A simple chromatographic method for determining norfloxacin and enoxacin in pharmacokinetic study assessing CYP1A2 inhibition

We developed a simple assay method for the determination of serum and urine norfloxacin and enoxacin using reversed‐phase high‐performance liquid chromatography and perchloric acid precipitation for sample pre‐treatment. Optimized conditions can permit detection of norfloxacin and enoxacin in the same chromatogram, so either compound can be used as an internal standard for another determinant. Supernatants of the precipitated samples were analyzed by the octadecylsilyl silica‐gel column under ambient temperature and an ultraviolet wavelength of 272 nm. A mobile phase solvent consisting of 20 mm sodium dihydrogenphosphate (pH 3.0) and acetonitrile (85:15, v/v) was pumped at a flow rate of 1.0 mL/min. The calibration curves for norfloxacin and enoxacin at a concentration of 62.5–1000 ng/mL for serum and 250–4000 ng/mL for urine were linear (r > 0.9997). The recoveries of norfloxacin and enoxacin from serum and urine were >94% with the coefficient of variations (CV) <5%. The CVs for intra‐ and inter‐day assay of norfloxacin and enoxacin were <4.2 and <5.5%, respectively. This method can be applied to the pharmacokinetic study of norfloxacin and enoxacin after repeated administration to assess changes in CYP1A2 activity in healthy subjects. Copyright © 2010 John Wiley & Sons, Ltd.     

Simultaneous Determination of Tranexamic Acid and Losartan Potassium in Dosage Formulations and Human Serum by RP-LC

Rapid liquid chromatographic procedure for analytical quality control of pharmaceutical preparations and human serum containing drugs, tranexamic acid together with losartan potassium are proposed, using acetonitrile: water (50:50), adjusting pH to 2.6 with phosphoric acid as a mobile phase, UV detection at 205 nm and propylparaben sodium was used as internal standard. The results obtained showed a good agreement with the declared contents. The method shows good linearity in the range of 40–10,000 ng mL^?1 for tranexamic acid serum concentrations with a correlation coefficient 0.9999 (inter- and intra-day CV <3.18) and in the range 5–10,000 ng mL^?1 for losartan potassium serum concentrations with a correlation coefficient 0.9999 (inter- and intra-day CV <3.61). The recovery was >97.8%. The proposed method may be used for the quantitative analysis of tranexamic acid and losartan potassium alone or in combination from raw materials, in bulk drugs, dosage formulations and in serum.     

High‐performance liquid chromatography–tandem mass spectrometry for simultaneous determination of raltegravir,dolutegravir and elvitegravir concentrations in human plasma and cerebrospinal fluid samples

A simple sample treatment procedure and sensitive liquid chromatography–tandem mass spectrometry method were developed for the simultaneous quantification of the concentrations of human immunodeficiency virus‐1 integrase strand transfer inhibitors – raltegravir, dolutegravir and elvitegravir – in human plasma and cerebrospinal fluid (CSF). Plasma and CSF samples (20 μL each) were deproteinized with acetonitrile. Raltegravir‐d₃ was used as the internal standard. Chromatographic separation was achieved on an XBridge C₁₈ column (50 × 2.1 mm i.d., particle size 3.5 μm) using acetonitrile–water (7:3, v/v) containing 0.1% formic acid as the mobile phase at a flow rate of 0.2 mL/min. The run time was 5 min. Calibration curves for all three drugs were linear in the range 5–1500 ng/mL for plasma and 1–200 ng/mL for CSF. The intra‐ and inter‐day precision and accuracy of all three drugs in plasma were coefficient of variation (CV) <12.9% and 100.0 ± 12.2%, respectively, while those in CSF were CV <12.3% and 100.0 ± 7.9%, respectively. Successful validation under the same LC–MS/MS conditions for both plasma and CSF indicates this analytical method is useful for monitoring the levels of these integrase strand transfer inhibitors in the management of treatment of HIV‐1 carriers.     

