Rapid and sensitive method for simultaneous determination of citalopram with antihistamines by liquid chromatography.

A highly sensitive liquid chromatographic method with UV detection has been developed for simultaneous determination of citalopram, levocetirizine and loratadine in bulk drug, pharmaceutical formulation and human serum at 230nm employing 80:20 v/v methanol-water as mobile phase with pH3.5, adjusting flow rate of 1.0mL.min-1. Separation was achieved on Shimadzu Shim-pack CLC-ODS (M) 25M column within the linear range of 0.4-12.5, 0.8-25 and 0.8-25µg.mL-1 with R2 >0.998 and detection limit 7.75, 3.35 and 10.26ng.mL-1respectively. ICH guidelines were followed for validation showing 0.22-1.76, 0.06-1.83 and 0.22-2.11% RSD. The recovery of analytes in tablets and serum was found to be in acceptable range. The method was fruitfully employed for the determination of studied analyte in pharmaceutical formulation and human serum.

Effect of taste masking technology on fast dissolving oral film: dissolution rate and bioavailability.

Fast dissolving oral film is a stamp-style, drug-loaded polymer film with rapid disintegration and dissolution. This new kind of drug delivery system requires effective taste masking technology. Suspension intermediate and liposome intermediate were prepared, respectively, for the formulation of two kinds of fast dissolving oral films with the aim of studying the effect of taste masking technology on the bioavailability of oral films. Loratadine was selected as the model drug. The surface pH of the films was close to neutral, avoiding oral mucosal irritation or side effects. The thickness of a 2 cm × 2 cm suspension oral film containing 10 mg of loratadine was 100 µm. Electron microscope analysis showed that liposomes were spherical before and after re-dissolution, and drugs with obvious bitterness could be masked by the encapsulation of liposomes. Dissolution of the two films was superior to that of the commercial tablets. Rat pharmacokinetic experiments showed that the oral bioavailability of the suspension film was significantly higher than that of the commercial tablets, and the relative bioavailability of the suspension film was 175%. Liposomal film produced a certain amount of improvement in bioavailability, but lower than that of the suspension film.

D-Optimal mixture design optimization of an HPLC method for simultaneous determination of commonly used antihistaminic parent molecules and their active metabolites in human serum and urine.

This study describes a specific, precise, sensitive and accurate method for simultaneous determination of hydroxyzine, loratadine, terfenadine, rupatadine and their main active metabolites cetirizine, desloratadine and fexofenadine, in serum and urine using meclizine as an internal standard. Solid-phase extraction method for sample clean-up and preconcentration of analytes was carried out using Phenomenex Strata-X-C and Strata X polymeric cartridges. Chromatographic analysis was performed on a Phenomenex cyano (150 × 4.6 mm i.d., 5 µm) analytical column. A D-optimal mixture design methodology was used to evaluate the effect of changes in mobile phase compositions on dependent variables and optimization of the response of interest. The mixture design experiments were performed and results were analyzed. The region of ideal mobile phase composition consisting of acetonitrile-methanol-ammonium acetate buffer (40 mm; pH 3.8 adjusted with acetic acid): 18:36:46% v/v/v was identified by a graphical optimization technique using an overlay plot. While using this optimized condition all analytes were baseline resolved in <10 min. Solvent mixtures were delivered at 1.5 mL/min flow rate and analytes peaks were detected at 222 nm. The proposed bioanalytical method was validated according to US Food and Drug Administration guidelines. The proposed method was sensitive with detection limits of 0.06-0.15 µg/mL in serum and urine samples. Relative standard deviation for inter- and intra-day precision data was found to be <7%. The proposed method may find application in the determination of selected antihistaminic drugs in biological fluids.

Simultaneous determination of desloratadine and montelukast sodium using second-derivative synchronous fluorescence spectrometry enhanced by an organized medium with applications to tablets and human plasma.

