Use of Polymer Inclusion Membranes (PIMs) as support for electromembrane extraction of non-steroidal anti-inflammatory drugs and highly polar acidic drugs.

The use of polymer inclusion membranes (PIMs) as support of 1-octanol liquid membrane in electromembrane extraction (EME) procedure is proposed. Synthesis of PIMs were optimized to a composition of 29% (w/w) of cellulose triacetate as base polymer and 71% (w/w) of Aliquat®336 as cationic carrier. Flat PIMs of 25µm thickness and 6mm diameter were used. EME protocol was implemented for the simultaneous extraction of four non-steroidal anti-inflammatory drugs (NSAIDs) (salicylic acid, ketoprofen, naproxen and ibuprofen) and four highly polar acidic drugs (anthranilic acid, nicotinic acid, amoxicillin and hippuric acid). Posterior HPLC separation of the extracted analytes was developed with diode array detection. Recoveries in the 81-34% range were obtained. EME procedure was applied to human urine samples.

Quantitative determination of five metabolites of aspirin by UHPLC-MS/MS coupled with enzymatic reaction and its application to evaluate the effects of aspirin dosage on the metabolic profile.

Acetylsalicylic acid (Aspirin, ASA) is a famous drug for cardiovascular diseases in recent years. Effects of ASA dosage on the metabolic profile have not been fully understood. The purpose of our study is to establish a rapid and reliable method to quantify ASA metabolites in biological matrices, especially for glucuronide metabolites whose standards are not commercially available. Then we applied this method to evaluate the effects of ASA dosage on the metabolic and excretion profile of ASA metabolites in rat urine. Salicylic acid (SA), gentisic acid (GA) and salicyluric acid (SUA) were determined directly by UHPLC-MS/MS, while salicyl phenolic glucuronide (SAPG) and salicyluric acid phenolic glucuronide (SUAPG) were quantified indirectly by measuring the released SA and SUA from SAPG and SUAPG after ß-glucuronidase digestion. SUA and SUAPG were the major metabolites of ASA in rat urine 24h after ASA administration, which accounted for 50% (SUA) and 26% (SUAPG). When ASA dosage was increased, the contributions dropped to 32% and 18%, respectively. The excretion of other three metabolites (GA, SA and SAPG) however showed remarkable increases by 16%, 6% and 4%, respectively. In addition, SUA and SUAPG were mainly excreted in the time period of 12-24h, while GA was excreted in the earlier time periods (0-4h and 4-8h). SA was mainly excreted in the time period of 0-4h and 12-24h. And the excretion of SAPG was equally distributed in the four time periods. We went further to show that the excretion of five metabolites in rat urine was delayed when ASA dosage was increased. In conclusion, we have developed a rapid and sensitive method to determine the five ASA metabolites (SA, GA, SUA, SAPG and SUAPG) in rat urine. We showed that ASA dosage could significantly influence the metabolic and excretion profile of ASA metabolites in rat urine.

New urea-modified paper substrate for enhanced analytical performance of negative ion mode paper spray mass spectrometry.

Electrospray ionization mass spectrometry (ESI-MS) analysis in the negative ion mode is adversely affected by ionization suppression caused by electrical discharge and the presence of salts. Paper spray mass spectrometry (PS-MS) also suffers from the above phenomenon, being built on principles similar to those of ESI. Herein, we report the use of a paper substrate modified by 1-[3-(trimethoxysilyl)propyl]urea to improve the sensitivity of quantitative PS-MS analysis in the negative ion mode. The obtained results demonstrated that the urea modified paper substrate can effectively bind anions and highly polar compounds in the sample solution, decreasing competitive ionization in the negative ion mode of PS-MS and significantly reducing the signal intensity of Cl- adducts. In addition, the analyte responses were also significantly improved owing to the decreased electrical discharge observed for the less polar surface to decrease electrical discharge. Compared to non-modified PS-MS, urea-modified PS-MS exhibits a much higher sensitivity, showing 2-109 times improved signal-to-noise ratio (S/N). In real sample analysis, the limits of detection (LODs) of salicylic acid in urine and terpene lactones in Ginkgo biloba extract (EGb) were improved 10-fold and 2-40-fold, respectively, compared to that of non-modified PS-MS.

Pharmacokinetics and in vitro efficacy of salicylic acid after oral administration of acetylsalicylic acid in horses.

