size with pore size 100 Å, utilizing a mixture of purified water-methanol-trifluoroacetic acid (72.5:27.5:1.5, v/v) as the mobile phase at a flow rate of 0.3 mL/min. The column void volume is 1.15 min. UPLC detection is adjusted at 205 nm using a photodiode array detector.

RESULTS

Calibration curves are obtained in the linearity ranges: 25-500 µg/mL for paracetamol, 10-50 µg/mL for pseudoephedrine, 0.5-5 µg/mL for chlorpheniramine, and 3-30 µg/mL for sodium benzoate with a correlation coefficient > 0.9992. The mean recovery of the developed method is tested and shows good recovery results between 99-101%; selectivity and forced degradation studies are investigated as per the International Council for Harmonisation Guidelines and no interference is detected due to degradation peaks.

CONCLUSION

The proposed stability-indicating UPLC method for simultaneous determination of the three drugs, paracetamol, pseudoephedrine, and chlorpheniramine, with a preservative sodium benzoate in (Cold-Flu) 1,2,3 Syrup dosage form is successfully accomplished, developed, and validated, and can be easily used in the analysis of drugs in pure or dosage form.

HIGHLIGHTS

The novelty of the current research work lies in the development of the UPLC method for simultaneous determination of a quaternary mixture of paracetamol, pseudoephedrine, chlorpheniramine, and sodium benzoate in (Cold-Flu) 1,2,3 Syrup dosage form.

In search of an ideal drug for safer treatment of obesity: The false promise of pseudoephedrine

Obesity is a major public health problem worldwide. Only relatively few treatment options are, at present, available for the management of obese patients. Furthermore, treatment of obesity is affected by the widespread misuse of drugs and food supplements. Ephedra sinica is an old medicinal herb, commonly used in the treatment of respiratory tract diseases. Ephedra species contain several alkaloids, including pseudoephedrine, notably endowed with indirect sympathomimetic pharmacodynamic properties. The anorexigenic effect of pseudoephedrine is attributable primarily to the inhibition of neurons located in the hypothalamic paraventricular nucleus (PVN), mediating satiety stimuli. Pseudoephedrine influences lipolysis and thermogenesis through interaction with β3 adrenergic receptors and reduces fat accumulation through down-regulation of transcription factors related to lipogenesis. However, its use is associated with adverse events that involve to a large extent the cardiovascular and the central nervous system. Adverse events of pseudoephedrine also affect the eye, the intestine, and the skin, and, of relevance, sudden cardiovascular death related to dietary supplements containing Ephedra alkaloids has also been reported. In light of the limited availability of clinical data on pseudoephedrine in obesity, along with its significantly unbalanced risk/benefit profile, as well as of the psychophysical susceptibility of obese patients, it appears reasonable to preclude the prescription of pseudoephedrine in obese patients of any order and degree.

Simultaneous determination of dantrolene and paracetamol in human plasma by liquid chromatography tandem mass spectrometry

A simple, sensitive, rapid and specific method based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the simultaneous quantification of dantrolene (DAN) and paracetamol (PAR) in real human plasma was developed and validated. The preparation of sample was achieved by liquid-liquid extraction with tertiary butyl methyl ether. The analysis was performed on a reversed-phase C₁₈column (1.7 µm, 2.1 × 30 mm) using acetonitrile: 0.1% formic acid (80:20, v/v) as the mobile phase and pumped in an isocratic mode at a flow rate of 0.3 mL/min using citalopram (CIT) as an internal standard. Tandem mass spectrometric detection was carried out by both positive and negative electrospray ionization (ESI) in the multiple-reaction monitoring mode (MRM). The analysis was carried out within 1 min for each sample which made it possible to analyze more than 350 human samples per day. Validation of the method was performed according to FDA guidelines for bio-analytical method. The method was found to be linear in the range of 25-2500 ng/mL and 100-10,000 ng/mL for DAN and PAR, respectively. The method was applied successfully for the determination of the two analytes in the plasma after oral administration of Dantrelax® compound capsules to healthy volunteers. The study was accomplished after approval of the ethics committee.

