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Combined therapy for HIV treatment shows superior efficacy in comparison to single therapy. Furthermore, the separation and determination of the combined dosage forms hold a significant place in the pharmaceutical industry. Not only reverse phase high-performance liquid chromatography (HPLC) but also hydrophilic interaction liquid chromatography (HILIC) can be used for these purposes. Contrary to conventional RP systems, HILIC may be an alternative for the analysis of polar substances. The aim of this study was the step-by-step development of a simple, rapid, and reliable method for the simultaneous determination of antiviral compounds from their marketed formulation (Trizivir). In order to achieve this goal, various mobile phase systems, buffer types, and concentrations were prepared to provide an appropriate separation. Different types of columns were tested to find the best resolution and high efficiency for the studied compounds. The proposed method provided a simple procedure for the simultaneous analysis of abacavir, lamivudine, and zidovudine in their pharmaceutical preparation within approximately 2 min using the conventional HPLC system. The developed method was fully validated according to the International Council for Harmonisation guidelines from the viewpoint of selectivity, sensitivity, precision, accuracy, linearity, limit of detection, and quantification.

In this study, a novel, fast, selective, and sensitive molecularly imprinted polymer (MIP)-based electrochemical sensor was developed to determine axitinib (AXI) at low concentrations in pharmaceutical dosage forms and human serum. The newly developed MIP-based sensor (MIP@o-PD/GCE) was designed through electropolymerization of functional monomer o-phenylenediamine (o-PD) in the presence of a template molecule AXI, on a glassy carbon electrode (GCE) using cyclic voltammetry. Differential pulse voltammetry and electrochemical impedance spectroscopy (EIS) techniques were employed for removal and rebinding processes, optimization of conditions, as well as for performance evaluation of MIP@o-PD/GCE using [Fe(CN)6]3−/4– as the redox probe. Under the optimum experimental conditions, MIP@o-PD/GCE shows a linear response toward AXI in a range of 1 × 10−13 M − 1 × 10−12 M. The limit of the detection value of MIP@o-PD/GCE was found as 0.027 pM while the limit of the quantification was obtained as 0.089 pM, respectively. To demonstrate the applicability and validity of the developed sensor, it was successfully applied to tablet dosage form and human serum sample. The selectivity of the sensor was qualified by comparing the binding of AXI, erlotinib, dasatinib, nilotinib, and imatinib, which are similarly structured and in the same group of anticancer drugs. MIP@o-PD/GCE sensor showed a significant selectivity toward AXI. The non-imprinted polymer (NIP) based GCE was prepared and used to control the analytical performance of the MIP-based electrochemical sensor.

Combined drug therapy which is based on the co-administration of two or more drugs, have been used for a long time, to treat diseases. In this study, a simple, selective and rapid RP-LC method has been developed and validated for the sensitive and simultaneous determination of simvastatin (SMV) and ezetimibe (EZE) in fixed-dose combination tablets and in rabbit serum using a simple sample preparation procedure. The developed RPLC method for these lipid-lowering agents was completely validated and in the linear range of 0.05–50 µg mL− 1 EZE and 0.05–10 µg mL− 1 SMV. The calibration curves were obtained with limit of detection values of 0.013 µg mL− 1, 0.009 µg mL− 1—for EZE and SMV, respectively. The developed method was successfully applied to the analysis of EZE and SMV in fixed-dose combination tablets and in rabbit serum, and no interference was observed from any excipients and endogenous substances in the rabbit serum samples. Dissolution profiles of the pharmaceutical dosage form of these lipid-lowering agents were also studied.

Liquid chromatography (LC) coupled to an electrochemical (EC) detector is a complementary analytical tool compared to LC coupled with optical or mass spectrometry detectors (LC-MS). LC-EC can be applied to the determination of molecules difficult to be analyzed by other commercially available detectors. New EC detector design and new working electrode material have extended the scope of application in the field of pharmaceutical compounds analysis. Combining EC with LC-MS offers additional advantages compared to optical detectors in terms of drug stability and drug metabolism mimicry studies. Selected literature devoted to pharmacologically active compounds in their dosage forms, herbal drugs in natural products, drug residues in feed and/or in biological samples are reported in this review.

In this study, clopidogrel (CLP), which is an antiplatelet agent widely used in the prevention of ischemic stroke, was analyzed using functionalized multi-walled carbon nanotubes (fMWCNTs) and CdSe quantum dots (QDs) modified glassy carbon electrode. The dependence of intensities of currents and potential on pH, concentration, scan rate, nature of the buffer was further investigated. The oxidation process exhibited mixed diffusion under adsorption controlled process depending on pH. For the analytical application, adsorptive stripping differential pulse voltammetric (AdSDPV) technique was used and all operational parameters were optimized. The plot of peak current vs CLP concentration consisted of a linear segment in the concentration range between 2.0 × 10−6 M and 4.0 × 10−5 M and the detection limit (3σ) was obtained 7.55 × 10−8 M in pH 2.14 phosphate buffer solution. Moreover, in order to evaluate the analytical applicability of the proposed method, it was applied to the determination of CLP in serum samples with linear range of 2.5 × 10−6–1.5 × 10−5 M and the detection limit value of 2.99 × 10−7 M. Determination of CLP in tablet dosage form Atervix® was also proposed with acceptable recovery values.

In this study, an electrochemical sensing platform was prepared to determine regorafenib on multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrodes (GCE) by adsorptive stripping differential pulse voltammetry (AdsDPV). The electrooxidation of regorafenib was an irreversible reaction and governed by an adsorption process that is pH-dependent. According to the oxidation mechanism study, two electrons were required for electrochemical oxidation of regorafenib in 0.1 M H2SO4. The influence of temperature was studied to evaluate the kinetic and thermodynamic parameters using the cyclic voltammetry method in different temperature values. Using adsorptive stripping mode, a significant improvement in the response signal of regorafenib was registered on the surface of MWCNTs/GCE as compared to bare GCE. MWCNTs/GCE sensor was successfully used for the determination of regorafenib in a linear range between 5 × 10-7 M and 2.5 × 10-5 M (R2 = 0.998) with a limit of detection and limit of quantification values of 2.08 × 10-8 M and 6.93 × 10-8 M in 0.1 M H2SO4 solution. Additionally, for the evaluation of the applicability of the developed nanomaterial-modified sensor platform, it was applied to human serum samples and pharmaceutical tablet dosage forms with good recovery results.