BACKGROUND: Although acetylsalicylic acid (ASA) is not frequently used as a therapeutic agent in horses, its metabolite SA is of special interest in equestrianism since it is a natural component of many plants used as horse feed. This led to the establishment of thresholds by horse sport organizations for SA in urine and plasma. The aim of this study was to investigate plasma and urine concentrations of salicylic acid (SA) after oral administration of three different single dosages (12.5 mg/kg, 25 mg/kg and 50 mg/kg) of acetylsalicylic acid (ASA) to eight horses in a cross-over designed study. RESULTS: In the 12.5 mg/kg group, SA concentrations in urine peaked 2 h after oral administration (2675 µg/mL); plasma concentrations peaked at 1.5 h (17 µg/mL). In the 25 mg/kg group, maximum concentrations were detected after 2 h (urine, 2785 µg/mL) and 1.5 h (plasma, 23 µg/mL). In the 50 mg/kg group, maximum concentrations were observed after 5 h (urine, 3915 µg/mL) and 1.5 h (plasma, 45 µg/mL). The plasma half-life calculated for SA varied between 5.0 and 5.7 h. The urine concentration of SA fell below the threshold of 750 µg/mL (set by the International Equestrian Federation FEI and most of the horseracing authorities) between 7 and 26 h after administration of 12.5 and 25 mg/kg ASA and between 24 and 36 h after administration of 50 mg/kg ASA. For ASA, IC50 were 0.50 µg/mL (COX-1) and 5.14 µg/mL (COX-2). For salicylic acid, it was not possible to calculate an IC50 for either COX due to insufficient inhibition of both cyclooxygenases. CONCLUSION: The established SA thresholds of 750 µg//mL urine and 6.5 µg/mL plasma appear too generous and are leaving space for misuse of the anti-inflammatory and analgetic compound ASA in horses.

Second-order multivariate models for the processing of standard-addition synchronous fluorescence-pH data. Application to the analysis of salicylic acid and its major metabolite in human urine.

In the present work, we describe the determination of salicylic acid and its major metabolite, salicyluric acid, in spiked human urine samples, using synchronous fluorescence spectra measured in a flow-injection system with a double pH gradient. Because the fluorescent urine background constitutes a potentially interfering signal, it becomes necessary to achieve the second-order advantage. Moreover, due to significant changes in the signal of the analytes in the presence of the urine matrix, mainly for salicyluric acid, standard addition was required in order to obtain appropriate quantifications. Several second-order multivariate calibration models were evaluated for this purpose: PARAFAC and MCR-ALS in two different modes, and PLS/RBL.

Disposable terbium (III) salicylate complex imprinted membrane using solid phase surface fluorescence method for fast separation and detection of salicylic acid in pharmaceuticals and human urine.

In this work, a simple, low cost, selective and sensitive complex imprinted membrane (CIM) for solid-phase fluorescent detection was developed with terbium (III) salicylate as complex template. Terbium-sensitized luminescence was employed for monitoring salicylic acid (SA) based on the fluorescence enhancement effect of benzoic acid derivatives on lanthanide ion Tb (III). The resulting CIM showed good fluorescent response and high selectivity towards SA with Tb as pivot in protic solvents, while demonstrating better analytical performance than the controlled membranes. The optimized adsorption time was 10 min, indicating rapid kinetics of the imprinted membrane. The linear response of CIM to SA was from 0.20 to 10mg/L with limit of detection (LOD) of 0.040 mg/L. The prepared CIM was successfully applied to the analysis of salicylic acid in pharmaceuticals and spiked human urine with recoveries of 80.6%-88.1%. The analytical results of the proposed method were in good agreement with those obtained by high performance liquid chromatography (HPLC) method, indicating that the developed membrane has acceptable practicability for fast determination of SA in real samples.

Determination of salicylic acid in human serum and urine samples by high-performance liquid chromatography with post-column Ru(bipy)3(2+)-Ce(SO4)2 chemiluminescence detection.

A sensitive, novel and rapid chemiluminescence (CL) method combined with high-performance liquid chromatography (HPLC) separation for the determination of salicylic acid (SA) is described in this work. The method was based on the fact that SA could significantly enhance the CL of the reaction of cerium sulfate and the tris(2,2-bipyridyl) ruthenium(II) CL system in the presence of acid. Under the optimal conditions, the CL intensity was linear over concentrations of SA in the range of 0.02-10 × 10(-6) g/mL, with a detection limit of 8 × 10(-9) g/mL (S/N = 3). Also, the relative standard detection was 2.2% for 1.0 × 10(-7) g/mL (n = 11). The proposed method has been successfully applied to the analysis of SA in human serum samples and urine samples with satisfactory results.

A random urine test can identify patients at risk of mesalamine non-adherence: a prospective study.