Magnetic solid-phase extraction of caffeine from surface water samples with a micro–meso porous activated carbon/Fe3O4 nanocomposite prior to its determination by GC-MS

A novel micro–meso porous activated carbon/Fe₃O₄ (Bm) composite was synthesized from the active charcoal precursor BAX-1500 and used in the magnetic solid-phase extraction (MSPE) of caffeine prior to its determination by gas chromatography-mass spectrometry (GC-MS). The main factors affecting the extraction and desorption steps of the MSPE procedure were investigated and optimized. These factors include extraction time, sorbent mass and salt addition for the adsorption step and type of eluent, desorption time and volume of desorption solution for the desorption step. Under optimum conditions, the absolute extraction recovery was found to be 91.1% and good linearity was observed in the investigated concentration range of 0.6–12.5 ng mL⁻¹ (R² = 0.9997). The limit of detection was 0.18 ng mL⁻¹ and the limit of quantification was 0.60 ng mL⁻¹. The method was successfully applied to the analysis of surface water samples. The proposed MSPE method is simple, rapid, sensitive and environmentally friendly.

A novel magnetic solid phase material based on a micro–meso porous activated carbon/Fe₃O₄ nanocomposite was used to extract caffeine from surface water samples. The method is efficient and rapid, and has minimum solvent consumption.

Identification and quantification of five impurities in cloperastine hydrochloride

Cloperastine hydrochloride, a piperidine derivative, is a drug substance with a central antitussive effect and widely used in cough treatment; and its impurities have not been reported. Herein we isolated and identified five impurities (named as impurity A, B, C, D and E) in cloperastine hydrochloride bulk drug and developed a quantitative HPLC method. First, impurity A, B, C were enriched by ODS column chromatography and isolated by semi-preparative HPLC, at the same time, impurity D was purified by ODS column chromatography. Then, impurity E was enriched by strong acid degradation and purified by semi-preparative HPLC. At last, their structures were characterized by a variety of spectral data (MS, ¹H NMR, ¹³C NMR, HSQC, HMBC and ¹H-¹H COSY). Impurity A was confirmed as 1-[2-(diphenylmethoxy)ethyl]piperidine, which having one less chloro-substituent compared with cloperastine. Impurity B was confirmed as 1-[2-[(2-chlorophenyl)(phenyl)methoxy]ethyl]piperidine, which was the isomer of cloperastine with 2-chloro-substituent. Impurity C was confirmed as 1-[2-[(3-chlorophenyl)(phenyl)methoxy]ethyl]piperidine, which was the isomer of cloperastine with 3-chloro-substituent. Impurity D was confirmed as (4-chlorophenyl)(phenyl)methanone, which was the raw material for the synthesis of cloperastine. Impurity E was confirmed as (4-chlorophenyl)(phenyl)methanol, which was an intermediate in the synthesis of cloperastine, and it was also a hydrolysate of cloperastine. Finally, the developed method was validated in terms of specificity, linearity, sensitivity, precision and accuracy.

Enantioselective LC-MS/MS method for the determination of cloperastine enantiomers in rat plasma and its pharmacokinetic application

Cloperastine is a central antitussive used to reduce the frequency and intensity of coughing on a short-term basis. In this study, a reliable chiral LC-MS/MS technology has been developed for the quantification of cloperastine enantiomers in the rat plasma. Carbinoxamine was selected as the internal standard. The enantioseparation of cloperastine was performed on a Chiralpak IA column with a mobile phase composed of acetonitrile-water-ammonium hydroxide (80:20:0.1, v/v/v) at a flow rate of 0.6 mL/min. Cloperastine enantiomers were detected by mass spectrometry in multiple reaction monitoring mode with a positive electrospray ionization source. The method was validated over the linear concentration range of 0.05 to 10.0 ng/mL (5.0 × 10^-4 ng to 0.10 ng) for both enantiomers. The lower limit of quantification (LLOQ) for each analyte was determined as 0.05 ng/mL. The relative standard deviations (RSDs) of intraday and interday precision was less than 13.9%, and the relative error (RE) of accuracy ranged from -5.4% to 6.1%, which were within the acceptance criteria. Finally, an application to the stereoselective pharmacokinetics of cloperastine in rats was successfully realized in our assay. The developed method on a commercially available Chiralpak IA column under isocratic mobile phase is advantageous to analyze cloperastine enantiomers in plasma samples collected for enantioselective metabolism or drug interaction studies.