Base to the interfacial adsorptive nature of granisetron (GRN) on platinum particles modified glassy carbon electrode (PtPs/GCE). A sensitive analytical method for trace analysis of GRN based on the adsorptive stripping technique has been developed. The application of a square wave mode for the stripping of adsorbed GRN has proved to be much more sensitive compared to differential pulse scan. A study of the variation in the peak current with solution variables such as pH, concentration of granisetron, possible interference, and instrumental variables, such as accumulation time and accumulation potential, has resulted in the optimization of the oxidation signal for analytical purposes. Under the optimized conditions, the square wave peak current showed two linear ranges of GRN concentration: 0.01–0.5 ?M and 0.5–25 ?M with correlation coefficients of 0.997 and 0.998, respectively. Nanomolar detection limit was obtained as 1.95 nM for the first linear range. Possible interferences by substances usually present in the pharmaceutical formulations were also evaluated. The proposed electrochemical procedure was successfully applied for the determination of GRN in pharmaceutical injection samples (SETRON® 3 mg/3 mL) with average recovery of 100.30%. © 2017 Elsevier B.V.

A novel sensor based on a modification of glassy carbon electrode (GCE) with NH2-functionalized multi walled carbon nano-tubes (NH(2)fMWCNTs) is reported and its applicability to the electrochemical sensing of Propafenone (PPF) demonstrated. The electrochemical catalytic activity was also utilized as a sensitive detection method for the investigation of the detailed redox mechanism of PFF using cyclic and and differential pulse voltammetry. The surface morphology of the sensor was investigated by SEM armed with EDX probe. Electrochemical impedance spectroscopy was employed as well to define the electron transfer capability of modified and bare electrodes. Key experimental and instrumental conditions related to electrochemical determination by cyclic, differential pulse, and square wave voltammetry, such as amount of modifier, pH, scan rate, accumulation time and potential were studied and optimized. The results have shown a significant enhancement of the peak current after modifying the electrode; the calibration curves of PPF offering good linearity from 0.1 to 10 mu M, limit of quantification (LOQ) being 0.03 mu M and limit of detection (LOD) 0.01 mu M, both when using DPV technique. The proposed sensor was successfully applied to the determination of PFF in dosage form without any special purification, separation or pre-treatment steps. The results of analyses obtained with the proposed sensor were satisfactory and fully statistically relevant. (C) 2019 Elsevier B.V. All rights reserved. Faculty of Chemical Technology, University of Pardubice; Faculty of Pharmacy, Ankara University Financial support from the Faculty of Chemical Technology, University of Pardubice and from Faculty of Pharmacy, Ankara University are gratefully acknowledged. WOS:000479328000062 2-s2.0-85067806253 PubMed: 31252310

In the proposed work, the simultaneous analysis of amlodipine–rosuvastatin and amlodipine–atorvastatin in their dosage forms was achieved. Simultaneous dissolution profiles of the amlodipine–rosuvastatin and amlodipine–atorvastatin tablets are realized using Apparatus II with a simple, accurate and precise RP-LC method. The mobile phase consisting of 0.2 % H3PO4 and pH 5:methanol:acetonitrile (46:27:27) was used. The samples of 10 µL were injected onto a Zorbax SB C18 (100 mm, 4.6 mm, 3.5 µm particle size) column with 1.2 µL min−1 flow rate. The samples were detected at 236 nm. By plotting peak area ratios vs. concentration, the linearity for amlodipine–rosuvastatin and amlodipine–atorvastatin was determined. With the developed RP-LC method, AML, ROS and ATOR were detected within the range of 0.25–10, 0.5–10 and 0.25–25 µg mL−1, respectively. LOD and LOQ values were also calculated as 0.028, 0.058, 0.021 and 0.095 µg mL−1, 0.195 µg mL−1, 0.070 µg mL−1 for AML, ROS and ATOR, respectively. System suitability tests parameters, such as capacity factor, selectivity to previous peak, selectivity to next peak, resolution to previous peak, resolution to next peak, tailing factor, theoretical number of plates, were performed and found coherent with the ICH guideline parameters. The proposed method has been extensively validated in terms of recovery, and recovery results were between 99 and 101 %. For proving the precision, between-day and within-day repeatability results of the method were proposed. The method can be used for the simultaneous determination of amlodipine–rosuvastatin and amlodipine–atorvastatin.

After oral administration, drug absorption from solid dosage forms depends on the release of the drug active compounds from the dosage form, the dissolution or solubilization of the drug under physiological conditions, and the permeability across the gastrointestinal tract. Dissolution testing is an essential part of designing more effective solid dosage forms in pharmaceutical industry. Moreover, dissolution testing contributes to the selection of appropriate formulation excipients for improving the dosage form efficiency. This study aims to analyze in-vitro drug dissolution testing in solid dosage forms since 2010 in order to present a comprehensive outlook of recent trends. In doing that the previous studies in the literature are summarized in the form of a table to demonstrate the apparatuses used for dissolution testing, the media in which the solid dosage form is dissolved, the method preferred for analysis from dissolution media, the conditions of analyses and the results obtained.

Cancer is the primary leading cause of mortality in the world. The key of a successful cancer treatment depends on many important parameters, such as the application route, anticancer compound, and dosage form. Among the administration routes, oral application is the most widely used application method. However, oral administration of many molecules as conventional dosage forms is limited due to a major problem-low bioavailability. Nanoscale drug delivery systems can ensure oral administration and improve the oral bioavailability of the drugs. Determination of the chemotherapeutically active molecules from the developed nanoscale systems has an important role in the effectiveness of the nanoparticles. Chromatographic techniques, especially liquid chromatography, are very suitable and accurate ways to determine the content of a pharmaceutical ingredient and its stability in both in vitro and in vivo systems. This chapter describes the importance of lipid- and polymer-based nanoscale drug delivery technologies of the anticancer molecules and summarizes the effect and type of the nanostructures, characterization parameters, analysis parameters, such as column types and mobile phase compositions, and validation parameters. © 2017 Elsevier Inc. All rights reserved.

In the present study, new isocratic stability-indicating reverse phase chromatographic methods were developed using HPLC and UPLC systems for the determination of entacapone (ENT) in its pharmaceutical dosage forms. Ultra performance liquid chromatography (UPLC) using small sub-2 μm particles and high-performance liquid chromatography (HPLC) were compared for separation and determination of the ENT using Acquity HSS C18 (50 × 2.1 mm, 1.8 µm) and Xbridge C18 (150 × 4.6 mm, 5.0 µm) columns by UPLC and HPLC, respectively. When using UPLC, the run time could be reduced five fold and actually the solvent consumption decreased 10 times. The proposed UPLC method would decrease the consumption of organic solvents and reagents. The present methods were validated according to ICH guideline. All analytical procedures including sample preparation, flow rate, run time of the analytical systems were at low levels. Forced degradation studies were also performed for both compounds in bulk drug samples to demonstrate the specificity and stability-indicating comparative advantage of both methods.