A rapid, simple, and sensitive second-derivative synchronous fluorimetric method has been developed and validated for the simultaneous analysis of a binary mixture of desloratadine (DSL) and montelukast sodium (MKT) in their co-formulated tablets. The method is based on measurement of the synchronous fluorescence intensities of the two drugs in McIlvaine's buffer, pH 2.3, in the presence of carboxy methyl cellulose sodium (CMC) as a fluorescence enhancer at a constant wavelength difference (Δλ) of 160 nm. The presence of CMC enhanced the synchronous fluorescence intensity of DSL by 216% and that of MKT by 28%. A linear dependence of the concentration on the amplitude of the second derivative synchronous fluorescence spectra was achieved over the ranges of 0.10-2.00 and 0.20-2.00 µg/mL with limits of detection of 0.02 and 0.03, and limits of quantification of 0.05 and 0.10 µg/mL for DSL and MKT, respectively. The proposed method was successfully applied for the determination of the studied compounds in laboratory-prepared mixtures and tablets. The results were in good agreement with those obtained with the comparison method. The high sensitivity attained by the proposed method allowed the determination of MKT in spiked human plasma with average % recovery of 100.11 ± 2.44 (n = 3).

[Determination of Desloratadine and Its Metabolite 3-OH Desloratadine in Human Plasma by LC-MS/MS].

OBJECTIVE: To develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of desloratadine and its metabolite 3-OH desloratadine in human plasma. METHODS: 24 healthy male volunteers received a single oral dose of 5 mg desloratadine tablets in a randomized crossover bioequivalence study with two preparations of tablets. Serial plasma samples were taken and analyzed by the LC-MS/MS method. The pharmacokinetic parameters of the two preparations were calculated and compared statistically to evaluate their bioequivalence using Winnonlin 6. 3. RESULTS: The calibration curves of desloratadine and 3-OH desloratadine were both linear over the concentration range of 0. 050-6. 0 ng/mL, with intra-batch and inter-batch relative standard deviations less than 15%. The 90% confidence intervals (CIs) of peak concentration (Cmax) area under the curve (AUC)0t and AUC0-∞ of desloratadine and 3-OH desloratadine all resided within the bioequivalence limit 80%-125%. No significant difference in peak time (Tmax) was demonstrated between the two preparations. CONCLUSION: The LC-MS/MS method can be used for simultaneous determination of desloratadine and 3-OH desloratadine in human plasma, which has been successfully applied-to a bioequivalence study.

Prevalence of desloratadine poor metabolizer phenotype in healthy Jordanian males.

PURPOSE: To study the prevalence of desloratadine slow metabolizer phenotype among a group of healthy Jordanian male volunteers. METHODS: A total of 62 healthy Jordanian male volunteers were included in this study. A single 5 mg desloratadine oral tablet was given and blood samples were taken to determine the desloratadine and 3-hydroxydesloratadine (3-OH-desloratadine) concentrations using a specific liquid chromatography-mass spectrometric method (LC/MS/MS). The determination of pharmacokinetic parameters of all the individuals was determined by using Kinetica® program version 4.1. Poor metabolizers or slow metabolizers of desloratadine were determined as individuals having a 3-OH-desloratadine to desloratadine exposure ratio lower than 10% or a desloratadine half-life ≥ 50 h. RESULTS: Among the 62 volunteers who participated in the study there were only two volunteers who were labeled as desloratadine slow metabolizers, giving a prevalence of 3.2%. The maximum plasma concentrations (C(max)) were similar in the extensive and slow metabolizers groups but a longer time (t(max)) was needed to achieve this concentration in one of the volunteers who was a desloratadine slow metabolizer. CONCLUSION: The incidence of the poor metabolizer phenotype of desloratadine in the Jordanian population studied is similar to certain ethnic groups (e.g. Asian, Caucasians and Hispanic); however, it is lower than other populations (e.g. American Indians and Black).

[Comparative pharmacokinetics of antigrippin-maximum administered in capsules and powder for preparing solutions].

