Simultaneous Determination Of Lamivudine Research Articles

Simultaneous Spectrophotometric Determination of Lamivudine and Stavudine using π-Acceptors as Analytical Reagents

Two new sensitive and precise spectrophotometric methods have been proposed and developed for the simultaneous estimation of lamivudine and stavudine in pure mixture and in pharmaceutical binary dosage forms. A new concept of area under curve (AUC) is proposed for simultaneous estimation of two drugs by these methods. Method A involves the use of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as analytical reagent and the AUC between 390 nm and 690 nm for DDQ was used for determination. Method B involves the use of p-chloranilic acid: 2,5-dichloro-3,6-dihydroxy-1,4- benzoquinone (p-CA) as an analytical reagent and the AUC between 400 and 700 nm for p-chloranilic acid was used for deter-mination. The methods developed and construction of calibration curves using two analytical reagents viz., DDQ and p-chloranilic acid are described. Optical and analytical parameters for the individual and simultaneous determination of lamivudine and stavudine using AUC are tabulated. The methods have been validated and compared with HPLC methods in terms of standard deviation, t-test and F-test.

Thin-layer chromatographic monitoring of sonolytic degradation of surfactants in wastewaters

This paper describes the development and validation of high-performance thin-layer chromatography (HPTLC) method for the simultaneous determination of lamivudine (LAM), tenofovir disoproxil fumarate (TDF) and efavirenz (EFV). The separation was carried out on Merck HPTLC aluminum plates precoated with silica gel G60 F254 (20 × 10 cm) with 250-μm thickness using chloroform-methanol-toluene (9:1.2:0.3, v/v) as mobile phase. HPTLC separation of the three drugs followed by densitometric measurement was carried out in the absorbance mode at 260 nm. The drugs were resolved satisfactorily with RF values of 0.20 ± 0.02, 0.61 ± 0.01 and 0.73 ± 0.02 for LAM, TDF and EFV, respectively. The linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.9997, 0.9991 and 0.9990 for LAM, TDF and EFV, respectively, in the concentration range of 400–800 ng spot−1 for LAM and TDF and 800–1600 ng spot−1 for EFV. The limit of detection and quantitation were 180 and 300 ng spot−1, respec...

Continuous Wavelet Transforms for the Simultaneous Quantitative Analysis and Dissolution Testing of Lamivudine–Zidovudine Tablets

Dissolution testing has a very vital importance for a quality control test and prediction of the in vivo behavior of the oral dosage formulation. This requires the use of a powerful analytical method to get reliable, accurate and precise results for the dissolution experiments. In this context, new signal processing approaches, continuous wavelet transforms (CWTs) were improved for the simultaneous quantitative estimation and dissolution testing of lamivudine (LAM) and zidovudine (ZID) in a tablet dosage form. The CWT approaches are based on the application of the continuous wavelet functions to the absorption spectra-data vectors of LAM and ZID in the wavelet domain. After applying many wavelet functions, the families consisting of Mexican hat wavelet with the scaling factor a=256, Symlets wavelet with the scaling factor a=512 and the order of 5 and Daubechies wavelet at the scale factor a=450 and the order of 10 were found to be suitable for the quantitative determination of the mentioned drugs. These wavelet applications were named as mexh-CWT, sym5-CWT and db10-CWT methods. Calibration graphs for LAM and ZID in the working range of 2.0-50.0 µg/mL and 2.0-60.0 µg/mL were obtained measuring the mexh-CWT, sym5-CWT and db10-CWT amplitudes at the wavelength points corresponding to zero crossing points. The validity and applicability of the improved mexh-CWT, sym5-CWT and db10-CWT approaches was carried out by the analysis of the synthetic mixtures containing the analyzed drugs. Simultaneous determination of LAM and ZID in tablets was accomplished by the proposed CWT methods and their dissolution profiles were graphically explored.

Simultaneous determination of lamivudine, lopinavir, ritonavir, and zidovudine concentration in plasma of HIV‐infected patients by HPLC‐MS/MS

The nucleoside reverse transcriptase inhibitors lamivudine and zidovudine and the protease inhibitors lopinavir and ritonavir are currently used in anti-human immunodeficiency virus (HIV) therapy. Here, a high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) method, using a hybrid quadrupole time-of-flight mass analyzer, is reported for the simultaneous quantification of lamivudine, lopinavir, ritonavir, and zidovudine in plasma of HIV-infected patients. The volume of plasma sample was 600 μL. Plasma samples were extracted by solid-phase using 1 cc Oasis HLB Cartridge (divinylbenzene and N-vinylpyrrolidone) and evaporated in a water bath under nitrogen stream. The extracted samples were reconstituted with 100-μL methanol. Five microliters of the reconstituted samples were injected into a HPLC-MS/MS apparatus, and the analytes were eluted on a Vydac column (250 × 1.0 mm i.d.) filled with 3-μm C(18) particles. The mobile phase was delivered at 70 μL/min with a linear gradient elution, both acetonitrile and ultrapure water solvents contained 0.2% formic acid. The calibration curves were linear from 0.47 to 20 ng/mL. The absolute recovery ranged between 91 and 107%. The minimal concentration of lamivudine, lopinavir, ritonavir, and zidovudine detectable by HPLC-MS/MS is 0.47, 0.28, 0.30, and 0.66 ng/mL, respectively. The great advantage of the new HPLC-MS/MS method here reported is the possibility to achieve a very high specificity toward the selected anti-HIV drugs, despite the simple and rapid sample preparation. Moreover, this method is easily extendible to the analysis of co-administrated drugs.