Fulvestrant is used for the treatment of hormone receptor-positive metastatic breast cancer in postmenopausal women with disease progression following anti-estrogen therapy. Several reversed-phase columns with variable silica materials, diameters, lengths, etc., were tested for the optimization study. A good chromatographic separation was achieved using a Waters X-Terra RP(18) column (250 × 4.6 mm i.d. × 5 µm) and a mobile phase, consisting of a mixture of acetonitrile-water (65:35; v/v) containing phosphoric acid (0.1%). The separation was carried out 40 °C with detection at 215 nm.The calibration curves were linear over the concentration range between 1.0-300 and 1.0-200 µg/mL for standard solutions and biological media, respectively. The proposed method is accurate and reproducible. Forced degradation studies were also realized. This fully validated method allows the direct determination of fulvestrant in dosage form and biological samples. The average recovery of the added fulvestrant amount in the samples was between 98.22 and 104.03%. The proposed method was also applied for the determination of fulvestrant from the polymeric-based nanoparticle systems. No interference from using polymers and other excipients was observed in in vitro drug release studies. Therefore an incorporation efficiency of fulvestrant-loaded nanoparticle could be determined accurately and specifically.

Multiwalled carbon nanotube modified edge plane pyrolytic graphite electrode (MWCNT/EPPGE) was developed and implemented for the determination of antiretroviral drug Abacavir using differential pulse adsorptive stripping voltammetry (DP AdSV). Cyclic voltammogram showed two oxidation peaks located at +0.91 V and +1.10 V on (MWCNT/EPPGE). Dependency of peak potential and peak current on pH was investigated as details. The oxidation potentials affected by the pH indicating protons are involved in the electrochemical oxidation of Abacavir. Mass transport to the electrode surface was found as a combination of diffusion and adsorption which was concluded by studying the potential scan rate dependency of both peak currents. The oxidation mechanism was proposed using the obtained data and discussed. A large enhancement in both of the peak currents was observed with applying an accumulation step presenting the effect of adsorption. Peak currents showed a linear relation upon the Abacavir concentration within a range of 1 × 10−7–2 × 10−5 M with (r = 0.999) for both peak responses. The method was fully validated related with selectivity, sensitivity, precision and accuracy studies. Abacavir was also determined with the proposed method in its pharmaceutical dosage forms and human serum samples. No interferences from the excipients of the dosage form or endogenous substances from biological material were found.

In this study, direct and sensitive determination of famotidine based on its electrochemical oxidation was investigated in spiked human urine and tablet dosage forms. The electrochemical measurements were carried out in various buffer solutions in the pH range of 0.88 to 12.08 at ultra trace graphite electrode (UTGE) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The best results were obtained for the quantitative determination of famotidine by DPV technique in 0.5 mol L-1 H2SO4 solution (pH=0.30). In this strong acid medium, one irreversible anodic peak was observed. The effect of pH and scan rate on the peak current and peak potential were investigated. The diffusion-controlled nature of the peak was established. For optimum conditions described in the experimental section, a linear calibration curve for DPV analysis was constructed in the famotidine concentration range 2 x 10-6 - 9 x 10-5 mol L-1. Limit of detection (LOD) and limit of quantification (LOQ) were 3.73 x 10-7 and 1.24 x 10-6 mol L-1 at UTGE respectively. Repeatability, precision and accuracy of the developed technique were checked by recovery studies in spiked urine and tablet dosage forms.

The findings of this study revealed that hydrothermal carbonization (HTC) of filter parts of smoked cigarette butts generates carbonaceous materials that have porosity and high surface area (1012 m(2) g(-1)). This method is relatively eco-friendly because it performed in closed system and under mild conditions. In this study, porous carbon obtained from HTC of smoked cigarette filters was applied in an electroanalytical drug analysis. The surface morphology and chemical structure of the as-prepared materials were illuminated using with different techniques. The voltammetric behavior of antihypertensive drug trandolapril (TRD) was investigated on glassy carbon electrode (GCE) that modified by cigarette filter derived char/Nitrogen doped carbon spheres (c-char/NCS). The electrooxidation of TRD was demonstrated a diffusion-controlled fashion at pH 3.0 phosphate buffer (PB) solution. The calibration curve was linear between 8 x 10(-8) and 8 x 10(-5) M. The detection limit (LOD) was obtained as 1.09 x 10(-10) M in pH 3.0 PB solution and 2.57 x 10(-8) M in human serum samples by DPV. We try to show that the novel electrochemical sensor was easily applied for the determination of TRD using various carbon structures produced from urea and filter parts of cigarette butts. Scientific Research Projects Coordination Unit (BAP) of Ankara University, TurkeyAnkara University [18B0430007]; Higher Education Council of Turkey (YOK)Ministry of National Education - Turkey The authors offer their gratitude to Scientific Research Projects Coordination Unit (BAP) of Ankara University, Turkey for provide financial support within the Project 18B0430007. Higher Education Council of Turkey (YOK) was greatly appreciated for providing scholarship to Selva Bilge. The authors are also grateful to Prof. Dr. Zeki Aktas for BET analysis. In addition, the authors thank the pharmaceutical company ABBOTT for the materials. WOS:000475314800090 2-s2.0-85066404395

A sensitive, selective and accurate ultra performance liquid chromatographic method has been developed and validated for the simultaneous determination of bisoprolol fumarate and hydrochlorothiazide in their combined dosage forms and as well as in spiked human urine samples. The separation was achieved on an Acquity UPLC BEH C18 1.7 μm (2.1 × 50 mm) column, at 40 °C with mobile phase consisting of acetonitrile:phosphate buffer (20 mM) at pH 3.0 with a gradient elution at 225 nm. Bisoprolol fumarate and hydrochlorothiazide were well separated in