Comparative pharmacokinetics of anti-influenza drug composition Antigrippin-maximum administered in capsules and a powder for preparing solutions has been studied after single administraton in a group of 18 healthy volunteers. Both preparations [manufactured by the Antiviral Research and Production Corporation (St Petersbutg) contain 6 active components, including paracetamol, rimantadine, loratadine, ascorbic acid, calcium gluconate, and rutoside in equal amounts. The concentrations of unchanged paracetamol, rimantadine, and loratadine in the blood plasma were degtermined by HPLC with mass-spectrometric and UV detection. The pharmacokinetic parameters of allindicated active components exhibited no detectable distinctions, except for the time to attaining maximum concentration ofparacetamol and the value of the maximum concentration of loratadine.

A new open tubular capillary microextraction and sweeping for the analysis of super low concentration of hydrophobic compounds.

A sample pre-concentration method based on the in-line coupling of in-tube solid-phase microextraction and electrophoretic sweeping was developed for the analysis of hydrophobic compounds. The sample pre-concentration and electrophoretic separation processes were simply and sequentially carried out with a (35%-phenyl)-methylpolysiloxane-coated capillary. The developed method was validated and applied to enrich and separate several pharmaceuticals including loratadine, indomethacin, ibuprofen and doxazosin. Several parameters of microextration were investigated such as temperature, pH and eluant. And the concentration of microemulsion that influences separation efficiency and microextraction efficiency were also studied. Central composite design was applied for the optimization of sampling flow rate and sampling time that interact in a very complex way with each other. The precision, sensitivity and recovery of the method were investigated. Under the optimal conditions, the maximum enrichment factors for loratadine, indomethacin, ibuprofen and doxazosin in aqueous solutions are 1355, 571, 523 and 318, respectively. In addition, the developed method was applied to determine loratadine in rabbit blood sample.

Simultaneous determination of rupatadine and its metabolite desloratadine in human plasma by a sensitive LC-MS/MS method: application to the pharmacokinetic study in healthy Chinese volunteers.

A sensitive liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for simultaneous determination of rupatadine and its metabolite desloratadine in human plasma. After the addition of diphenhydramine, the internal standard (IS), plasma samples were extracted with a mixture of methyl tert-butyl ether and n-hexane (1:1, v/v). The analysis was performed on a Ultimate AQ-C18 (4.6mm x 100mm, 5microm) column using a mobile phase consisting of a 80/20 mixture of methanol/water containing 0.0005% formic acid pumped at 0.3mlmin(-1). The analytes and the IS were detected in positive ionization mode and monitoring their precursor-->product ion combinations of m/z 416-->309, 311-->259, and 256-->167, respectively, in multiple reaction monitoring mode. The linear ranges of the assay were 0.1-50 and 0.1-20ngml(-1) for rupatadine and desloratadine, respectively. The lower limits of reliable quantification for both rupatadine and desloratadine were 0.1ngml(-1), which offered high sensitivity and selectivity. The within- and between-run precision was less than 7.2%. The accuracy ranged from -9.2% to +6.4% and -7.2% to +7.2% for rupatadine and desloratadine in quality control samples at three levels, respectively. The method has been successfully applied to a pharmacokinetic study of rupatadine and its major metabolite after oral administration of 10, 20 and 40mg rupatadine tablets to healthy Chinese volunteers.

Developing a High-performance Liquid Chromatography Method for Simultaneous Determination of Loratadine and its Metabolite Desloratadine in Human Plasma.