OBJECTIVES: Mesalamine non-adherence is common among patients with ulcerative colitis (UC), and can be difficult to identify in practice. We sought to determine whether a random urine test for salicylates could be used as a marker of 5-aminosalicylic acid (5-ASA) ingestion and identify patients at risk of non-adherence. Our aim is to determine whether measurement of salicylates in a random urine sample correlates with 5-ASA levels, and predicts an individual's risk of mesalamine non-adherence. METHODS: Prospective observational study. Urinary salicylates (by colorimetry) and 5-ASA (by liquid chromatography and tandem-mass spectrometry) were measured in a random urine sample at baseline in patients and controls. Mesalamine adherence was quantified by patient self-reports at enrollment and pharmacy refills of mesalamine over 6 months. RESULTS: A total of 93 patients with UC taking mesalamine maintenance therapy were prospectively enrolled from the clinic. Random urine salicylate levels (by colorimetry) were highly correlated with urine 5-ASA metabolite levels (by mass spectrometry; R2=0.9). A random urine salicylate level above 15 mg/dl distinguished patients who had recently taken mesalamine from controls (area under the curve value 0.9, sensitivity 95%, specificity 77%). A significant proportion of patients (27%) who self-identified as "high adherers" by an adherence questionnaire (Morisky Medication Adherence Scale-8) had random levels of urine salicylate below this threshold. These patients were at higher risk of objectively measured non-adherence to mesalamine over the subsequent 6 months (RR: 2.7, 95% CI: 1.1-7.0). CONCLUSIONS: A random urine salicylate level measured in the clinic can identify patients who have not recently taken mesalamine, and who are at higher risk of longitudinal non-adherence. This test could be used to screen patients who may warrant interventions to improve adherence and prevent disease relapse.

A new approach to determine salicylic acid in human urine and blood plasma based on negative electrospray ion mobility spectrometry after selective separation using a molecular imprinted polymer.

This paper deals with a method based on negative electrospray ionization ion mobility spectrometry (ESI-IMS) as a detection technique. The method was used to determine the salicylic acid in human urine and plasma after selective separation of salicylic acid (SA) via molecular imprinted polymer (MIP). The ion mobility spectrum of salicylic acid in negative mode and the reduced mobility value for its ion peak is reported in this paper for the first time. In order to combine the technique with negative ESI-IMS, suitable experimental conditions related to MIP (e.g., Soxhlet extraction) were selected. The method was exhaustively validated in terms of sensitivity, imprinting factor, enrichment factor, and sorption capacity. The linear dynamic range of 0.02-2.00 µg mL(-1) and the relative standard deviation (RSD) below 6% were obtained for the analysis of SA through this method. The average recovery was calculated about 92% for the analyzed drug. Finally, human urine and plasma were analyzed and the feasibility of the proposed method was successfully verified by the efficient clean-up of the samples using MIP separation before the analysis by ESI-IMS.

Nanostructured conducting molecularly imprinted polymer for selective extraction of salicylate from urine and serum samples by electrochemically controlled solid-phase micro-extraction.

Overoxidized polypyrrole (OPPy) films templated with salicylate (SA) have been utilized as conducting molecular imprinted polymers (CMIPs) for potential-induced selective solid-phase micro-extraction processes. Various important fabrication factors for controlling the performance of the OPPy films have been investigated using fluorescence spectrometry. Several key parameters such as applied potential for uptake, release, pH of uptake and release solution were varied to achieve the optimum micro-extraction procedure. The film template with SA exhibited excellent selectivity over some interference. The calibration graphs were linear in the ranges of 5×10(-8) to 5×10(-4) and 1.2×10(-6) to 5×10(-4)mol mL(-1) and the detection limit was 4×10(-8) mol L(-1). The OPPy film as the solid-phase micro-extraction absorbent has been applied for the selective clean-up and quantification of trace amounts of SA from physiological samples. The results of scanning electron microscopy (SEM) have confirmed the nano-structure morphologies of the films.

Simultaneous determination of salicylic acid and salicylamide in biological fluids.

A new methodology for the simultaneous determination of salicylic acid and salicylamide in biological fluids is proposed. The strong overlapping of the fluorescence spectra of both analytes makes impossible the conventional fluorimetric determination. For that reason, the use of fluorescence decay curves to resolve mixtures of analytes is proposed; this is a novel technique that provides the benefits in selectivity and sensitivity of the fluorescence decay curves. In order to assess the goodness of the proposed method, a prediction set of synthetic samples were analyzed obtaining recuperation percentages between 98.2 and 104.6%. Finally, a study of the detection limits was done using a new criterion resulting in values for the detection limits of 8.2 and 11.6 µg L(-1) for salicylic acid and salicylamide respectively. The validity of the method was tested in human serum and human urine spiked with aliquots of the analytes. Recoveries obtained were 96.2 and 94.5% for salicylic acid and salicylamide respectively.