To support real biological sample application, a simple, selective and rapid LC–MS method has been developed and validated for the sensitive determination of metoclopramide in rabbit blood, ex vivo permeation studies and pharmaceutical dosage form. LC–MS analysis was performed isocratically on a Zorbax SB-C18 column with a mobile phase consisting of methanol:ammonium acetate buffer (pH 3.0) 75:25 (v/v) at a flow rate of 0.70 mL min−1. The outlet of the column was connected to a single quadrupole mass spectrometer with positive mass spectrometric detection. Ions were detected in the positive multiple reaction monitoring mode. The assay was linear over the concentration range of 1.25–200 pg μL−1 with a limit of detection of 0.077 pg μL−1 for standard solutions and 2.5–200 pg μL−1 with a limit of detection of 0.42 pg μL−1 for serum samples. The method is applicable, covering a variety of pharmaceutical and biological studies. Metoclopramide was extracted from rabbit blood by liquid–liquid extraction using ether as the extraction solvent. The reproducibility of the method was found to be between 0.96 and 1.98 % (RSD) values. The proposed method has been extensively validated for the determination of metoclopramide in all working media. The sample preparations, flow rate and run time of the analytical systems are not time consuming. Moreover, for the stability of metoclopramide, the effect of temperature, UV light, H2O2, HCl and NaOH were also investigated.

Liquid chromatography (LC) is a separation technique used in many different areas to aid the identification and quantification of substances in various matrices. LC techniques with various detection modes have been widely used for the sensitive and selective determination of trace amounts of pharmaceutical active compounds in biological samples and their dosage forms. A completely new system design with advanced technology has been developed, called ultra high performance liquid chromatography, which has evolved from high performance liquid chromatography. The application of LC methods to drug analysis introduces a powerful tool for therapeutic drug monitoring as well as for clinical research. The advantages of short turnaround time, method reliability, method sensitivity, and drug specificity justify the use of LC techniques for various groups of the drug active compounds. This review describes some of the principles of ultra high performance liquid chromatography and high performance liquid chromatography, validation of these methods, system suitability tests for the methods, and application of methods to pharmaceutical analysis in the last 3 years.

A RP-LC method is presented, which is sensitive and selective for the simultaneous determination of enalapril-lercanidipine and enalapril-nitrendipine binary mixtures in their pharmaceutical dosage forms. The analyte peaks were detected using the LC method with the mobile phase ratio of methanol: water (70:30 v/v, pH 3.0) and a 1.0 mL min-1 flow rate. The detection wavelength was selected at 210 nm using photo diode array detector and column temperature was optimized to 30 C. Linearity was obtained at different concentration ranges for all working pharmaceutically active compounds between 0.5 and 25 ?g mL-1. The proposed methods were extensively validated according to USP 27 requirements and ICH guidelines. The methods were applied to the analysis of pharmaceutical dosage forms containing binary mixtures of enalapril-lercanidipine and enalapril-nitrendipine. Moreover, the proposed methods were applied for the degradation studies of the selected compounds. Degradation studies were conducted using stress conditions such as UV light, acidic and alkaline hydrolysis, oxidation and heat in oven, to evaluate the ability of the separation of the response of standard compounds from their degradation products. © 2013 Springer-Verlag Berlin Heidelberg.

Valganciclovir hydrochloride (VAL) is an antiviral drug active compound which is used for the treatment of the cytomegalovirus infections. The voltammetric oxidation of VAL was investigated at multi-walled carbon nanotubes modified glassy carbon electrode using cyclic and differential pulse voltammetry over a wide pH range. The results revealed that the oxidation of VAL is an irreversible pH-dependent process in an adsorption-controlled mechanism. The results show that the oxidation signal was remarkably enhanced to provide down to the ultra trace levels. Operational parameters have been optimized. The calibration curve was linear in the concentration range of 7.50 × 10 −9 –1.00 × 10 −6 M with the detection limit of 1.52 × 10 −9 M. The reproducibility of the peak current was found 2.07% ( n = 5) relative standard deviation (RSD) value in pH 4.0 Britton-Robinson (BR) buffer for the modified electrode. The modified electrode showed good stability and reproducibility, and also it was successfully applied to the sensitive and selective determination of VAL in its dosage forms.

The equation that express the combined effect of the organic modifier content and mobile phase pH has been used to predict the chromatographic behavior of flurbiprofen, ibuprofen, diclofenic acid, ketoprofen, fenoprofen, naproxen, bezafibric acid and clofibric acid. Correlations between the retention factors of the solutes and pH of the mobile phase were determined from a set of 40 chromatograms for each compound at four different levels of acetonitrile composition (40, 45, 50 and 55 %, v/v), and at ten pH values in each acetonitrile–water mixtures. In this way, a complete description of the retention behavior of each solute in the space defined by the pH and organic modifier percentages variables was obtained. The optimized chromatographic condition was applied to quantitative determination of flurbiprofen, ibuprofen, and diclofenic acid in pharmaceutical dosage forms.

The aim of the present study was to develop a fast, sensitive and reliable method for rapid screening of cephalosporin injectable dosage forms namely ceftazidime and ceftizoxime to the detection of counterfeit and substandard drugs that might be illegally commercialized. Ceftazidime, ceftizoxime and cefixime (IS) were separated in a X-Terra RP-18 column (250 × 4.60 mm ID × 5 μ) and DAD detector set at 290 and 260 nm. The mobile phase consisted of a mixture of methanol:water 20:80 (v/v) at a flow rate of 1.0 mL min−1. Additionally, in order to find the optimum pH value of separation the pK a values of studied compounds were determined by using two different methodologies. Aqueous pK a values of studied compounds have been determined by UV-spectrophotometry and liquid chromatography were used for the determination and direct characterization of the dissociation constants by using the dependence of the capacity factor on the pH of the mobile phase in 20% (v/v) methanol–water binary mixture in which separation was performed. The pH of the mobile phase was adjusted with 25 mM H3PO4 to 3.2. The method was shown to be linear, sensible, accurate, and reproducible over the range of analysis and it can be used to pharmaceutical formulations containing a single active ingredient within a short analysis time.

Ezetimibe is the first of a new class of drugs that selectively inhibits cholesterol absorption in the small intestine and reduces plasma LDL cholesterol. In this study, electrochemical oxidation of ezetimibe was investigated on carbon based electrodes and a single and irreversible peak at both electrodes was observed. A linear response was detected between 2 × 10−6 and 8 × 10−5 M with glassy carbon electrode and between 2 × 10−6 and 2 × 10−4 M with a boron-doped diamond electrode in 0.1 M H2SO4 supporting electrolyte. The proposed methods were successfully applied for the determination of ezetimibe from pharmaceutical dosage forms and human serum samples.