BACKGROUND: Allergic diseases are considered as the major burden on public health with increased prevalence globally. Histamine H1-receptor antagonists are the foremost commonly used drugs in the treatment of allergic disorders. The target drug in this study, loratadine, belongs to this class of drugs and its biometabolite desloratadine which is also a non-sedating H1 receptor antagonist with anti-histaminic activity being 2.5 to 4 times greater than loratadine. This study aimed to develop and validate a novel isocratic Reversed-phase High-Performance Liquid Chromatography (RP-HPLC) method for rapid and simultaneous separation and determination of loratadine and its metabolite, desloratadine in human plasma. METHODS: The drug extraction method from plasma was based on protein precipitation technique. The separation was carried out on a Thermo Scientific BDS Hypersil C18 column (5µm, 250 x 4.60 mm) in a mobile phase of MeOH: 0.025M KH2PO4 adjusted to pH 3.50 using orthophosphoric acid (85: 15, v/v) at an ambient temperature. The flow rate was maintained at 1 mL/min and maximum absorption was measured using the PDA detector at 248 nm. RESULTS: The retention times of loratadine and desloratadine in plasma samples were recorded to be 4.10 and 5.08 minutes, respectively, indicating a short analysis time. Limits of detection were found to be 1.80 and 1.97 ng/mL for loratadine and desloratadine, respectively, showing a high degree of sensitivity of the method. The method was then validated according to FDA guidelines for the determination of the two analytes in human plasma. CONCLUSION: The results obtained indicate that the proposed method is rapid, sensitive in the nanogram range, accurate, selective, robust and reproducible compared to other reported methods.

Pharmacokinetic and safety profile of rupatadine when coadministered with azithromycin at steady-state levels: a randomized, open-label, two-way, crossover, Phase I study.

BACKGROUND: Rupatadine is an oral active antihistamine and platelet-activating factor antagonist indicated for the management of allergic rhinitis and chronic urticaria in Europe. OBJECTIVE: The purpose of this study was to describe the effect of the concomitant administration of azithromycin and rupatadine on the pharmacokinetics of rupatadine and its metabolites after repeated doses. METHODS: This was a multiple-dose, randomized, open-label, 2-way, crossover, Phase I study in which healthy male and female volunteers received rupatadine 10 mg once a day for 6 days either alone or with azithromycin 500 mg on day 2 and 250 mg from day 3 to day 6. Treatments were administered after a fasting period of 10 hours with 240 mL of water, and fasting conditions were kept until 3 hours postmedication. A washout period of at least 21 days between the 2 active periods was observed. Blood samples were collected and plasma concentrations of rupatadine and its metabolites desloratadine and 3-hydroxydesloratadine were determined by liquid chromatography tandem mass spectrometry. Tolerability was based on the recording of adverse events (AEs), physical examination, electrocardiograms, and laboratory screen controls at baseline and the final study visit. RESULTS: Twenty-four healthy volunteers (15 males, 9 females; mean [SD] age, 25.67 [5.58] years; weight, 65.96 [8.57] kg) completed the study. Except for maximum observed concentration during a dosing interval (Cmax,ss) of 3-hydroxydesloratadine, on average, there were no statistically significant differences in mean plasma concentrations in any of the main pharmacokinetic parameters of rupatadine, desloratadine, and 3-hydroxydesloratadine when administered in combination with azithromycin or alone. The Cmax,ss ratio was 111 (90% CI, 91-136) and area under the plasma concentration-time curve during a dosing interval (AUC0-tau) ratio had a value of 103 (90% CI, 91-117). The corresponding ratios for the rupatadine metabolites were 109 (90% CI, 100-120) for Cmax,ss and 103 (90% CI, 96-110) for AUC0-tau for desloratadine and 109 (90% CI, 103-115) for Cmax,ss and 104 (90% CI, 100-108) for AUC0-tau for 3-hydroxydesloratadine. Point estimates for Cmax,ss ratios using paired data were 111% for rupatadine, 109% for desloratadine, and 109% for 3-hydroxydesloratadine. The 90% CIs were included in the interval 80% to 125% for desloratadine and 3-hydroxydesloratadine, whereas 90% CI for rupatadine was shifted to the right of the interval used for comparing bioavailability of the drugs. A total of 5 subjects reported 9 AEs; 5 of these were thought to be related to the drug administration and all were categorized as mild or moderate. The reported AEs were somnolence (1/24 in the rupatadine group and 1/24 in the rupatadine plus azithromycin group), diarrhea (1/24 in the rupatadine plus azithromycin group), and gastric discomfort (2/24 in the rupatadine plus azithromycin group). Four AEs were considered not to be related (2 episodes of headache, 1 anemia, 1 cheilitis). All were resolved spontaneously. No serious AEs were reported. CONCLUSIONS: The results of this study in these healthy volunteers found no significant differences in pharmacokinetic parameters other than Cmax,ss of 3-hydroxydesloratadine between rupatadine 10 mg administered alone or with azithromycin 500 mg on day 2 and 250 mg from day 3 to day 6. The administration of rupatadine compared with rupatadine plus azithromycin met the regulatory definition of bioequivalence in terms of exposure and rate parameters; however, Cmax,ss of rupatadine was outside the conventional confidence interval.