Analytical methods for the determination of paracetamol, pseudoephedrine and brompheniramine in Comtrex tablets

Comtrex^® tablets composed of paracetamol, pseudoephedrine and brompheniramine are widely used for relieving symptoms related to common cold. This study has overcome the challenging dosage form ratio (250:15:1) and proposed chromatographic methods for analyzing the ternary combination were utilized displaying different apparatus, solvents and sensitivity ranges. Three chromatographic methods namely thin layer chromatography (TLC), high performance liquid chromatography with ultra-violet detection (HPLC–UV) and ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) were developed and validated for the simultaneous determination of the three drugs. Concerning the TLC method, aluminum TLC plates pre-coated with silica gel 60F₂₅₄ were used and methanol:water:ammonia (9:1:0.1, v/v/v) was applied as a mobile phase; scanning of the plates was carried out at 254 nm. For the HPLC–UV method C₁₈ column was used with an isocratic elution mobile phase composed of water:acetonitrile (75:25, v/v; pH 3.2) and the detection was at 210 nm. For the UPLC-MS/MS method; separation was performed on a UPLC-BEH C₁₈ column with methanol: 0.1% ammonium formate (60:40, v/v) as the mobile phase utilizing diphenhydramine as an internal standard and mass spectrometry was used for detection. The methods were simple, sensitive, accurate and precise. Statistical analysis revealed no significant difference from the reported methods in regard to accuracy and precision.

Inhibition of CYP2E1 With Propylene Glycol Does Not Protect Against Hepatocellular Injury in Human Acetaminophen Daily-Dosing Model

Acetaminophen (APAP)-induced liver injury is initiated by metabolism of APAP by the cytochrome P-450 (CYP) system, primarily CYP2E1. We previously demonstrated CYP inhibition following administration of a liquid APAP formulation containing propylene glycol, a CYP2E1 inhibitor, and other excipients. This study was undertaken to determine if propylene glycol specifically inhibits production of CYP-derived metabolites and if propylene glycol reduces the rise in alanine aminotransferase (ALT) seen following prolonged APAP dosing. Human subjects were randomized to receive 4 g of APAP daily in one arm of the study or 4 g of APAP with 5 mL of 99% propylene glycol in the other arm, both for 14 days. After a washout period of at least 14 days, subjects were crossed over between arms. Outcomes were rise of ALT greater than 2 times baseline (responders) and proportion of randomly sampled CYP-derived metabolites relative to total metabolites produced. There was no difference in percentage of responders between treatment groups: 6 of 21 in the APAP group (29%) compared with 8 of 20 in the APAP + propylene glycol group (40%); chi-square, P = .59. For all subjects, the mean percentage of CYP-derived metabolites produced was 5.8% (APAP) versus 4.3% (APAP + propylene glycol); P = .018. This effect was solely attributable to the responders: the mean percentage of CYP metabolites of responders was 7.7% (APAP) versus 4.6% (APAP + propylene glycol), P = .050, whereas there was no difference for the nonresponders. Five subjects were responders in both arms (2% probability of random occurrence). Our data indicates that propylene glycol inhibits CYP2E1 metabolism of APAP in some subjects but does not effect hepatocellular indury at the dose given.

HPLC Method for Quantification of Caffeine and Its Three Major Metabolites in Human Plasma Using Fetal Bovine Serum Matrix to Evaluate Prenatal Drug Exposure

Caffeine is recognized as the first-line therapeutic agent for apnea of prematurity. The dosage regimen is 10 mg/kg loading dose and 2.5 mg/kg maintenance dose. However, the plasma concentration achieved, not always, is therapeutically useful. It makes necessary to increase the doses to reach plasma concentration up to 30 or 35 μg/mL or even higher to attain therapeutic effect. To study why neonates have these differences, and whether these effects are linked to prenatal caffeine exposure, we had to develop an analytical method for an accurate measurement of caffeine and metabolites concentration. The analysis was carried out using fetal bovine serum (FBS) as biological matrix in a high-performance liquid chromatography with an ultraviolet detector method. This method allows acceptable chromatographic resolution between analytes in 15 minutes. It was validated and proved to be linear in the 0.1-40 µg/mL range for caffeine, paraxanthine, theobromine, and theophylline in the same chromatographic analysis. Accuracy for quality control samples for intra- and interday assays was ranged from 96.5 to 105.2% and 97.1 to 106.2%. Precision had CV no more than 10% in all concentration levels for all analytes. No differences were observed between quantification in human and FBS. This method was applied to quantify plasma drug concentration in mothers and their newborns in a Mexican northeast population. In our study, we confirmed self-reported caffeine maternal intake in 85.2% (n=23); meanwhile, in their newborn's plasma, it was detected only in 78% (n=21). Caffeine plasma concentrations in mother and newborn had a linear relationship, and no differences were observed between groups (mothers versus children). These results suggest that our analytical method and substitution of biological matrix was linear, precise, and accurate for caffeine quantification and could be used for measuring prenatal exposure and let us to study, in the future, concentration differences observed during apnea clinical treatment.