Development and validation of an ultra‐performance liquid chromatography method for simultaneous analysis of 20 antihistaminics in dietary supplements

The purpose of this study was to develop and validate an ultra‐performance liquid chromatography method for simultaneous analysis of 20 antihistamines (illegal additives) in dietary supplements. The limits of detection and quantitation of the method ranged from 1.5 to 2.5 µg/mL and from 20.0 to 50.0 µg/mL, respectively. The determination coefficient was >0.999, precisions were 0.2–5.1% (intra‐day) and 0.1–8.8% (inter‐day), and accuracies were 84.5–111.2% (intra‐day) and 91.9–112.0% (inter‐day). The mean recoveries of 20 targeted compounds from dietary supplements ranged from 75.4 to 119.3%. The relative standard deviations were <6.6% and complied with established international guidelines. The relative standard deviation of stability was <0.8%. Fifty‐two commercially available dietary supplements were evaluated using this method, and were found to have none of the 20 antihistamines in significant abundance. Copyright © 2014 John Wiley & Sons, Ltd.     

Determination of zearalenone by liquid chromatography/tandem mass spectrometry and application to a pharmacokinetic study

Zearalenone, a mycotoxin biosynthesized by various Fusarium fungi, is widely found as a contaminant in grains and animal feeds. This study describes a rapid and sensitive LC/MS/MS assay method for the quantification of zearalenone in rat serum. The assay was validated to demonstrate the specificity, linearity, recovery, lower limit of quantification (LLOQ), accuracy and precision. The multiple reaction monitoring was based on the transition of m/z 317.0 → 130.9 for zearalenone and 319.0 → 204.8 for zearalanone (internal standard). The assay utilized a single liquid–liquid extraction with t‐butyl methyl ether and isocratic elution, and the LLOQ was 0.5 ng/mL using 0.1 mL rat serum. The assay was linear over a concentration range from 0.5 to 200 ng/mL, with correlation coefficients >0.9996. The mean intra‐ and inter‐day assay accuracy was 101.2–112.9 and 96.3–108.0%, respectively. The mean intra‐ and inter‐day precision was between 1.3–7.6 and 3.6–10.6%, respectively. The developed assay was applied to a pharmacokinetic study after a bolus intravenous injection of zearalenone in rats. Copyright © 2009 John Wiley & Sons, Ltd.     

Simultaneous Determination of Ceftriaxone Sodium and Non Steroidal Anti‐Inflammatory Drugs in Pharmaceutical Formulations and Human Serum by RP‐HPLC

An accurate, sensitive and least time consuming reverse phase high performance liquid chromatographic (RP‐HPLC) method for the estimation of ceftriaxone in the presence of non steroidal anti‐inflammatory drugs in formulation and human serum has been developed and validated. Chromatographic separation was conducted on prepacked Purospher Star, C18 (5 μm, 250 × 4.6 mm) column at room temperature using methanol:water:acetonitrile (80:15:5 v/v/v) as a mobile phase, pH adjusted at 2.8 with ortho‐phosphoric acid and at a flow rate of 1.0 mL/minute, while UV detection was performed at 270 nm. The results obtained showed a good agreement with the declared content. The method shows good linearity in the range of 2.5‐25 μg/mL ceftriaxone serum concentrations with a correlation coefficient 0.999 (inter‐ and intra‐day RSD < 2.0%). The limit of detection and quantification for ceftriaxone and NSAID's in pharmaceutical formulation and serum were in the range 0.51‐1.54 μg/mL. Analytical recovery was >98.1%. The proposed method may be used for the quantitative analysis of commonly administered non steroidal anti‐inflammatory drugs i.e. tiaprofenic acid, naproxen sodium, flurbiprofen, diclofenac acid and mefenamic acid alone or in combination with ceftriaxone from raw materials, dosage formulations and in serum. The established HPLC method is rapid, accurate and selective, because of its sensitivity and reproducibility.     

Quantitative determination of regorafenib and its two major metabolites in human plasma with high‐performance liquid chromatography and ultraviolet detection