Comparison of hydrophilic interaction and reversed-phase liquid chromatography coupled with tandem mass spectrometric detection for the determination of three pharmaceuticals in human plasma.

In the present study, hydrophilic interaction liquid chromatography (HILIC) and reversed-phase liquid chromatography (RPLC) combined with tandem mass spectrometric detection (MS/MS) were evaluated and compared for the determination of donepezil, cetirizine and loratadine in human plasma, in terms of sensitivity and sample preparation procedure. A retention study for the above compounds of various polarities was performed, using both C(18) and silica columns, with several aqueous-organic mobile phase ratios, in order to investigate their retention mechanism profile under HILIC and RPLC. Both chromatographic conditions were compared for chromatographic analysis of plasma samples processed with a liquid-liquid extraction (LLE) method for donepezil determination, resulting in significantly higher sensitivity under HILIC. Furthermore, HILIC and RPLC were compared for direct injection, and novel methods including LLE, solid-phase extraction and protein precipitation protocols were developed. Direct injection technique significantly reduced sample preparation time, increasing at the same time method sensitivity. The current study contributes to broadening the range of analyzable compounds by HILIC-MS/MS to molecules of medium polarity.

Antihistaminic effects of rupatadine and PKPD modelling.

Rupatadine is a new oral antihistaminic agent used for the management of allergic inflammatory conditions, such as rhinitis and chronic urticaria. The aim of the present study was to develop a population pharmacokinetic/pharmacodynamic (PKPD) model for the description of the effect of rupatadine and one of its active metabolites, desloratadine, on the histamine-induced flare reaction and to predict the response to treatment after repeated administrations of rupatadine. Both rupatadine and desloratadine were characterized by two-compartmental kinetics. For both compounds, covariates sex and weight had a significant effect on several parameters. The pharmacodynamics were described by an indirect model for the inhibition of flare formation that accounted for the contribution of both rupatadine and desloratadine to the antihistaminic effect. The final PKPD model adequately described the original data. The simulated response after repeated once-daily administrations of 10 mg rupatadine showed a significant and maintained antihistaminic effect over time, between two consecutive dosing intervals.

Influence of food on the oral bioavailability of rupatadine tablets in healthy volunteers: a single-dose, randomized, open-label, two-way crossover study.