Direct injection horse urine analysis for the quantification and identification of threshold substances for doping control. III. Determination of salicylic acid by liquid chromatography/quadrupole time-of-flight mass spectrometry.

In equine sport, salicylic acid is prohibited with a threshold level of 750 microg mL(-1) in urine; hence, doping control laboratories have to establish quantitative and qualitative methods for its determination. A simple and rapid liquid chromatographic/mass spectrometric method was developed and validated for the quantification and identification of salicylic acid. Urine samples after 900-fold dilution and addition of the internal standard (4-methylsalicylic acid) were directly injected to the liquid chromatography/quadrupole time-of-flight mass spectrometry system. Electrospray ionization in negative mode with full scan acquisition mode and product ion scan mode were chosen for the quantification and identification of salicylic acid, respectively. Run time was 2.0 min. The tested linear range was 2.5-50 microg mL(-1) (after 100-fold sample dilution). The relative standard deviations of intra- and inter-assay analysis of salicylic acid in horse urine were lower than 2.5% and 2.8%, respectively. Overall accuracy (relative percentage error) was less than 3.3%. Method was applied to two real samples found to be positive for salicylic acid, demonstrating simplicity, accuracy, and selectivity.

Salicylic acid sans aspirin in animals and man: persistence in fasting and biosynthesis from benzoic acid.

Salicylic acid (SA), which is central to defense mechanisms in plants and the principal metabolite of aspirin, occurs naturally in man with higher levels of SA and its urinary metabolite salicyluric acid (SU) in vegetarians overlapping with levels in patients on low-dose aspirin regimens. SA is widely distributed in animal blood. Fasting for major colorectal surgery did not cause disappearance of SA from plasma, even in patients following total proctocolectomy. A (13)C(6) benzoic acid load ingested by six volunteers led, between 8 and 16 h, to a median 33.9% labeling of urinary salicyluric acid. The overall contribution of benzoic acid (and its salts) to the turnover of circulating SA thus requires further assessment. However, that SA appears to be, at least partially, an endogenous compound should lead to reassessment of its role in human (and animal) pathophysiology.

Multicommuted fluorometric multiparameter sensor for simultaneous determination of naproxen and salicylic acid in biological fluids.

A combined approach based on solid-phase optosensing and multicommutation principles has been applied to develop a method for the simultaneous analysis of two pharmaceuticals (naproxen and salicylic acid) in biological fluids. The multicommuted flow-through optosensor was based on direct native fluorescence measurements of both analgesics using a non-polar sorbent (C18 silica gel) as a solid sensing zone. The flow system was controlled by Java-written home-made software and designed using three-way solenoid valves for an independent automated manipulation of sample and carrier solutions. Using an optimized sampling time, the method was calibrated in the range of 1 - 25 and 5 - 200 ng mL(-1). The obtained detection limits were 0.3 and 1.3 ng mL(-1) for naproxen and salicylic acid, respectively, with RSD (%) values of better than 2% for both analytes. The proposed methodology was successfully applied to urine, serum and pharmaceutical preparations. Recovery percentages ranging from 96.1 to 104% were obtained for both analytes.

Salicylic acid determination in cow urine and drugs using a bienzymatic sensor.

An enzymatic biosensor was developed for salicylic acid (salicylate ion) determined using a Clark type gas diffusion electrode and two enzymes (tyrosinase and salicylate hydroxylase) entrapped in a cellulose triacetate membrane. After optimization, the method was applied to the determination of salicylic acid in cow urine. Relatively good recoveries were achieved, between about 83% and 109%, using the calibration curve, and acceptable precision (R.S.D. about 8%). The method is now being tested for the determination of salicylic acid contained in commercially available drug specialities or galenic products. So far agreement with nominal values has been found to be between 75% and 110% with a R.S.D. of less than 8%.

Increased salicylate concentrations in urine of human volunteers after consumption of cranberry juice.

The aim of this study was to assess whether regular consumption of cranberry juice results in elevations in urinary salicylate concentrations in persons not taking salicylate drugs. Two groups of healthy female subjects (11/group) matched for age, weight, and height consumed 250 mL of either cranberry juice or a placebo solution three times a day (i.e., 750 mL/day) for 2 weeks. At weekly intervals, salicylic acid and salicyluric acid (the major urinary metabolite of salicylic acid) concentrations were determined in urine by HPLC with electrochemical detection. Concentrations of salicylic acid in plasma were also determined. Consumption of cranberry juice was associated with a marked increase (p < 0.001) of salicyluric and salicylic acids in urine within 1 week of the intervention. After 2 weeks, there was also a small but significant (p < 0.05) increase in salicylic acid in plasma. The regular consumption of cranberry juice results in the increased absorption of salicylic acid, an anti-inflammatory compound that may benefit health.