The interaction of fulvestrant with double-stranded DNA (dsDNA) was studied by means of differential pulse voltammetry (DPV) at dsDNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals was used as an indicator for the interaction mechanism and sensitive determination of fulvestrant in pH 4.80 acetate buffer (30% ethanol). A linear dependence of the guanine oxidation signals was observed within the range of 1.00–20.00 μg/mL fulvestrant, with a detection limit of 0.41 μg/mL. The determination method was validated according to the standard validation procedure. The proposed method was applied to fulvestrant pharmaceutical dosage form.

The electrochemical behavior of L-dopa and benserazide at a solid electrode has been investigated using different voltammetric techniques. The anodic voltammetric characteristics of the selected compounds have been studied in aqueous media as a function of pH by cyclic, differential pulse and square wave voltammetric techniques. First derivative of the ratio voltammetric methods for determination of these compounds in their dosage forms in the presence of each other has been described. This technique depends on the measuring of the first derivative of ratio voltammograms of each concentration as a function of the increased concentrations. DP and SW voltammetric methods depend on the measuring of first derivative of the ratio voltammetry by measurements of the selected potentials corresponding to either maximums or minimums for both drugs. The linear response was within the range of 1 × 10–5–8 × 10–5 and 1 × 10–5 – 2 × 10–4 M for L-dopa and benserazide, respectively. The validity of the proposed methods was successfully assessed for analyses of both drugs in laboratory-prepared mixtures and in commercial tablet formulations. The proposed methods have successfully applied to the simultaneous determination of these compounds in the presence of each other.

In the present study, the combined effect of mobile phase polarity and pH on retention behavior of some ARA-IIs (irbesartan, losartan, valsartan and telmisartan) is investigated. The linear relationships established between retention factors of the species and the polarity parameter of the mobile phase has proved to predict accurately retention in LC as a function of the acetonitrile content (50%, 55%, 60%, v/v). The suggested model uses the pH value in the acetonitrile–water mixture as mobile phase instead of pH value in water and takes into account the effect of activity coefficients. Moreover, correlation between retention and the mobile phase pH can be established allowing prediction of the retention behavior as a function of the mobile phase pH. The model can be used to estimate the p K a in an acetonitrile percentage between 50% and 60%, at 30 °C. The developed method was successfully applied to both the simultaneous separation of these drug-active compounds and individual determination in their commercial pharmaceutical dosage forms.

The anodic voltammetric behavior and electroanalytical determination of rosiglitazone was studied using cyclic, linear sweep, differential pulse and square wave voltammetric techniques on glassy carbon electrode. The oxidation of rosiglitazone was irreversible and exhibited diffusion controlled process depending on pH. Different parameters were tested to optimize the conditions for the determination of the oxidation mechanism of rosiglitazone. The dependence of current intensities and potentials on pH, concentration, scan rate, nature of the buffer was also investigated. According to the linear relationship between the peak current and the concentration, differential pulse and square wave voltammetric methods for rosiglitazone assay in pharmaceutical dosage forms and biological fluids were developed. A linear response was obtained within the range of 1x10-6M - 6x10-5M in 0.1 M H2SO4 and acetate buffer at pH 5.70 for both voltammetric methods in human serum samples. The practical analytical value of the method is demonstrated by quantitative determination of rosiglitazon in pharmaceutical formulation and human serum, without the need for separation or complex sample preparation, since there was no interference from the excipients and endogenous substances. The methods were fully validated and successfully applied to the high throughput determination of the drug in tablets and human serum with good recoveries.

Ziprasidone is a psychotropic agent used for the treatment of schizophrenia. Its oxidation was investigated electrochemically at boron-doped diamond and glassy carbon electrodes using cyclic, differential pulse, and square wave voltammetry. The dependence of the peak current and peak potentials on pH, concentration, nature of the buffer, and scan rate were examined. The process was diffusion and adsorption controlled for boron-doped diamond and glassy carbon electrodes, respectively. The possible mechanism of oxidation was discussed with some model compounds that have indole and piperazine oxidations. A linear response was obtained between 8 × 10-7 and 8 × 10-5 M for the first peak in acetate buffer (pH 5.5) and between 2 × 10-6 and 2 × 10-4 M for the second peak in 0.1 M H2SO4 with boron-doped diamond electrode for differential pulse and square wave voltammetric techniques. The reproducibility and accuracy of the proposed methods were found between 0.31 and 1.20, 99.27 and 100.22, respectively. The recovery studies were also achieved to check selectivity and accuracy of the methods. The proposed methods were applied for the determination of ziprasidone from pharmaceutical dosage forms and human serum samples without any time-consuming extraction, separation, evaporation or adsorption steps prior to drug assay except precipitation of the proteins using acetonitrile. The results were statistically compared with those obtained through an established LC-UV technique, no significant differences were been found between the voltammetric and LC methods. © 2010 Elsevier B.V. All rights reserved.

A review of the applications, principles, advantages of stripping voltammetric techniques, namely anodic, cath- odic, abrasive, adsorptive stripping voltammetry and potentiometric stripping analysis is presented. Stripping voltammet- ric methods in pharmaceutical analysis are discussed and the generally applicable procedure is given. The use and advan- tages and disadvantages of these techniques at different electrodes are discussed. The analytical applications of stripping techniques to pharmaceutically active compounds are also discussed. Various selected determination studies on drugs by stripping techniques from pharmaceutical dosage forms and biological samples are reviewed.

The anodic behavior and determination of pefloxacin on boron-doped diamond and glassy carbon electrodes were investigated using cyclic, linear sweep, differential pulse and square wave voltammetric techniques. In cyclic voltammetry, pefloxacin shows one main irreversible oxidation peak and additional one irreversible ill-defined wave depending on pH values for both electrodes. The results indicate that the process of pefloxacin is irreversible and diffusion controlled on boron-doped diamond electrode and irreversible but adsorption controlled on glassy carbon electrode. The peak current is found to be linear over the range of concentration 2 × 10 −6 to 2 × 10 −4 M in 0.5 M H 2 SO 4 at about +1.20 V (versus Ag/AgCl) for differential pulse and square wave voltammetric technique using boron-doped diamond electrode. The repeatability, reproducibility, precision and accuracy of the methods in all media were investigated. Selectivity, precision and accuracy of the developed methods were also checked by recovery studies. The procedures were successfully applied to the determination of the drug in pharmaceutical dosage forms and humans serum samples with good recovery results. No electroactive interferences from the excipients and endogenous substances were found in the pharmaceutical dosage forms and biological samples, respectively.