Use of continuous wavelet transform approach for simultaneous quantitative determination of multicomponent mixture by UV-Vis spectrophotometry

In the present paper, a multicomponent analysis approach based on spectrophotometry method was developed for simultaneous determination of Guaifenesin (GU), Chlorpheniramine (CHL) and Pseudoephedrine (PSE) without any separation steps. The method under study is signal processing method based on Continuous Wavelet Transform (CWT) coupled with zero cross point technique. In this paper, CWT method was tested by synthetic ternary mixtures and was applied to the commercial cough syrup as a real sample and assessed by applying the standard addition technique. For demonstrate the accuracy of the results, other applications of signal processing, such as Derivative Transform (DT), Partial Least Squares (PLS) regression and Principal Components Regression (PCR) were used as comparative methods. Afterwards, the obtained results from analyzing the cough syrup by all methods were compared to the High-Performance Liquid Chromatography (HPLC) as a reference method. One-way analysis of variance test at 95% confidence level showed no significant differences between CWT and other applications.

Postprandial metabolic responses to ingestion of bovine glycomacropeptide compared to a whey protein isolate in prediabetic volunteers

PURPOSE

Whey protein was shown to reduce blood glucose responses in humans and various other positive effects have been attributed to this protein. In contrast, studies using glycomacropeptide (GMP) as part of the whey fraction of bovine milk are rare. We, therefore, studied the postprandial responses to GMP administration in humans with impaired glucose tolerance compared to the effects of pure whey protein in a random design.

METHODS

Fifteen prediabetic volunteers received on different occasions one of three test drinks containing 50 g of maltodextrin19 (MD19) alone or in combination with either 50 g GMP or 50 g whey protein isolate (WPI). Blood was collected over 4 h with analysis of blood glucose and hormones, gastric emptying rate as well as plasma amino- and fatty acids, β-hydroxybutyrate and acylcarnitines.

RESULTS

The WPI drink reduced the AUC of venous blood glucose compared to the MD19 drink in the prediabetic group by 11% (p = 0.0018) whereas GMP reduced the AUC by 18% (p < 0.0001), significantly different to the WPI drink (p = 0.0384). The reduction in blood glucose after the GMP drink was accompanied by a significantly lower AUC of insulin (- 34%) than for the WPI drink. Levels of C-peptide and of glucose insulinotropic polypeptide (GIP) were highly increased after the WPI drink over the MD19 control drink but remained in essence unaffected by the GMP.

CONCLUSION

GMP reduced the glycemic response more potently than whey protein, whereas insulin output was less affected making GMP an interesting protein to control postprandial glucose responses.

Design of Optical Sensor Membrane Based on Polymer Poly(methyl methacrylate) for Paracetamol Detection in Traditional Herbal Medicine

Generally, regulation states that herbal medicines are remedies containing plants or preparation of plants as active ingredients only. Paracetamol is one of the drugs that is frequently added in herbal medicine to enhance the effect as an analgesic. The government regulation disallows chemical drugs contained in herbal medicine due to the toxic effect of uncontrolled consumption. On this study, the optical sensor membrane from polymer poly(methyl methacrylate) (PMMA) was synthesized by phase inversion method and was used to detect paracetamol in herbal medicine. PMMA was made in three different concentrations 5%, 7.5%, and 10% and was mixed with ferric chloride (FeCl3), Folin-Ciocalteu, and Nessler reagent as specific colorimetric reagents for paracetamol detection, with a ratio of solvent:reagent was 6:4; 7:3; and 8:2. The result of the experiment shows that PMMA-FeCl3 7.5% (7:3), PMMA-Folin 5% (6:4), and PMMA-Nessler 5% (6:4) give the best performance for paracetamol detection. Real herbal medicine samples were analyzed to confirm the practical application of this sensor, and the result shows good agreement with UV-Vis data. The results show that optical sensor membrane which has been developed can be used as new detection method of paracetamol for community application.

