Simultaneous determination of loratadine and pseudoephedrine sulfate in human plasma by liquid chromatography–electrospray mass spectrometry for pharmacokinetic studies

Application of the Gastrointestinal Simulator (GIS) Coupled with In Silico Modeling to Measure the Impact of Coca-Cola® on the Luminal and Systemic Behavior of Loratadine (BCS Class 2b)

In the present work, we explored if Coca-Cola^® had a beneficial impact on the systemic outcome of the weakly basic drug loratadine (Wal-itin^®, immediate-release formulation, 10 mg, generic drug product). To map the contribution of underlying physiological variables that may positively impact the intestinal absorption of loratadine, a multi-compartmental and dynamic dissolution device was built, namely the Gastrointestinal Simulator (GIS). The luminal behavior of one immediate-release (IR) tablet of 10 mg of loratadine was tested under four different fasted state test conditions in the GIS: (i) with 250 mL of water and applying a predetermined gastric half-life (t_1/2,G) of 15 min; (ii) with 250 mL of water and applying a t_1/2,G of 30 min; (iii) with 250 mL of Coca-Cola^® and a t_1/2,G of 15 min; (iv) with 250 mL of Coca-Cola^® and a t_1/2,G of 30 min. After initiating the experiments, solution concentrations and solubility were measured in the withdrawn samples, and pH was monitored. To address the impact of the present CO₂ in Coca-Cola^® on the disintegration time of the tablet, additional disintegration experiments were performed in a single-vessel applying tap water and sparkling water as dissolution media. These experiments demonstrated the faster disintegration of the tablet in the presence of sparkling water, as the present CO₂ facilitates the release of the drug. The buffer capacity of Coca-Cola^® in the presence of FaSSGF was 4-fold higher than the buffer capacity of tap water in the presence of FaSSGF. After performing the in vitro experiments, the obtained results were used as input for a two-compartmental pharmacokinetic (PK) modeling approach to predict the systemic concentrations. These simulations pointed out that (i) the present CO₂ in Coca-Cola^® is responsible for the enhancement in drug release and dissolution and that (ii) a delay in gastric emptying rate will sustain the supersaturated concentrations of loratadine in the intestinal regions of the GI tract, resulting in an enhanced driving force for intestinal absorption. Therefore, co-administration of loratadine with Coca-Cola^® will highly likely result in an increased systemic exposure compared to co-administration of loratadine with tap water. The mechanistic insights that were obtained from this work will serve as a scientific basis to evaluate the impact of Coca-Cola^® on the systemic exposure of weakly basic drugs for patients on acid-reducing agents in future work.

Monitoring phospholipids for assessment of matrix effects in a liquid chromatography-tandem mass spectrometry method for hydrocodone and pseudoephedrine in human plasma

Matrix effects resulting in ion suppression or enhancement have been shown to be a source of variability and inaccuracy in bioanalytical mass spectrometry. Glycerophosphocholines may cause significant matrix ionization effects during quantitative LC/MS/MS analysis and are known to fragment to form characteristic ions (m/z 184) in electrospray mass spectrometry. This ion was used to monitor ion suppression effects in the determination of hydrocodone and pseudoephedrine in human plasma as a means to track and avoid these effects. The m/z 184 ion fragment was detected in both plasma extracts and solutions of phosphatidylcholine. Post-column infusion studies showed that the ion suppression for both drugs and internal standards correlated with the elution of phospholipids. HPLC conditions were adjusted to chromatographically resolve the peaks of interest from the phospholipids. Upon repeated injection, the elution time of the phospholipids decreased while elution of the analyte peaks remained unchanged. This resulted in co-elution and significantly affected peak shape and internal standard response for the analytes. It was decided to use the phospholipid fragment to monitor this matrix effect in validation samples. The resulting method demonstrated intra-day and inter-day precision within 4.5 and 5.6% for hydrocodone and pseudoephedrine, respectively, and accuracy within 8.9 and 8.7% for hydrocodone, and pseudoephedrine, respectively. There was no statistically significant difference in the internal standard response for the determination with and without monitoring the phospholipid fragment ion. We found that monitoring the phospholipid fragment was useful in method development to avoid the matrix effects, and in routine analysis to provide a practical way to ensure the avoidance of matrix effects in each individual sample.

Development and evaluation of an efficient HPLC/MS/MS method for the simultaneous determination of pseudoephedrine and cetirizine in human plasma: Application to Phase-I pharmacokinetic study

A sensitive, simple and highly selective liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed and evaluated to determine simultaneously the concentrations of pseudoephedrine and cetirizine in human plasma. The chief benefit of the present method is the minimal sample preparation, as the procedure is only one-step protein precipitation. Two drugs were separated on a C(8) column and analyzed by LC/MS/MS using positive electrospray ionisation (ESI). The method had a chromatographic run time of 12.0 min and a linear calibration curve over the concentration range of 1.0-800 ng/ml for pseudoephedrine and 1.0-400 ng/ml for cetirizine, respectively. The lower limit of quantification of the two drugs was 1.0 ng/ml, respectively. The intra- and inter-batch precisions were less than 9.7%. The method described herein has been first used to reveal the pharmacokinetic characters in healthy Chinese volunteers treated with oral administration of different dosages of cetirizine dihydrochloride and controlled-released pseudoephedrine hydrochloride compound tablet, and approached the influence of a standard meal on the extent and rate of absorption of the combination tablet.