The electrochemical behavior of atorvastatin calcium at glassy carbon and boron-doped diamond electrodes has been studied using voltammetric techniques. The possible mechanism of oxidation was discussed with model compounds. The dependence of the peak current and potentials on pH, concentration, scan rate and nature of the buffer were investigated for both electrodes. The oxidation of atorvastatin was irreversible and exhibited a diffusion-controlled fashion on the diamond electrode. A linear response was obtained within the range of 9.65 x 10(-7) - 3.86 x 10(-5) M in 0.1 M H(2)SO(4) solution for both electrodes. The detection limits of a standard solution are estimated to be 2.11 x 10(-7) M with differential pulse voltammetry (DPV) and 2.05 x 10(-7)M with square wave voltammetry (SWV) for glassy carbon electrode, and 2.27 x 10(-7) M with DPV and 1.31 x 10(-7)M with SWV for diamond electrodes in 0.1 M H(2)SO(4) solution. The repeatability of the methods was found good for both electrodes. The methods were fully validated and successfully applied to the high-throughput determination of the drug in tablets, human serum and human urine with good recoveries.

This paper describes the validation of an isocratic high-performance liquid chromatographic method for the assay of valganciclovir in raw materials, tablets and human serum samples. Valganciclovir and fluvastatin (internal standard) were well separated using a reversed phase column and a mobile phase consisting of a mixture of acetonitrile:methanol:KH2PO4 (0.02 M) (40:20:40; v/v/v) (at pH 5.0). The mobile phase was pumped at 1.0 mL min−1 flow rate and valganciclovir was detected by diode-array detection at 255 nm. The retention times for valganciclovir and fluvastatin were 3.41 and 5.60 min, respectively. A linear response (r > 0.999) was observed in the range of 10–30,000 ng mL−1 in mobile phase and serum. The limit of detection and limit of quantification were found as 2.95 and 9.82 ng mL−1 in mobile phase and 1.73 and 5.77 ng mL−1 in human serum samples, respectively. Validation parameters as precision, accuracy, selectivity, reproducibility and system suitability tests were also determined. The method can be used for valganciclovir assay of tablets and human serum samples as the method separates valganciclovir from tablet excipients and endogenous substances.

Many pharmaceutical compounds have electroactive groups and are readily measurable and detectable by liquid chromatography with electrochemical detection (LC–EC). LC–EC techniques have many advantages as measurement systems and new materials have been developed for working electrodes. Use of modern electroanalytical techniques for detection in LC of pharmaceutical compounds is discussed in this review. EC detection in LC often results in improved selectivity and detection limits for electroactive pharmaceutical compounds. Selected literature on the determination of pharmaceutical compounds in their dosage forms and in biological samples are reported.

A simple, accurate, precise and fully automated method for the simultaneous determination of abacavir, lamivudine and zidovudine in pharmaceutical tablets, human serum samples and drug dissolution studies has been developed. Separation was performed on a 5 μm Zorbax® C18 column (150 × 4.6 mm ID) with methanol:water:phosphate buffer at pH 5.65 (80:10:10; v/v/v) isocratic elution in less than 7 min with a flow rate of 0.6 mL min−1.Good sensitivity for all analytes was observed with UV detection at 275 nm. The method allowed quantitation over the 500–3,000 ng mL−1 range for abacavir and 500–5,000 ng mL−1 range for lamivudine and zidovudine. The method has been applied, without any interference from excipients or endogenous substances, for the simultaneous determination of these three compounds in tablets. Human serum and drug dissolution studies.

Etoposide is a topoisomerase II enzyme inhibitor type chemotherapeutic agent which is widely used in the therapy of various cancers. Its short half-life and toxicity to normal tissues are the major drawbacks in its clinical applications. Polymeric nanoparticulate drug delivery systems are rational carriers to deliver etoposide with higher efficiency and fewer side effects. In addition tubular shaped drug carriers are found to show a great potential for drug delivery on the basis of promising results regarding particle shape and cellular uptake. In this study, etoposide loaded polymeric tubular nanocarriers have been developed by template wetting method using porous anodic aluminum oxide membranes as templates. The developed poly(methyl methacrylate) nanocarriers were evaluated for structural analysis, in vitro drug release studies and drug release kinetics. Accurate and reliable determination of the drug release from newly developed nanocarriers, is of great importance. For this reason a selective and sensitive reversed phase liquid chromatography method was developed and fully validated from the point of system suitability, specificity, linearity and range, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy and robustness for the reliable determination of etoposide. Stability indicating capability was shown with forced degradation studies and the chromatographic conditions were optimized on ACE 5C18 (150 mm × 4.6mm I.D., 5 μm) analytical column. Related to the calibration results ETP was found linear in the range between 0.2 from 100 μg mL(-1) with the LOD as 0.015 μg.mL(-1). The resultant conditions were applied for the selective and sensitive determination of etoposide from its commercial dosage form with the high accuracy values (99.82-100.65%). The method was successfully detected assay of etoposide release from newly developed polymeric tubular nanocarriers, which was found as 72.2% at the end of 24h.

Simple, rapid, sensitive, and reproducible methods were developed for the assay of paroxetine in tablets. The electrooxidative behavior and determination of paroxetine on boron-doped diamond and edge plane graphite electrodes were investigated as details using cyclic, differential pulse, and square wave voltammetric methods. The oxidation process was irreversible and exhibited mixed diffusion-adsorption controlled process depending on pH. The dependence of the peak current and peak potentials on pH, nature of the buffer, and scan rate studies were examined as details. The linear responses have been obtained in the range from 7.0 × 10?7 M to 3.5 × 10?6 M with 6.95 × 10?9 M detection limit for the boron-doped diamond electrode and from 1.0 × 10?8 M to 5.0 × 10?6 M with 1.03 × 10?9 M detection limit for the edge plane graphite electrode. The possible electrooxidation mechanism of paroxetine was investigated by means of model compounds of tamsulosin and mebeverine. It can be suggested that alkoxybenzene moiety may be the responsible group for the oxidation of paroxetine (PRX). The developed methods have been successfully applied for the determination of paroxetine in pharmaceutical dosage form. © 2015, Springer-Verlag Berlin Heidelberg.