A simple, highly sensitive and specific high‐performance liquid chromatography (HPLC) method was developed for the simultaneous quantitation of regorafenib, N‐oxidemetabolite (M‐2) and the desmethyl N‐oxide metabolite (M‐5) in human plasma. Regorafenib, M‐2, M‐5 and the internal standard sorafenib were separated using a mobile phase of 0.5% KH₂PO₄ (pH 3.5)–acetonitrile (30:70, v/v), on a Capcell PAK MG II column at a flow rate of 0.5 mL/min and measurement at UV 260 nm. The lower limits of quantification for regorafenib, M‐2 and M‐5 were 10 ng/mL for each analyte. A procedure using solid‐phase extraction required only a small amount of plasma (100 μL) for one analysis while providing high extraction recovery (>81% for all compounds) and good selectivity. Coefficients of variation for intra‐ and inter‐day assays were <12.2% for regorafenib, <12.3% for M‐2 and <15.1% for M‐5. Accuracies for intra‐ and inter‐day assays were <9.4% for regorafenib, <8.0% for M‐2 and <12.8% for M‐5 over a linear range from 10 to 10,000 ng/mL. This HPLC assay is suitable for clinical pharmacokinetic studies of regorafenib. The present HPLC method is currently in use for our observational studies of patients under treatment. Copyright © 2016 John Wiley & Sons, Ltd.     

Development and validation of a UPLC–MS/MS method for determination of Sarsasapogenin‐AA22 in rat plasma and its application to a pharmacokinetic study

A sarsasapogenin derivative, sarsasapogenin‐AA22 (AA22), with cyclobutylamine at the 3‐hydroxyl position of sarsasapogenin, has great neuroprotective activity in PC12 cells and NO production inhibitory activity in RAW264.7 cell lines. A method was developed to determine AA22 in rat plasma which was further applied to evaluate the pharmacokinetics of AA22 after taking a single dose of AA22. Liquid chromatography tandem mass spectrometry was used in the method, while diosgenin was used as internal standard. A simple protein precipitation based on acetonitrile was utilized. A simple sample cleanup promoted the throughput of the method considerably. The method was validated over the range of 1–1000 ng/mL with a correlation coefficient > 0.99. The lower limit of quantification was 1 ng/mL for AA22 in plasma. Intra‐ and inter‐day accuracies for AA22 were 92–111 and 100–103%, respectively, and the inter‐day precision was <15%. After a single oral dose of 25 mg/kg of AA22, the mean peak plasma concentration of AA22 was 2114 ± 362 ng/mL at 6 h. The area under the plasma concentration–time curve was 196,098 ± 69,375 h ng/mL, and the elimination half‐life was 8.7 ± 2.2 h.     

Development and application of a UPLC‐MS/MS method for simultaneous determination of fenofibric acid and berberine in rat plasma: application to the drug–drug pharmacokinetic interaction study of fenofibrate combined with berberine after oral administration in rats

With the purpose of carrying out pharmacokinetic interaction studies ofnberberine (BBR) and fenofibrate (FBT), an UPLC‐MS/MS method has been developed and validated. The analytes, BBR and fenofibric acid (FBA, metabolite of FBT) and the internal standard, tetrahydropalmatine, were extracted with dichloromethane–diethyl ether (3:2, v/v) and separated on an Agilent Eclipse XDB C₁₈ column using a mobile phase composed of acetonitrile and water. With positive ion electrospray ionization, the analytes were monitored on a triple quadrupole mass spectrometer in multiple reaction monitoring mode. Linear calibration curves were obtained over the concentration ranges of 0.1–100.0 ng/mL for BBR and 10.0–50,000.0 ng/mL for FBA. For BBR and FBA, the intra‐ and inter‐day precisions were <11.5 and 11.9%, respectively. The accuracy was within 11.7% and 11.3%. The mean recoveries of BBR at three concentrations of 0.2, 20.0, 80.0 ng/mL were >85.6%, and those of FBA at three concentrations of 20.0, 2500.0, 40,000.0 ng/mL were >87.9%. Consequently, the proposed method was applied to the pharmacokinetic interaction study of FBT combined with BBR after oral administration in rats and was proved to be sensitive, specific and reliable to analyze BBR and FBA in biological samples simultaneously. Copyright © 2016 John Wiley & Sons, Ltd.     

Imatinib assay by high‐performance liquid chromatography in tandem mass spectrometry with solid‐phase extraction in human plasma