Detection and validated quantification of nine herbal phenalkylamines and methcathinone in human blood plasma by LC-MS/MS with electrospray ionization

The herbal stimulants Ephedra species, Catha edulis (khat), and Lophophora williamsii (peyote) have been abused for a long time. In recent years, the herbal drug market has grown owing to publicity on the Internet. Some ingredients of these plants are also ingredients of cold remedies. The aim of the presented study is to develop a multianalyte procedure for detection and validated quantification of the phenalkylamines ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, methylephedrine, methylpseudoephedrine, cathinone, mescaline, synephrine (oxedrine), and methcathinone in plasma. After mixed-mode solid-phase extraction of 1 ml of plasma, the analytes were separated using a strong cation exchange separation column and gradient elution. They were detected using a Q-Trap LC-ESI-MS/MS system (MRM mode). Calibration curves were used for quantification using norephedrine-d3, ephedrine-d3, and mescaline-d9 as internal standards. The method was validated according to international guidelines. The assay was selective for the tested compounds. It was linear from 10 to 1000 ng/ml for all analytes. The recoveries were generally higher than 70%. Accuracy ranged from - 0.8 to 20.0%, repeatability from 2.5 to 12.3%, and intermediate precision from 4.6 to 20.0%. The lower limit of quantification was 10 ng/ml for all analytes. No instability was observed after repeated freezing and thawing or in processed samples. The applicability of the assay was tested by analysis of authentic plasma samples after ingestion of different cold medications containing ephedrine or pseudoephedrine, and after ingestion of an aqueous extract of Herba Ephedra. After ingestion of the cold medications, only the corresponding single alkaloids were detected in human plasma, whereas after ingestion of the herb extract, all six ephedrines contained in the plant were detected. The presented LC-MS/MS assay was found applicable for sensitive detection and accurate and precise quantification of all studied analytes in plasma.

Simultaneous determination of desloratadine and pseudoephedrine in human plasma using micro solid-phase extraction tips and aqueous normal-phase liquid chromatography/tandem mass spectrometry

Cation-exchange micro solid-phase extraction (SPE) tips and aqueous normal-phase (ANP) chromatography coupled with tandem mass spectrometry were explored for the rapid, selective and sensitive quantitation of desloratadine and pseudoephedrine in human plasma. A novel micro-SPE device was evaluated for analyte capacity, extraction efficiency and its ability to maximize recovery of an analyte of interest from bioanalytical matrices by successive replicates of linked extraction steps. Ion suppression using two different methods with micro-SPE tips was negligible when compared to protein precipitation. The use of ANP chromatography eliminated the need for sample reconstitution following extraction and was found to be highly selective. A reliable chromatography system was developed with a short duty cycle of 2 min/sample. The proposed bioanalytical method required 50 microL of plasma for the determination of desloratadine and pseudoephedrine at limits of quantitation of 0.1 and 1.25 ng/mL, respectively. The analytical method was validated in accordance with the FDA guidance on bioanalytical method validation; selectivity, linearity, reproducibility and accuracy were all acceptable.

Determination of loratadine and its active metabolite in human plasma by high-performance liquid chromatography with mass spectrometry detection

A new sensitive and selective liquid chromatography coupled with mass spectrometry (LC/MS/MS) method for quantification of loratadine (LOR) and its active metabolite descarboethoxyloratadine (DSL) in human plasma was validated. After addition of the internal standard, metoclopramide, the human plasma samples (0.3 ml) were precipitated using acetonitrile (0.75 ml) and the centrifuged supernatants were partially evaporated under nitrogen at 37 degrees C at approximately 0.3 ml volume. The LOR, DSL and internal standard were separated on a reversed phase column (Zorbax SB-C18, 100 mmx3.0 mm i.d., 3.5 microm) under isocratic conditions using a mobile phase of an 8:92(v/v) mixture of acetonitrile and 0.4% (v/v) formic acid in water. The flow rate was 1 ml/min and the column temperature 45 degrees C. The detection of LOR, DSL and internal standard was in MRM mode using an ion trap mass spectrometer with electrospray positive ionisation. The ion transitions were monitored as follows: 383-->337 for LOR, 311-->(259+294+282) for DSL and 300-->226.8 for internal standard. Calibration curves were generated over the range of 0.52-52.3 ng/ml for both LOR and DSL with values for coefficient of determination greater than 0.994 by using a weighted (1/y) quadratic regression. The lower limits of quantification were established at 0.52 ng/ml LOR and DSL, respectively, with an accuracy and precision less than 20%. Both analytes demonstrated good short-term, long-term, post-preparative and freeze-thaw stability. Besides its simplicity, the sample treatment allows obtaining a very good recovery of both analytes, around 100%. The validated LC/MS/MS method has been applied to a pharmacokinetic study of loratadine tablets on healthy volunteers.