Ascorbic acid is the most common electroactive biological compound found in some plant species (e.g., Citrus species, Rosa species). The electrochemical oxidation of ascorbic acid was investigated by cyclic, linear sweep, differential pulse (DPV), and square wave (SWV) voltammetry. For analytical purposes, a very well-resolved diffusion-controlled voltammetric peak was obtained in acetate buffer at pH 3.50 for DPV and SWV. The linear response was obtained in the range of 3.52–176.1 μg/mL with a detection limit of 0.88 μg/mL for DPV and 0.52 µg/mL for SWV. Based on this study, simple, rapid, selective, and sensitive voltammetric methods were developed for the determination of ascorbic acid in pharmaceutical dosage forms and Rosa species (R. dumalis ssp. boissieri var. boissieri, R. canina, R. pulverulenta, R. heckeliana ssp. vanheurckiana, and R. montana subsp. woronowii). The results obtained are compared with the HPLC data. The developed methods enable the extracts to be analyzed without the necessity of any time-consuming separation.

Carvedilol is used in the management of hypertension and angina pectoris and as an adjunct to standard therapy in symptomatic heart failure. The electrochemical oxidation of carvedilol was investigated using cyclic, linear sweep voltammetry at a glassy carbon electrode. In cyclic voltammetry, in all values of pH, the compound shows two irreversible oxidation peaks. These two peaks are related to the different electroactive part of the molecule. First and second peak currents were found as diffusion and adsorption controlled, respectively. Using second oxidation step, two voltammetric methods were described for the determination of carvedilol by differential pulse adsorptive stripping voltammetry (AdSDPV) and square-wave adsorptive stripping voltammetry (AdSSWV) at a glassy carbon electrode. Accumulation of carvedilol was found to be optimized in 0.2 M H2SO4 solution following 275 second accumulation time at open circuit condition. Under optimized conditions, the current showed a linear dependence with concentration in the range between 2×10−7 M and 2×10−5 M in supporting electrolyte and in the range between 2×10−7 M and 1×10−5 M in spiked human serum samples for both methods. These methods were successfully applied for the analysis of carvedilol pharmaceutical dosage forms and spiked human serum samples. The repeatability and reproducibility of the methods for all media were determined. Precision and accuracy were also found. No electroactive interferences from the tablet excipients and endogenous substances from biological material were found.

The voltammetric behavior of cefixime was studied using cyclic, linear sweep, differential pulse and square wave voltammetric techniques. The oxidation of cefixime was irreversible and exhibited diffusion controlled process depending on pH. The oxidation mechanism was proposed and discussed. Different parameters were tested to optimize the conditions for the determination of cefixime. The dependence of current intensities and potentials on pH, concentration, scan rate, nature of the buffer was investigated. According to the linear relationship between the peak current and the concentration, differential pulse (DPV) and square wave (SWV) voltammetric methods for cefixime assay in pharmaceutical dosage forms and biological fluids were developed. For the determination of cefixime were proposed in acetate buffer at pH 4.5, which allows quantitation over the 6 × 10−6–2 × 10−4 M range in supporting electrolyte and spiked serum sample; 8 × 10−6–2 × 10−4 M range in urine sample; 6 × 10−6–1 × 10−4 M range in breast milk samples for both techniques. The repeatability, reproducibility, precision and accuracy of the methods in all media were investigated. No electroactive interferences from the excipients and endogenous substances were found in the pharmaceutical dosage forms and in the biological samples, respectively.

Lamivudine (LAM) is a synthetic nucleoside analogue with activity against human immunodeficiency virus-type 1 (HIV-1) and Hepatitis B virus (HBV). The aim of this study was to determine LAM levels in serum and pharmaceutical formulations, by means of electrochemical methods using hanging mercury drop electrode (HMDE). On this electrode, LAM undergoes irreversible reduction at the peak potential near Ep−1.26 V (vs. Ag/AgCl/3 M KCl). Reduction LAM signals were measured by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and square-wave voltammetry (OSW). DPV and OSW techniques for the determination of LAM in acetate buffer at pH 4.5, which allows quantitation over the 4×10−6 to 1×10−4 M range in supporting electrolyte for both methods, were proposed. The linear response was obtained in acetate buffer in the ranges of 2×10−6 to 2×10−4 M for spiked serum samples at pH 4.5 for both techniques. The repeatability and reproducibility of the methods for all media were determined. The standard addition method was used in serum. Precision and accuracy were also checked in all media. No electroactive interferences from the endogenous substances were found in serum. With respect to side effects of high doses and short half-life of LAM, a fast and simple detection method is described in this study.

The electrochemical reduction behavior of mefloquine HCl (MEF), the antimalarial drug, was studied in aqueous alcoholic media at a hanging mercury drop electrode. Cyclic voltammetric studies showed one well-defined reduction peak and one ill-defined reduction wave between pH 1.5 and 12.03. The reduction was found as irreversible or quasireversible depending on pH and exhibited diffusion controlled process. The mechanism of reduction process was discussed. A systematic study of the experimental parameters that affect the differential pulse and square wave response was carried out and the optimized experimental conditions were obtained. The calibration plots were derived for the determination of MEF in pharmaceutical dosage forms and biological samples. DPV and SWV techniques for the determination of MEF in Britton–Robinson buffer at pH 11.10, which allows quantitation over the 6×10−6 to 8×10−5 M range in the supporting electrolyte, were proposed. The linear response was obtained in samples in the ranges of 6×10−6 to 6×10−5 M for both techniques. These methods are fully validated. The standard addition method was used in the biological media. No electroactive interferences from the excipients and endogenous substances were found in tablets and biological fluids.

Flupenthixol hydrochloride (FLP) has an antipsychotic activity against depression and is irreversible oxidizable at the glassy carbon electrode in various buffer systems and at different pH values. The mechanism of the oxidation process was discussed. According to the linear relation between the peak current and FLP concentration, differential pulse and square wave voltammetric methods for its determination in pharmaceutical dosage forms and spiked human serum samples were developed. For analytical purposes, a very well resolved diffusion controlled voltammetric peak was obtained in Britton‐Robinson buffer at pH 7.02 (20% methanol) at 0.75 and 0.79 V for differential pulse and square wave voltammetric techniques, respectively. The linear response was obtained in the ranges of 8 × 10−7 to 1 × 10−4 M with a detection limit of 1.17 × 10−7 M for differential pulse and 1 × 10−6 to 1 × 10−4 M with a detection limit of 2.86 × 10−7 M for square wave voltammetric techniques. The repeatability and reproduc...