We have developed a method of liquid chromatography in tandem with mass spectrometry to monitor therapeutic levels of imatinib in plasma, a selective inhibitor of protein tyrosine kinase. After solid‐phase extraction of plasma samples, imatinib and its internal standard, imatinib‐D8, were eluted with Zorbax SB‐C₁₈ at 60 °C, under isocratic conditions through a mobile phase consisting of 4 mm ammonium formate, pH: 3.2 (solution A) and acetonitrile solution B. The flow rate was 0.8 mL/min with 55% solution A + 45% solution B. Imatinib was detected and quantified by mass spectrometry with electrospray ionization operating in selected‐reaction monitoring mode. The calibration curve was linear in the range 10–5000 ng/mL, the lower limit of quantitation being 10 ng/mL. The method was validated according to the recommendations of the Food and Drug Administration, including tests of matrix effect (bias < 10%) and recovery efficiency (>80 and <120%). The method is precise (coefficient of variance intra‐day <2% and inter‐day <7%), accurate (95–108%), sensitive and specific. It is a simple method with very fast recording time (1.2 min) that is applicable to clinical practice. This will permit improvement of the pharmacological treatment of patients. Copyright © 2012 John Wiley & Sons, Ltd.     

Development of rapid and high‐throughput LC–MS/MS method for quantification of olprinone in rabbit plasma

A simple, highly sensitive and rapid method for quantification of olprinone (phosphodiesterase 3 inhibitor) in rabbit plasma using liquid chromatography–tandem mass spectrometry with electrospray was developed. An aliquot of 50 μL of plasma sample was cleaned up and extracted using Ostro? 96‐well plate followed by dilution. Chromatographic separation of olprinone and olprinone‐d3 was carried out on a CORTECS^® T3 column within 3 min. Detection was achieved using a triple quadrupole mass spectrometer employing electrospray ionization operated in positive ion multiple reaction monitoring mode using the transitions m/z 251.07 → m/z 155.06 and m/z 254.21 → m/z 158.10 for olprinone and olprinone‐d3, respectively. The method was validated according to US Food and Drug Administration guideline for bioanalytical methods, and showed excellent linearity in the range 10.0–2000.0 ng/mL with coefficient of determination >0.99. The intra‐ and inter‐day precisions (CV) were <5.1% and the accuracies were within the range 99.7–103.2% at all quality control concentrations. Furthermore, olprinone was stable under various stability conditions. The developed method was used for quantification of olprinone in rabbit plasma after its intravenous administration at the dose of 1 mg/kg in order to better understand the metabolism of olprinone in a rabbit model of lung injury.     

Determination of d‐limonene in mice plasma and tissues by a new GC–MS/MS method: Comparison of the pharmacokinetics and tissue distribution by oral and inhalation administration in mice

The aim of the present study was to develop a method based on gas chromatography–tandem mass spectrometry (GC–MS/MS) to determine and quantify the d ‐limonene in mouse plasma and tissue samples. This new method was validated for the quantification of d ‐limonene with the linearity ranges 1.0–1000.0 ng/mL (r² > 0.9952) for plasma samples and 5.0–5000.0 ng/g (r² > 0.9940) for tissue samples. The intra‐ and inter‐day assay of precisions in plasma and tissues were <13.4% and the accuracies were within 91.1–105.8%. In the oral/inhalation administration pharmacokinetics and tissue distribution studies, the main pharmacokinetic parameters were the peak concentration = (97.150 ± 34.450)/(4336.415 ± 1142.418) ng/mL, the area under the curve = (162.828± 27.447)/(2085.721 ± 547.787) h ng/mL and the half‐life = (3.196 ± 0.825)/(0.989 ± 0.095) h. The tissue distribution of d ‐limonene in mice after oral/inhalation administration demonstrated a decreasing tendency in different tissues (liver > kidney > heart > lung > spleen).     

Simultaneous determination of plasma nicotine and cotinine by UHPLC–MS/MS in C57BL/6 mice and its application in a pharmacokinetic study

Plasma concentrations of nicotine and its active metabolite cotinine are highly correlated with its biological effects. A UHPLC–MS/MS method was developed, validated and applied for nicotine and cotinine analysis in mice plasma. Chromatographic separation was achieved on a BEH HILIC column using acetonitrile (0.1% formic acid) and 10 mm ammonium formate as mobile phase. The gradient elution was performed at 0.4 mL/min with a run time of 3.6 min. The quantitative ion transition was m/z 163.1 > 130.0 for nicotine, m/z 177.1 > 80.0 for cotinine and m/z 167.1 > 134.0 for nicotine‐D₄ (internal standard, IS). For both nicotine and cotinine, the calibration range was 5–500 ng/mL with 5 ng/mL as the lower limit of quantitation, and the intra‐ and inter‐day bias and imprecision were ?4.61–12.00% and <11.12%. The IS normalized recovery was 90.62–98.95% for nicotine and 89.18–101.53% for cotinine, and the IS normalized matrix factor was 106.00–116.44% for nicotine and 100.34–109.85% for cotinine. Both nicotine and cotinine were stable under conventional storage conditions. The validated method has been applied to a pharmacokinetic study in mice to calculate the pharmacokinetic parameters for both analytes.     