Simultaneous determination of amantadine and rimantadine in feed by liquid chromatography-Qtrap mass spectrometry with information-dependent acquisition

A sensitive method for simultaneous determination of amantadine and rimantadine in feed was developed using an ultra-high-performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry (UHPLC-Qtrap-MS) in the multiple reaction monitoring information-dependent acquisition-enhanced product ion (MRM-IDA-EPI) mode, and employing the mixed cation exchange (MCX) solid-phase extraction column as sample cleanup and amantadine-d₁₅ and rimantadine-d₄ as internal standards, respectively. Compared to traditional MRM mode, for the targeted drugs in feed simultaneously both the secondary mass spectra and MRM information can be obtained using UHPLC-Qtrap-MS with MRM-IDA-EPI mode, and thus more accurate qualitative confirmation results achieved even at lower concentration of 0.2 μg/L in acceptable purity fit values. After optimization of sample preparation, good linearities (R > 0.9994) were obtained over the concentration range from 1 to 200 μg/L for amantadine and rimantadine. The precision was validated by intra-day and inter-day, and the relative standard deviations were all within 9.61%. Mean recoveries ranged from 76.1 to 112% at spiked concentrations of 0.5-100 μg/kg in three types of feed samples, including formula feed and complex concentrated feed for pigs and premix feed for chicken. The limits of detection (LODs) and quantification (LOQs) were 0.2 and 0.5 μg/kg for both drugs, respectively. The application in real feed samples further proved the accuracy and reliability of the developed method. This method provides an important tool to detect illegal uses of amantadine and rimantadine in feed. Graphical abstract Simultaneous quantitation and qualitative confirmation of amantadine and rimantadine in feed by MRM-IDA-EPI.

Electrochemical detection of chlorpheniramine maleate in the presence of an anionic surfactant and its analytical applications

Improvement of methods for the detection of an analyte at a low concentration with high sensitivity has become an important point of interest. An effort has been made to know the electrochemical behavior of chlorpheniramine maleate in the presence of an anionic surfactant. Voltammograms were obtained in the range of 6.0–11.2 pH, and the maximum peak current (IP) was observed at pH 10.4. Various physicochemical parameters were estimated, including the process on the surface of the electrode, which was found to be diffusion controlled, heterogeneous rate constant, number of electrons transferred, and charge transfer coefficient. Square wave voltammetry of chlorpheniramine maleate at the modified electrode exhibited a linear calibration curve in the concentration range of 1.0–100 μmol/L, with a limit of detection of 28 nmol/L. The proposed technique was successfully used for the determination of chlorpheniramine maleate in pharmaceuticals, as well as in biological samples.

Resolution and quantification challenge of modern chemometric models in the determination of anti-migraine tablets containing ergotamine, caffeine, acetaminophen, and metoclopramide

Unique mixture of ergotamine (ERG), metoclopramide (MET), caffeine (CAF) and the study presents a comparison between five multivariate models in the determination of the paracetamol (PAR) in laboratory mixtures and in pharmaceutical formulations.

Carboxylic acid functionalized multi-walled carbon nanotube assisted centri-voltammetry as a new approach for caffeine detection

Centri-voltammetry provides centrifugation and voltammetry in a single cell and was applied to the caffeine detection for the first time.

Applications and challenges in using LC–MS/MS assays for quantitative doping analysis

LC–MS/MS is useful for qualitative and quantitative analysis of ‘doped’ biological samples from athletes. LC–MS/MS-based assays at low-mass resolution allow fast and sensitive screening and quantification of targeted analytes that are based on preselected diagnostic precursor–product ion pairs. Whereas LC coupled with high-resolution/high-accuracy MS can be used for identification and quantification, both have advantages and challenges for routine analysis. Here, we review the literature regarding various quantification methods for measuring prohibited substances in athletes as they pertain to World Anti-Doping Agency regulations.

Simultaneous quantification of acetaminophen and five acetaminophen metabolites in human plasma and urine by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry: Method validation and application to a neonatal pharmacokinetic study