BACKGROUND: Rupatadine is an oral active antihistamine for the management of diseases with allergic inflammatory conditions, such as perennial and seasonal rhinitis and chronic idiopathic urticaria. Oral rupatadine has been approved for the treatment of allergic rhinitis and chronic urticaria in adults and adolescents in several European countries. OBJECTIVE: The purpose of this study was to describe the effect of the concomitant intake of food on the pharmacokinetic profile and bioavailability of a single dose of rupatadine. METHODS: This was a single-dose, randomized, open-label, 2-way crossover study in which healthy male and female volunteers received a single, 20-mg oral dose of rupatadine under fed and fasting conditions. Blood samples were collected and plasma concentrations of rupatadine and its active metabolites desloratadine and 3-hydroxydesloratadine were determined by liquid chromatography tandem mass spectrometry. Tolerability was based on the recording of adverse events (AEs), physical examinations, electrocardiograms, and laboratory tolerability tests immediately before each treatment period and at the final visit of the study. RESULTS: Twenty-four volunteers (12 males; mean [SD] age, 25.4 [5.3] years [range, 18-34 years]; mean [SD] weight, 71.2 [4.3] kg [range, 64-77 kg]; 12 females; mean [SD] age, 26.8 [6.5] years [range, 18-38 years]; mean [SD] weight, 58.4 [6.8] kg, [range 50-69 kg]) were enrolled and randomized with equal distribution of sex. A significant increase in AUC from drug administration to the final quantifiable sample (AUC(0-t)) and AUC from drug administration to infinity (AUC(0-infinity)) values of rupatadine was seen under fed conditions without affecting C(max). The ratios (90% CI) of the mean log-transformed AUC(0-t) and AUC(0-infinity) for rupatadine revealed a significant increase in AUC(0-t) (ratio 131%; 90% CI, 111%-154%) and AUC(0-infinity) (ratio 133%; 90% CI, 113%-156%), whereas C(max) remained unaltered (ratio 97%; 90% CI, 80%-116%). Plasma concentration-time profiles of desloratadine and 3-hydroxydesloratadine were similar with and without food, and no differences were seen for AUC(0-t), AUC(0-infinity), or C(max). Seven (28%) subjects reported > or =1 AE. All AEs were mild, resolved spontaneously, and did not affect the outcome of the study. CONCLUSIONS: The results of this study indicate that concomitant intake of food with a single 20-mg oral dose of rupatadine exhibits a significant increase in rupatadine bioavailability. Despite the absence of bioequivalence, the drug was well tolerated under fed and fasting conditions, and no major changes in severity and/or prevalence of AEs were reported.

Development and validation of high-throughput liquid chromatography-tandem mass spectrometric method for simultaneous quantification of loratadine and desloratadine in human plasma.

As a continuation of effort to improve our high flow on-line bioanalytical approach for high-throughput quantification of drugs and metabolites in plasma by high-throughput liquid chromatography tandem mass spectrometry (HTLC-MS/MS), we have developed a simple, sensitive and reliable method for simultaneous quantification of loratadine and desloratadine in human plasma. We have performed on-line coupling of extraction with Cyclone P 50 mm x 0.5 mm 50 microm HTLC column and chromatographic separation is performed with Zorbax XDB C18 50 mm x 2.1 mm 5 microm, followed by quantification with mass detector. The method is validated and showed good performances in terms of linearity, sensitivity, precision, accuracy and stability. A marked improvement in sample throughput efficiency is realized with this method and the proposed method will be useful for pharmacokinetic and/or bioequivalence studies.

Simultaneous determination of desloratadine and its active metabolite 3-hydroxydesloratadine in human plasma by LC/MS/MS and its application to pharmacokinetics and bioequivalence.

A rapid and simple liquid chromatographic-tandem mass spectrometric (LC/MS/MS) method was developed and validated for the simultaneous determination of desloratadine and its active metabolite 3-hydroxydesloratadine concentrations in human plasma. After liquid-liquid extraction with ethyl ether for sample preparation, the chromatographic separation was achieved on a CAPCELL PAK C18 column (50 mm x 2.0mm, 5 microm, Shiseido). [(2)H(4)]desloratadine and [(2)H(4)]3-OH desloratadine were used as internal standards. A mobile phase consisted of 5mM ammonium formate in water, methanol and acetonitrile (50:30:20). Detection was by positive ion electrospray tandem mass spectrometry on a Sciex API3000. A quadratic regression (weighted 1/concentration) gave the best fit for calibration curves over the concentration range 0.05-10 ng/mL for both desloratadine and 3-OH desloratadine. The method was shown to be accurate, rapid and sufficiently sensitive to be successfully applied to a pharmacokinetic and bioequivalent study.

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.

Quantitative determination of galantamine in human plasma by sensitive liquid chromatography-tandem mass spectrometry using loratadine as an internal standard.