Simultaneous determination of lamivudine, stavudine and nevirapine in human plasma by LC–MS/MS and its application to pharmacokinetic study in clinic

A new high-throughput LC-MS/MS method for the simultaneous determination of lamivudine (3TC), stavudine (d4T) and nevirapine (NVP) in human plasma is presented, with zidovudine as an internal standard. The analytes were extracted from plasma by protein precipitation and only 150 microL plasma was needed. Chromatographic separation was achieved on a Shiseido C(8) column (150 x 2.0 mm, 5 microm) with a total run time of 6 min. A tandem mass spectrometric detection was conducted using multiple reaction monitoring under positive ionization mode with an electrospray ionization interface. The method was developed and validated over the concentration range of 25-5000 ng/mL for 3TC and NVP and 20-4000 ng/mL for d4T. The method was validated in terms of intra- and inter-day precision (< or = 8.6%), accuracy (within +/- 8.4%), linearity and specificity. The method has been successfully applied to the pharmacokinetic study of a combination treatment of 300 mg lamivudine, 30 mg stavudine and 200 mg nevirapine in 22 healthy male volunteers under fasting conditions.

Simultaneous Separation and Determination of Lamivudine and Zidovudine in Pharmaceutical Formulations Using the HPTLC Method

A high-performance thin-layer chromatographic method (HPTLC) for the simultaneous determination of lamivudine and zidovudine in a binary mixture has been developed. The method developed was based on HPTLC separation of the two drugs followed by densitometric measurements of spots at 276 and 271 nm for lamivudine and zidovudine, respectively. Separation was carried out on Merck HPTLC silica-gel 60 F254 plates, using toluene/chloroform/methanol (1:6:3 v:v) as the mobile phase. Validation of the method was performed based on The International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidelines in terms of linearity, accuracy, precision, limit of detection, limit of quantification, and robustness. Second-order polynomial equations were obtained for the regression line in the ranges of 250–1400 and 250–1700 ng/spot for lamivudine and zidovudine respectively. Correlation coefficient (r) values were 0.9998 for both analytes. The method provides sufficient accuracy as indicated by recovery percentages given for lamivudine and zidovudine. For system precision study, the low coefficient of variation values (<2%) for both lamivudine and zidovudine ensured reproducible performance of the instrument. In the method precision study, coefficients of variation <2% were obtained, which showed that the proposed method provides acceptable intraday and interday variation. The detection and quantification limits and were 3.06 and 9.28 ng/spot for lamivudine and 3.34 and 10.13 ng/spot for zidovudine, respectively. Parameters such as mobile-phase composition, volume of mobile phase, time from spotting to development, and time from development to scanning were employed while testing for robustness of the method, and the standard deviation of peak areas was calculated for each parameter. The low coefficient of variation values indicated the robustness of the method. Statistical manipulation did not show any significant effect of one parameter over the others on the robustness of the method.

Simultaneous determination of lamivudine, stavudine and nevirapine in antiretroviral fixed dose combinations by high performance liquid chromatography

An accurate, sensitive and specific reversed phase high performance liquid chromatographic method (RP-HPLC) for the simultaneous quantitative determination of the nucleoside reverse transcriptase inhibitors lamivudine, stavudine with the non-nucleoside reverse transcriptase inhibitor nevirapine in pharmaceutical fixed dose combinations is described. Chromatography was carried on C-18 column by gradient elution with two mobile phase components: mobile phase (A) comprising of 80% of 10 mM acetate buffer adjusted to pH 3.5 with glacial acetic acid and 20% methanol and mobile phase (B) comprising of 50% acetonitrile with 50% isopropyl alcohol. Mobile phase was pumped at a flow rate of 0.6 ml min −1 and UV detection was employed at 270 nm. The average retention times for lamivudine, stavudine and nevirapine were 5.9, 8.8 and 14.2 min, respectively. The calibration curves were linear ( r > 0.999) in the range for each analyte. The method is accurate and precise with recoveries of lamivudine in the range of 98.7–100.4%, 99.2–100.6% for stavudine and 98.3–100.3% for nevirapine. No spectral or chromatographic interferences from the tablet excipients were found. This method which is rapid, simple and does not require any separation process has been successfully applied to the assay of commercial fixed dose formulations.

Development and Validation of LC Coupled with SPE for Simultaneous Determination of Lamivudine, Oxymatrine and its Active Metabolite Matrine in Dog Plasma

A simple and highly selective method, based upon solid-phase extraction (SPE), ion-pair HPLC and UV absorbance detection, was developed and validated to determine lamivudine, oxymatrine and its active metabolite matrine in dog plasma. The analytes and famotidine (internal standard) were simultaneously extracted from plasma samples by SPE, and separated on a C18 column. The mobile phase consisted of acetonitrile-water (13:87, v/v, 5 mmol L−1 sodium heptanesulfonate, at pH 3.2). The lower limit of quantification of the method was 0.1 mg L−1 for these analytes. The linear calibration curves of the analytes were obtained in the concentration range of 0.1–40 mg L−1. This method was successfully applied to the quantitative determination of plasma concentration of lamivudine, oxymatrine and its active metabolite matrine in dogs after single oral co-administration of 5.0 mg kg−1 lamivudine and 30.0 mg kg−1 oxymatrine.

Simultaneous determination of lamivudine and zidovudine concentrations in human seminal plasma using high-performance liquid chromatography and tandem mass spectrometry

A HPLC–MS–MS method was developed and validated to measure lamivudine and zidovudine simultaneously in small volumes of human seminal plasma. Sample preparation was simple and rapid, requiring 25 μl of sample, the use of isotopically labeled lamivudine and zidovudine as internal standards and ultrafiltration through a molecular mass cut-off membrane. Lamivudine and its internal standard were separated from zidovudine and its internal standard with isocratic HPLC. Detection was carried out using tandem mass spectrometry. This validated method was used to analyze seminal samples obtained from six HIV-positive patients prescribed lamivudine and zidovudine.