This work describes a new, fully validated, simple, rapid, selective, and sensitive HPLC method with UV detection for the direct determination of abacavir in pharmaceutical dosage forms, raw materials, spiked human serum, and drug dissolution studies without any time‐consuming extraction or evaporation steps prior to drug assay. The mobile phase employed was methanol∶acetonitrile: 0.015 M KH2PO4 (36∶2.6∶61.4 v/v/v) adjusted to pH 6.9 with 5 N NaOH. The samples of 20 µL were injected onto a Waters Spherisorb ODSI (250 × 4.6 mm, 5 µm particle size) column. Ketoprofen was used as internal standard. The flow rate was 1.0 mL min−1. The retention times were 5.49 min for abacavir and 9.15 min for ketoprofen in mobile phase, 5.46 min for abacavir and 9.24 min for ketoprofen in serum samples. The samples were detected at 284 nm. The assay was linear in the concentration range 0.010–20 µgmL−1 (r = 0.999) with a slope of 1.35 × 10−3; intercept of 0.0841 and the limit of detection was 0.00093 µg mL−1 in mobi...

Abacavir has an antiretroviral activity against HIV and is oxidizable at the glassy carbon electrode. Cyclic voltammetry studies showed one well-defined oxidation wave or splitted two waves depending on pH. The oxidation was irreversible and exhibited diffusion controlled process depending on pH. The mechanism of the oxidation process was discussed. According to the linear relation between the peak current and the concentration, differential pulse voltammetric (DPV) and square wave voltammetric (SWV) methods for its quantitative determination in pharmaceutical dosage forms and biological fluids were developed. These two voltammetric techniques for the determination of abacavir in Britton–Robinson buffer at pH 2.0, which allows quantitation over the 8×10 −7 to 2×10 −4 M range in supporting electrolyte for both methods were proposed. The linear response was obtained in Britton–Robinson buffer in the ranges of 1×10 −5 to 1×10 −4 M for spiked urine sample at pH 2.0 and 2×10 −5 to 2×10 −4 M for spiked serum samples at pH 3.0 for both techniques. The repeatability and reproducibility of the methods for all media (such as supporting electrolyte, serum and urine samples) were determined. Precision and accuracy were also checked in all media. The standard addition method was used in biological media. No electroactive interferences from the endogenous substances were found in the biological fluids.

A high performance liquid chromatographic (HPLC) method is described for the determination of rofecoxib (RFC) in bulk drug, tablets, and human plasma samples. The methods are linear over the concentration ranges 0.005–30.0 and 0.010–10 µg mL−1 in mobile phase and human plasma, respectively. Chromatography was carried out on a reversed phase Spherisorb ODSI column using a mixture of acetonitrile:methanol: 0.067 M KH2PO4 (27:20:53, v/v/v) adjusted to pH 6.95 with 3 M NaOH. Detection was realized at 244 nm using a DAD detector. The retention time observed for RFC and etodolac (internal standard) at about 7.5 and 10.7 min, respectively. The proposed RP‐HPLC method was validated for precision, accuracy, ruggedness, and recovery. The limit of detection was found to be 0.00143 and 0.00301 µg mL−1 in mobile phase and human plasma samples, respectively. The proposed method allows a number of cost and time saving benefits. The described method can be readily applied for the analysis of tablets, drug dissol...

The electrooxidative behavior and determination of Tamsulosin HCl (TAM), one of the alpha(1)-adrenoceptor antagonist, on a glassy carbon disc electrode were investigated for the first time by using cyclic, linear sweep, differential pulse (DPV) and square wave voltammetry (SWV). TAM showed an irreversible oxidation behavior at all pH values and buffers studied. From the electrochemical response, the main oxidation step was found to be related to the methoxy group on the phenyl ring. DPV and SWV were used to generate peak current versus concentration curves for TAM. A linear response was obtained in the range comprised between 2x10(-6) and 4x10(-4) M for both techniques with detection limit of 3.34x10(-7) M for DPV and 2.45x10(-7) M for SWV. The methods were proposed for the determination of TAM in dosage forms adopting both DPV and SWV modes. The methods were extended to the in vitro determination of TAM in spiked serum samples.

A simple, sensitive, reproducible, and validated RP‐HPLC method with UV detection is described for the determination of deflazacort in raw material, pharmaceuticals, human serum samples, and in‐vitro drug dissolution studies. The separation was achieved using a C18 (250 × 4.6 mm; 5 µm) column and a mobile phase comprising acetonitrile, methanol, and 0.067 M KH2PO4 in the ratio (27:20:53, v/v/v), adjusted to pH 6.5 with 3 M NaOH. The results of analysis were treated statistically and it has been validated and proven to be rugged. The limit of detection and limit of quantification were found as 2.05 ng mL−1 and 6.83 ng mL−1 in mobile phase and 4.06 ng mL−1 and 13.55 ng mL−1 in human serum samples, respectively. The method produced linear response in the concentration ranges 10–30,000 ng mL−1 in mobile phase and 25–30,000 ng mL−1 in serum samples. The intra‐ and inter‐day assay precision of the method was within 0.92% relative standard deviations in mobile phase and 1.48% relative standard deviation...

A specific, sensitive, simple, and rapid HPLC method has been developed for the determination of valacyclovir (VACL) in raw material, pharmaceutical dosage forms, and human serum, in order to carry out drug dissolution studies from tablets. The chromatographic separation was achieved with acetonitrile:methanol:0.067 M KH2PO4 (27:20:53, v/v/v) adjusted to pH 6.5 with 3 M NaOH as mobile phase, a Waters Spherisorb C18 column, and UV detection at 244 nm. Etodolac was used as an internal standard. Linearity range was 5–20,000 ng mL−1. Limit of detection obtained was 0.38 and 0.14 ng mL−1 in mobile phase and spiked human serum samples, respectively. The described method can be readily applied, without any interferences from the excipients, for the determination of the drug in tablets, human serum samples, and drug dissolution studies. #Presented at 11th International Pharmaceutical Technology Symposium, September 9–11, 2002, Istanbul, Turkey.

In the present study, a simple, sensitive, precise, and rapid HPLC method with UV detection for the analysis of lamivudine is developed and applied to the determination of anti HIV drug in commercial pharmaceutical dosage forms (tablets and oral solutions) and human serum. The gradient elution is performed with methanol:water (75 : 25, v/v) at a flow rate of 0.8 mLċmin−1, using a Spherisorb® C18 analytical column 150 × 4.6 mm, 5 µm. Deflazacort is used as internal standard. Absorbance is monitored at 265 nm. Total analysis time was ∼6 min. Data, with respect to precision and accuracy and limits of detection, are reported and discussed. The described method can be readily utilized for analysis of pharmaceutical products and pharmacokinetic studies as well.