Drug metabolism plays a key role in acetaminophen (paracetamol)-induced hepatotoxicity, and quantification of acetaminophen metabolites provides critical information about factors influencing susceptibility to acetaminophen-induced hepatotoxicity in clinical and experimental settings. The aims of this study were to develop, validate, and apply high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) methods for simultaneous quantification of acetaminophen, acetaminophen-glucuronide, acetaminophen-sulfate, acetaminophen-glutathione, acetaminophen-cysteine, and acetaminophen-N-acetylcysteine in small volumes of human plasma and urine. In the reported procedures, acetaminophen-d4 and acetaminophen-d3-sulfate were utilized as internal standards (IS). Analytes and IS were recovered from human plasma (10μL) by protein precipitation with acetonitrile. Human urine (10μL) was prepared by fortification with IS followed only by sample dilution. Calibration concentration ranges were tailored to literature values for each analyte in each biological matrix. Prepared samples from plasma and urine were analyzed under the same HPLC-ESI-MS/MS conditions, and chromatographic separation was achieved through use of an Agilent Poroshell 120 EC-C18 column with a 20-min run time per injected sample. The analytes could be accurately and precisely quantified over 2.0-3.5 orders of magnitude. Across both matrices, mean intra- and inter-assay accuracies ranged from 85% to 112%, and intra- and inter-assay imprecision did not exceed 15%. Validation experiments included tests for specificity, recovery and ionization efficiency, inter-individual variability in matrix effects, stock solution stability, and sample stability under a variety of storage and handling conditions (room temperature, freezer, freeze-thaw, and post-preparative). The utility and suitability of the reported procedures were illustrated by analysis of pharmacokinetic samples collected from neonates receiving intravenous acetaminophen.

Metabolic responses of healthy or prediabetic adults to bovine whey protein and sodium caseinate do not differ

BACKGROUND

Casein is considered a slowly digestible protein compared with whey protein, and this may cause differences in hormone responses and the kinetics of delivering amino acids into the circulation.

OBJECTIVE

We investigated whether postprandial plasma hormone and metabolite responses were different when bovine casein or whey protein was co-administered with carbohydrates in healthy and prediabetic adults.

METHODS

White healthy male adults (n = 15) and white, well-defined male and female prediabetic adults (n = 15) received test drinks randomly on 3 different occasions at least 2 d apart which contained 50 g of maltodextrin19 (MD19) alone or in combination with 50 g of whey protein isolate (WPI) or 50 g of sodium caseinate (SC). Blood samples were collected over a 240-min time period and were analyzed for hormone profiles and defined metabolites.

RESULTS

No evidence was found that gastric emptying was different between the 2 protein drinks. Both proteins increased peak plasma insulin concentrations in prediabetic persons by 96% compared with MD19 (each, P < 0.05), which was accompanied by a reduction of peak venous blood glucose by 21% (each, P < 0.0001) without a difference between the 2 proteins. Peak plasma glucagon concentrations increased by 101% in both groups after the protein drinks (P < 0.05). The WPI drink also increased peak plasma glucose-dependent insulinotropic polypeptide concentrations in healthy volunteers by 56% (P < 0.01). Differences in plasma metabolite concentrations in volunteers could be attributed exclusively to the differences in the amino acid composition of the 2 proteins ingested.

CONCLUSION

The WPI and the SC drinks similarly reduced postprandial glucose excursions when ingested with carbohydrates in healthy and prediabetic volunteers. Under our experimental conditions, however, no evidence was found that gastrointestinal processing of the 2 protein varieties differed substantially. This trial was registered at clinicaltrials.gov as DRKS00005682.

Pharmacokinetic of pseudoephedrine in rat serum with luminol-pepsin chemiluminescence system by flow injection analysis

Pepsin (Pep) accelerated the electron transferring rate of excited 3-aminophathlate and enhanced luminol-dissolved oxygen chemiluminescence (CL) intensity, and the flow injection (FI) luminol-Pep CL system was first developed. It was found that the CL intensity of luminol-Pep reaction could be remarkably inhibited by pseudoephedrine (PE); the decrement of CL intensity was linear to the logarithm of PE concentration in the range of 0.1∼100.0 nmol L(-1) with a detection limit of 0.03 nmol mL(-1) (3σ). At a flow rate of 2.0 mL min(-1), the complete process including washing and sampling was performed within 40 s, offering a sample throughput of 90 h(-1). This proposed method was successfully applied to determining PE in rat serum for 18 h after intragastric administration with the elimination ratio of 42.34 % and recoveries from 90.3 to 110.6 %. The pharmacokinetic results showed that PE could be rapidly absorbed into serum with peak concentration (C max) of 1.45 ± 0.18 g L(-1) at the time (T max) of 1.49 ± 0.02 h; the absorption half-life (0.35 ± 0.04 h), elimination half-life (1.86 ± 0.24 h), the area under curve (109.81 ± 6.03 mg L(-1) h(-1)), mean residence time (3.82 ± 0.27 h), and elimination rate constant (2.26 ± 0.23 L g(-1) h(-1)) in rats vivo were derived, respectively. The possible CL mechanism of luminol-Pep-PE reaction was discussed by FI-CL, fluorescence, and molecular docking (MD) methods.