Development and validation of a simple and sensitive high‐resolution LC/MS method for determination of PF‐04620110 in dog plasma: Application to a pharmacokinetic study

In this study, a more sensitive and reliable quantitative method based on ultra‐high performance liquid chromatography coupled with Q‐Exactive‐Orbitrap‐MS in full‐mass scan was developed and validated for the determination of PF‐04620110 in dog plasma. After protein precipitation with acetonitrile, the sample separations were carried out on an Acquity BEH C₁₈ column with 1 mm ammonium acetate in water and acetonitrile containing 0.1% acetic acid as mobile phase, at a flow rate of 0.4 mL/min. The assay showed excellent linearity over the concentration range of 1–2000 ng/mL with correlation coefficient >0.9980 (r > 0.9980). The LLOQ was 1 ng/mL. The inter‐ and intra‐day precision (RSD, %) was within 9.69% while the accuracy (RE, %) was in the range of ?8.59–11.24%. The extraction recovery was >85.37% and the assay was free of matrix effects. PF‐04620110 was demonstrated to be stable under various processing and handing conditions. The validated method was successfully applied to the pharmacokinetic study of PF‐04620110 in dogs and the results revealed that PF‐04620110 was slowly eliminated from plasma with a clearance of 60.81 ± 7.11 mL/h/kg for intravenous administration and 81.44 ± 25.79 mL/h/kg for oral administration. The oral bioavailability was determined to be 77.89% in dogs.     

Development and validation of a liquid chromatography–tandem mass spectrometry method for topotecan determination in beagle dog plasma and its application in a bioequivalence study

Topotecan (TPT) is an important anti‐cancer drug that inhibits topoisomerase I. A sensitive and robust liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method that potentially determines TPT in beagle dog plasma is needed for a bioequivalence study of TPT formulations. We developed and validated LC‐MS/MS to evaluate TPT in beagle dog plasma in terms of specificity, linearity, precision, accuracy, stability, extraction recovery and matrix effect. Plasma samples were treated with an Ostro^TM sorbent plate (a robust and effective tool) to eliminate phospholipids and proteins before analysis. TPT and camptothecin (internal standard) were separated on an Acquity UPLC BEH C₁₈ column (1.7 µm, 2.1 × 50 mm) with 0.1% formic acid and methanol as the mobile phase at a flow rate of 0.25 mL/min. TPT was analyzed using positive ion electrospray ionization in multiple‐reaction monitoring mode. The obtained lower limit of quantitation was 1 ng/mL (signal‐to‐noise ratio > 10). The standard calibration curve for TPT was linear (correlation coefficient > 0.99) at the concentration range of 1–400 ng/mL. The intra‐day and inter‐day precision, accuracy, stability, extraction recovery and matrix effect of TPT were within the acceptable limits. The validated method was successfully applied in a bioequivalence study of TPT in healthy beagle dogs. Copyright © 2013 John Wiley & Sons, Ltd.     

LC–MS/MS method with chemical derivatization for quantitation of L‐threonate in human plasma

An LC–MS/MS‐based bioanalytical method has been developed to measure the concentration of L‐threonate at its endogenous level in human plasma. Following isotope dilution and protein precipitation, the samples were acetylated and chromatographed under reversed‐phase conditions for baseline separation of the derivatized L‐threonate and its stereoisomer D‐erythronate. The method was assessed by a fit‐for‐purpose validation with a calibration range from 100 to 10,000 ng/mL. The intra‐run coefficients of variation (CVs) were <3.6% and the inter‐run CV was 3.2% for the QC samples at endogenous level. At the lower limit of quantitation, the intra‐run CV was 6.1% and the average inaccuracy was ?1.4%. This method provides an efficient and reliable quantitation of L‐threonate and could be useful to certain biomarker investigators.     

