New HPLC assay for urinary salbutamol concentrations in samples collected post-inhalation

Measurement Uncertainty and Validation for Quantitation of Salbutamol in Human Urine by Gas Chromatography-Tandem Mass Spectrometry

A simple, rapid, sensitive and specific gas chromatography-tandem mass spectrometry (GC-MS/MS) method was developed for quantitation of salbutamol in human urine using salbutamol-d3 as the internal standard. The processing of urines samples includes deconjugation with enzymatic hydrolysis, solid phase extraction procedure utilizing XAD2 column and liquid-liquid extraction accompanied by the derivatization by means of MSTFA/IODO-TMS/DTE mixture. The GC column was a HP Ultra-1 (17 m × 0.22 mm × 0.11 μm) used to separate the peak of interest. The data for GC-MS/MS were acquired and processed utilizing GC Labs Solution and Insight GCMS Software. The detection of spectra was performed on TQ 8050. This method included a chromatographic run of 13.67 min and the linearity was found over the concentration range of 250-2000 ng/mL with a regression coefficient (r2) of 0.99. The coefficient of variation for intra and interday assay precision was between 1.85 and 2.85% and the accuracy was between 95.50 and 107.04% for low quality control (QC), medium QC and high QC. The recovery was adequate to reliable detect the analyte at or below the level recommended by the World Anti-Doping Agency i.e., threshold 1000 ng/mL. The limit of detection and limit of quantification were found to be 10 and 100 ng/mL, respectively. The expanded measurement uncertainty (Uexp%) was found to be 8.28%.

Development of Nafion/single-walled carbon nanotube integrated arrays for the rapid detection of salbutamol doping

Salbutamol (SAL), a drug originally intended for the treatment of bronchial and pulmonary diseases, has repeatedly been used for doping in competitive sports. Herein, an integrated array (NFCNT array) that prepared by template-assisted scalable filtration using Nafion-coated single-walled carbon nanotube (SWCNT) is presented for the rapid field detection of SAL. Spectroscopic and microscopic measurements were used to confirm the introduction of Nafion onto the surface of the array and to analyze the resulting morphological changes. The effects of Nafion addition on the resistance and electrochemical properties of the arrays (e.g., the electrochemically active area, charge-transfer resistance, and adsorption charge) are also discussed in depth. With an electrolyte/Nafion/SWCNT interface and moderate resistance, the NFCNT-4 array prepared containing 0.04 wt% Nafion suspension exhibits the greatest voltammetric response to SAL. Subsequently, a possible mechanism for the oxidation of SAL was proposed, and a calibration curve in the range of 0.1-15 μM was established. Finally, the NFCNT-4 arrays were applied to the detection of SAL in human urine samples with satisfactory recoveries.

Relative Lung and Systemic Bioavailability Along with Oropharyngeal Deposition of Salbutamol Post-Inhalation: A Pharmacokinetic Evaluation of Novel Inhaler Technique Training Gadgets

Background: Suboptimal use of pressurized metered dose inhaler (pMDI) remains a major barrier to inhaled therapy success. Verbal inhaler technique training (VT) fails to maintain patients' good pMDI use, thus training tools might help. Trainhaler^® (THR device) and Flo-Tone^® CR (FTCR device), two novel pMDI technique training tools, were evaluated and compared in terms of relative lung and systemic bioavailability and oropharyngeal deposition of salbutamol inhaled from Ventolin^® Evohaler^® (GlaxoSmithKline) either alone following THR or connected to FTCR. Methods: Sixteen healthy adults inhaled 2 × 100 μg salbutamol puffs (1 minute apart) from Ventolin using the THR device or FTCR device in a two-period, randomized crossover study. A 7-day washout separated THR and FTCR approaches. Immediately after each puff inhalation, each subject gargled with 20 mL water for oropharyngeal deposition determination. Urine samples were collected 0.5 hour (pre-inhalation) and 0.5, 1.0, and 2.0 hours post-inhalation. Urine was then pooled till 24-hour post-inhalation. The relative lung bioavailability (0- to 0.5-hour urinary salbutamol excretion-USAL0.5) and relative systemic bioavailability (0- to 24-hour urinary excretion of salbutamol and its metabolite-USALMET24) were determined. Results: The mean (standard deviation [SD]) USAL0.5 of the THR and FTCR groups was 5.70 (6.43) and 11.39 (9.67) μg, respectively. The mean (SD) oropharyngeal deposition was 11.11 (4.37) and 6.09 (1.89) μg, respectively. The THR and FTCR devices were statistically significantly different in USAL0.5 and oropharyngeal deposition (p < 0.001), whereas there was no statistically significant difference in USALMET24. Conclusion: The THR device and the FTCR device showed positive impact on inhaled pMDI delivery. Indeed, the FTCR device doubled the relative lung bioavailability and minimized the unwanted oropharyngeal deposition of inhaled salbutamol. In practice, these pMDI trainers would complement and maintain VT. Study Registration: The study was registered on the ISRCTN registry (Reference: ISRCTN88332465-06/12/2017 [Prospectively Registered]).