A simple, rapid, sensitive, and selective liquid chromatography-tandem mass spectrometry method is developed and validated for the quantitation of galantamine, an acetylcholinesterase inhibitor in human plasma, using a commercially available compound, loratadine, as the internal standard. Following liquid-liquid extraction, the analytes are separated using an isocratic mobile phase on a reverse-phase C18 column and analyzed by mass spectrometry in the multiple reaction monitoring mode using the respective (M+H)+ ions, m/z 288 to 213 for galantamine and m/z 383 and 337 for the internal standard. The assay exhibit a linear dynamic range of 0.5-100 ng/mL for galantamine in human plasma. The lower limit of quantitation is 0.5 ng/mL, with a relative standard deviation of less than 8%. Acceptable precision and accuracy are obtained for concentrations over the standard curve range. A run time of 2.5 min for each sample makes it possible to analyze more than 400 human plasma samples per day. The validated method is successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability, or bioequivalence studies.

Orthogonal extraction/chromatography and UPLC, two powerful new techniques for bioanalytical quantitation of desloratadine and 3-hydroxydesloratadine at 25 pg/mL.

Validation of the bioanalytical method for determination of desloratadine and 3-hydroxydesloratadine was conducted using ultra high pressure liquid chromatography (UPLC) in conjunction with mix mode solid phase extraction. The dynamic range of the assay was from 0.025 ng/mL to 10 ng/mL using 96-well solid phase extraction. On an UPLC system, the inter-run accuracy was better than 94.7% for desloratadine (n = 18) and 94.0% for 3-hydroxydesloratadine (n = 18). The between-run precision (%CV) ranged from 2.6% to 9.8% for desloratadine (n = 18) and 3.1% to 11.1% for 3-hydroxydesloratadine (n = 18). The limit of quantitation represented 0.478 pg and 0.525 pg of extracted material injected on-column for desloratadine and 3-hydroxydesloratadine, respectively. The total run time was slightly over 2 min per sample. The approach of orthogonal extraction/chromatography and UPLC significantly improves assay performance while also increasing sample throughput for drug development studies.

LC-ESI-MS/MS estimation of loratadine-loaded self-nanoemulsifying drug delivery systems in rat plasma: Pharmacokinetic evaluation and computer simulations by GastroPlus™.

A rapid, sensitive, and accurate bioanalytical method was established for the quantitation and pharmacokinetic investigation of loratadine (LTD) in rat plasma by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS/MS) using loratadine-d5 as internal standard (ISTD). The analyte and ISTD were extracted by solid-phase extraction and chromatographic separation was achieved on Gemini NX- Reverse Phase C18 (50 × 4.6mm; 5 µ) using mobile phase mixture of 5mM ammonium formate buffer in water (pH 3.5 ± 0.1 with formic acid), and acetonitrile (20:80 v/v), at a flow rate of 0.400 mL/min with injection volume of 10 µL. LTD and ISTD were detected at m/z 383.3 → 337.4 and 388.4 → 337.3 with retention time of 2.62 and 2.59 min, respectively. High sensitivity (1.0 ng/mL) was achieved using small volume of rat plasma (20 µL) and the method was validated over a linearity range of 1.05-405.41 ng/mL with high correlation coefficient (r = 0.9998). The extraction method displayed a mean process efficiency of 63.25 and 65.47% for LTD and ISTD, respectively. The validated method when successfully applied for quantification of LTD in rat plasma revealed enhanced bioavailability of orally administered LTD-loaded self-nanoemulsifying drug delivery system (SNEDDS) (Cmax, 466.65 ± 18.94 ng/mL and AUC0-t 633.00 ± 12.44 ng-h/mL) over LTD-suspension (Cmax, 104.75 ± 2.87 ng/mL and AUC0-t 287.00 ± 9.11 ng-h/mL). The in vivo-in silico prediction by the GastroPlus™ software showed good prediction accuracy for LTD-SNEDDS (fold error < 2). The Loo-Reigelman method (2-compartment) presented best model-fitting indicating adequate in vitro-in vivo correlations. Conclusively, the developed sensitive analytical method displayed enhanced systemic availability of LTD-SNEDDS, and the in vivo in silico approach revealed sufficiently good GI simulation.