Low dose aspirin estimation: an application to a human pharmacokinetic study

Low dose to very high dose aspirin is used to prevent heart attack. We have developed and validated a sensitive and robust method that could detect low levels of aspirin and salicylic acid in plasma and also a novel sample collection procedure to carry out sample preparation at room temperature. The total run time was 3.00 min; the developed method was validated in human plasma with a lower limit of quantitation of 0.99 ng/mL for aspirin and 2.01 ng/mL for salicylic acid. A linear response function was established for the range of concentrations 0.99–756.20 ng/mL (r > 0.998) for aspirin and 2.01–2486.86 ng/mL for salicylic acid. The intra‐ and inter‐day precision values for aspirin and salicylic acid met the acceptance as per FDA guidelines. The developed assay method was applied to an oral pharmacokinetic study in humans. Copyright © 2012 John Wiley & Sons, Ltd.     

Supported liquid extraction in combination with LC‐MS/MS for high‐throughput quantitative analysis of hydrocortisone in mouse serum

A high‐throughput LC–MS/MS bioanalytical method was developed and validated for the determination of hydrocortisone in mouse serum via supported liquid extraction (SLE) in a 96‐well plate format. Although sample extracts from SLE result in similar matrix effects compared with conventional liquid–liquid extraction (LLE), greater analyte extraction recovery and much higher analysis throughput for the quantitative analysis of hydrocortisone in mouse serum were obtained. The current LC‐MS/MS method was validated for a concentration range of 2.00–2000 ng/mL for hydrocortisone using a 0.100 mL volume of mouse serum. The intra‐ and inter‐day precision and accuracy of the quality control samples at low, medium and high concentration levels showed ≤12.9% CV and ?3.4–6.2% bias for the analyte in mouse serum. Copyright © 2009 John Wiley & Sons, Ltd.     

LC–MS/MS method for simultaneous determination of serum p‐cresyl sulfate and indoxyl sulfate in patients undergoing peritoneal dialysis

p‐Cresol sulfate (pCS) and indoxyl sulfate (IS) are protein‐bound uremic toxins that accumulate in patients with chronic kidney disease (CKD). They are closely associated with the mortality rate of CKD and morbidity of cardiovascular disease. In the present study, we established a rapid method for determination of pCS and IS by HPLC‐MS/MS in serum samples from 205 CKD patients undergoing peritoneal dialysis. In brief, serum was extracted by acetonitrile and spiked with hydrochlorothiazide. The prepared sample was eluted through HPLC column (Agilent Zorbax SB‐C₁₈, 3.5 μm, 2.1 × 100 mm) with a mobile phase of acetonitrile and 10 mm ammonium acetate solution (10:90, v/v) for subsequent detection of pCS and IS by MS/MS. The linearity ranged from 50 to 10,000 ng/mL for pCS (r > 0.99), and from 500 to 10,000 ng/mL for IS (r > 0.99). The lower limit of quantification was 50 ng/mL for pCS, and 500 ng/mL for IS. Relative standard deviation (RSD) of intra‐ and inter‐day precision was within ±15%. The results showed that pCS and IS levels were partially correlated with renal function in CKD patients, and IS was directly related to serum creatinine and estimated glomerular filtration rate.     

Quantitative determination of metformin,glyburide and its metabolites in plasma and urine of pregnant patients by LC‐MS/MS

This report describes the development and validation of an LC‐MS/MS method for the quantitative determination of glyburide (GLB), its five metabolites (M1, M2a, M2b, M3 and M4) and metformin (MET) in plasma and urine of pregnant patients under treatment with a combination of the two medications. The extraction recovery of the analytes from plasma samples was 87–99%, and that from urine samples was 85–95%. The differences in retention times among the analytes and the wide range of the concentrations of the medications and their metabolites in plasma and urine patient samples required the development of three LC methods. The lower limit of quantitation (LLOQ) of the analytes in plasma samples was as follows: GLB, 1.02 ng/mL; its five metabolites, 0.100–0.113 ng/mL; and MET, 4.95 ng/mL. The LLOQ in urine samples was 0.0594 ng/mL for GLB, 0.984–1.02 ng/mL for its five metabolites and 30.0 µg/mL for MET. The relative deviation of this method was <14% for intra‐day and inter‐day assays in plasma and urine samples, and the accuracy was 86–114% in plasma, and 94–105% in urine. The method described in this report was successfully utilized for determining the concentrations of the two medications in patient plasma and urine. Copyright © 2014 John Wiley & Sons, Ltd.