Surface plasmon resonance biosensor for the detection of phenylethanolamine A in swine urine

In the present study, an antibody against phenylethanolamine A (PEA) was produced, confirmed, and used in a surface plasmon resonance (SPR)-based measurement. Bovine serum albumin (BSA)-conjugated PEA was linked to nano-gold particles bound to l-cysteine modified on the surface of a Au-NP sensor chip. The concentrations of antigen and antibody were optimized, and the designed biosensor chip was investigated to examine the stability and accuracy of the proposed method. The recovery of PEA ranged from 80.4-93.4% in swine urine samples with spike levels of 5, 10 and 20 ng mL-1, and the relative standard deviations of PEA were less than 2%. PEA analogues, such as clenbuterol, ractopamine, and salbutamol, did not influence the PEA measurement. The developed method could be used to measure PEA in swine urine samples.

Comparative pharmacokinetics of salbutamol inhaled from a pressurized metered dose inhaler either alone or connected to a newly enhanced spacer design

BACKGROUND

Coordination between actuation of a pressurized metered dose inhaler (pMDI) and inhalation is a critical manoeuvre that many patients fail to perform correctly. pMDIs connected to spacers do not require hand-lung coordination. This study evaluated the relative lung and systemic bioavailability and oropharyngeal deposition of salbutamol post-inhalation from Ventolin® Evohaler® (GlaxoSmithKline) either alone following verbal inhaler technique counselling (VC) or connected to a newly improved Able Spacer® (AS).

METHODS

In a two-period, randomized crossover study, 16 healthy adults inhaled 2 × 100 µg salbutamol puffs (1 min gap) from Ventolin using VC or AS. Immediately after each puff inhalation, each subject gargled with 20 mL water for oropharyngeal deposition (OD) determination. Urine samples were collected 0.5 h (pre-) and 0.5, 1.0 and 2.0 h post-inhalation. Urine was then pooled 2-24 h post-inhalation. The relative lung bioavailability (0-0.5 h urinary salbutamol excretion - USAL0.5) and systemic bioavailability (0-24 h urinary excretion of salbutamol and its metabolite - USALMET24) were determined. A one week washout separated VC and AS use.

RESULTS

The mean (SD) USAL0.5 of VC and AS was 5.36 (4.48) and 12.80 (10.83) µg, respectively. The mean (SD) OD was 11.35 (3.37) and 0.48 (0.30) µg, respectively. VC and AS were significantly different in USAL0.5 and OD (p<0.001). USALMET24 was comparable (p>0.05).

CONCLUSIONS

Compared with VC, AS doubled the inhaled salbutamol lung dose and minimised its precipitation in the oral cavity. The results suggest this inhalation aid can add therapeutic and safety benefits particularly in patients with continued pMDI technique issues despite repeated VC.

Development and validation of an UHPLC-MS/MS method for β2-agonists quantification in human urine and application to clinical samples

A fast analytical method for the simultaneous detection of 24 β₂-agonists in human urine was developed and validated. The method covers the therapeutic drugs most commonly administered, but also potentially abused β₂-agonists. The procedure is based on enzymatic deconjugation with β-glucuronidase followed by SPE clean up using mixed-phase cartridges with both ion-exchange and lipophilic properties. Instrumental analysis conducted by UHPLC-MS/MS allowed high peak resolution and rapid chromatographic separation, with reduced time and costs. The method was fully validated according ISO 17025:2005 principles. The following parameters were determined for each analyte: specificity, selectivity, linearity, limit of detection, limit of quantification, precision, accuracy, matrix effect, recovery and carry-over. The method was tested on real samples obtained from patients subjected to clinical treatment under chronic or acute therapy with either formoterol, indacaterol, salbutamol, or salmeterol. The drugs were administered using pressurized metered dose inhalers. All β₂-agonists administered to the patients were detected in the real samples. The method proved adequate to accurately measure the concentration of these analytes in the real samples. The observed analytical data are discussed with reference to the administered dose and the duration of the therapy.

Development of an ultrasensitive immunochromatographic assay (ICA) strip for the rapid detection of phenylethanolamine A in urine and pork samples

In this study a one-step immunochromatographic assay based on competitive format was developed for the rapid detection of phenylethanolamine A (PEAA) residues in urine and pork samples. A monoclonal antibody against PEAA was produced from BALB/c mice immunized with the PEAA-BSA conjugate. The results of this qualitative test strip were to be interpreted visually. The visual detection limit (VDL) and threshold level of the optimized immunochromatographic assay for PEAA were 0.1 ng/mL and 0.5 ng/mL, respectively. Cross-reactions with other β-agonists were not significant inhibitions to the performance of the test strip assay. The results from the test strip were in a good agreement with those obtained using a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) assay. The immunochromatographic assay developed here was a useful on-site screening tool that is rapid to use, low in cost, and extremely convenient for the detection of PEAA in urine samples and pork samples.