[Development of salicylic acid detector tube].

A detector tube was successfully devised for the screening of salicylic acid in urine. It, named "salicylic acid detector tube", consists of glass tube in which silica gel coated with 5% (w/w) of ferric chloride is enclosed. A pipette rubber cap was attached to an end of the tube, and another end was inserted into urine sample. The sample was then introduced into the tube, the color of the reagent immediately turned purple under the condition of more than 50 microg/ml of salicylic acid in urine. This device was useful for the emergency screening of salicylic acid in acute poisoning cases with aspirin.

The analysis of methyl salicylate and salicylic acid from Chinese herbal medicine ingestion.

This paper presents a multi-drug fatality in which methyl salicylate was ingested. It is presented to inform the toxicological community that a particularly expeditious method of detection for methyl salicylate exists. Previously published methods for the analysis of methyl salicylate include a gas chromatographic-mass spectrometric method and an alkaline/acidic extraction followed by high-performance liquid chromatographic (HPLC) analysis. This article describes a method for analyzing methyl salicylate using HPLC, in which a simple, rapid extraction procedure is used. Using a previously published HPLC method, methyl salicylate and salicylic acid were easily identified in biological specimens. Methyl salicylate and salicylic acid were detected using an extraction solution of acetonitrile coupled with internal standard and then analyzed by HPLC-diode-array detection. Because of its concentrated liquid form, methyl salicylate ingestion can cause rapid onset salicylate toxicity. As the potentially fatal methyl salicylate forms are readily available and easily found on drugstore shelves, the need to rapidly detect and quantitate salicylic acid concentrations that are due to methyl salicylate ingestion may arise. In the case presented, the peripheral blood concentration of salicylic acid from methyl salicylate ingestion was 320 mg/L, and the concentration in gastric contents was 820 mg. It alone was not the cause of death, however. The discovery of the ability to detect and quantitate methyl salicylate was due to its suspected ingestion.

Comparative pharmacokinetics of acetyl salicylic acid and its metabolites in children suffering from autoimmune diseases.

UNLABELLED: The aim of the present study was to compare the effect produced by juvenile rheumatoid arthritis (JRA) or rheumatic fever (RF) on the pharmacokinetics of acetyl salicylic acid (ASA) and its metabolites in children with autoimmune diseases (AD). METHODS: A prospective, open labelled study was performed in 17 children with JRA and 17 with RF who received a single dose of 25 mg ASA/kg orally. The pharmacokinetics of ASA and its metabolites were determined. The blood and urine levels of each salicylate collected during 24 h were measured by HPLC. A group of 15 healthy teenage volunteers was included as a control group. RESULTS: The maximum plasma concentration, half-life time, area under the curve and the amount of salicylates excreted were statistically different between the JRA and the RF groups, as well as between the RF group and the controls, however, there were no significant differences between the JRA group and the controls. CONCLUSIONS: Dosage schemes must be adjusted for JRA patients, since the half life in these patients is longer than in RF patients. However, due to ample variability of pharmacokinetic parameters it is recommended that dose schemes are individualized on the type of autoimmune disease considered.

First- and second-order multivariate calibration applied to biological samples: determination of anti-inflammatories in serum and urine.

First- and second-order multivariate calibration of fluorescence data have been compared as regards the determination of anti-inflammatories and metabolites in the biological fluids serum and urine. The simultaneous resolution of naproxen-salicylic acid mixtures in serum and naproxen-salicylic acid-salicyluric acid mixtures in urine was accomplished and employed for a discussion of the relative advantages of the applied chemometric tools. The analysis of second-order fluorescence excitation-emission matrices was performed using iteratively reweighted generalized rank annihilation method (IRGRAM), parallel factor analysis (PARAFAC), and self-weighted alternating trilinear decomposition (SWATLD). The results were compared with first-order fluorescence emission data analyzed with partial least-squares regression (PLS). In all cases, the performance of the methods was improved through the formation of inclusion complexes of the analytes with beta-cyclodextrin. The concentration ranges in which the analytes could be determined were as follows: naproxen, 0-250 ng mL(-1) in serum and 0-200 ng mL(-1) in urine; salicylic acid, 0-500 ng mL(-1) in serum and 0-300 ng mL(-1) in urine, and salicyluric acid, 0-300 ng mL(-1) in urine.