Development of a Microemulsion High Performance Liquid Chromatography (MELC) Method for Determination of Salbutamol in Metered-Dose Inhalers (MDIS)

INTRODUCTION

A sensitive and rapid oil-in-water (O/W) microemulsion high performance liquid chromatography (MELC) method has been developed. The water-in-oil (w/o) microemulsion was used as a mobile phase in the determination of salbutamol in aqueous solutions. In addition, the influence of operating parameters on the separation performance was examined.

METHODS

The samples were injected into C18, (250mm×4.6mm) analytical columns maintained at 25(o)C with a flow rate 1 ml/min. The mobile phase was 95.5% v/v aqueous orthophosphate buffer 20 mM (adjusted to pH 3 with orthophosphoric acid), 0.5% ethyl acetate, 1.5% Brij35, and 2.5% 1-butanol, all w/w. The salbutamol and internal standard peaks were detected by fluorescence detection at the excitation and emission wavelengths of 267 and 313 nm respectively.

RESULTS

The method had an accuracy of > 97.78% and the calibration curve was linear (r2 = 0.99) over salbutamol concentrations ranging from 25 to 500 ng/mL. The intra-day and inter-day precisions (CV %) were <1.6 and <1.8, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were 9.61ng/ml and 29.13ng/ml, respectively.

CONCLUSION

The method reported is simple, precise and accurate, and has the capacity to be used for determination of salbutamol in the pharmaceutical preparation.

Colorimetric detection of ractopamine and salbutamol using gold nanoparticles functionalized with melamine as a probe

A highly selective and sensitive method is developed for colorimetric detection of ractopamine and salbutamol using gold nanoparticles (AuNPs) functionalized with melamine (MA), respectively. The presence of these β-agonists induces the aggregation of gold nanoparticles through hydrogen-bonding interaction that was accompanied by a distinct change in color and optical properties, which could be monitored by a UV-vis spectrophotometer or even naked eyes. This process caused a significant decrease in the absorbance ratio (A670 nm/A520 nm) of melamine-gold nanoparticles (MA-AuNPs), and the color changed from wine red to blue. The systems exhibited a wide liner range, from 1×10(-10)M to 5×10(-7)mol/L with a correlation coefficient of 0.995 for ractopamine, and 1×10(-10)M to 1×10(-5)mol/L with a correlation coefficient of 0.996 for salbutamol, with measuring the absorbance ratio (A670 nm/A520 nm). The detection limit of these β-agonists is as low as 1×10(-11)mol/L. Particularly, the developed method has been applied to the analysis of real swine feed samples and has achieved satisfactory results.

Relative bioavailability of terbutaline to the lung following inhalation, using urinary excretion

AIMS

The aim of the study was to determine the relative lung and systemic bioavailability of terbutaline.

METHODS

On separate days healthy volunteers received 500 µg terbutaline study doses either inhaled from a metered dose inhaler or swallowed as a solution with and without oral charcoal. Urine samples were provided at timed intervals post dosing.

RESULTS

Mean (SD) urinary terbutaline 0.5 h post inhalation, in 12 volunteers, with (IC) and without (I) oral charcoal and oral (O) dosing was 7.4 (2.2), 6.5 (2.1) and 0.2 (0.2) µg. I and IC were similar and both significantly greater than O (P<0.001). Urinary 24 h terbutaline post I was similar to IC + O. The method was linear and reproducible, similar to that of the urinary salbutamol method.

CONCLUSIONS

The urinary salbutamol pharmacokinetic method post inhalation applies to terbutaline. Terbutaline study doses can replace routine salbutamol during these studies when patients are studied.

Single-Walled-Carbon-Nanotube-Modified Pyrolytic Graphite Electrode Used as a Simple Sensor for the Determination of Salbutamol in Urine

A fast and sensitive voltammetric method has been proposed for the determination of salbutamol at single-walled-carbon-nanotube-modified edge-plane pyrolytic graphite electrode (SWNT/EPPGE) in human urine. The electrochemical response of salbutamol was determined by square wave voltammetry (SWV) in phosphate buffer solution (PBS) at physiological pH 7.2. The modified electrode showed improved voltammetric response towards the oxidation of salbutamol, and a well-defined anodic peak was observed at~600 mV with enhanced peak current in comparison to the bare electrode. Linear calibration plot using SWNT/EPPGE was obtained in the concentration range of 50 to 2500 ngml-1with sensitivity and detection limit of 2.15 nA/ngml-1and 4.31 ngml-1, respectively. The developed method has been successfully applied for the determination of salbutamol in commercial preparations and human body fluids. Fast analysis of salbutamol in human urine makes the proposed method of great interest for doping control purposes at the site of competitive games.