Zidovudine

A high throughput, sensitive, selective, and rugged liquid chromatography coupled with mass spectrometry (LC-MS/MS) method for the quantification of Zidovudine, Lamivudine and Nevirapine, in human plasma was developed and validated.  The analytes were extracted from plasma by solid phase extraction technique using Waters Oasis HLB 96 well plate 30 µm (30 mg). Isocratic  elution  of  Zidovudine, Lamivudine and Nevirapine  were  achieved  in  3 min  using  ACE, C18, 4.6 X 150mm, 5µ column having a mobile phase of 0.1% formic acid: Methanol 30: 70 v/v. The flow rate was 0.7 mL/min at a column temperature of 35 ± 5°C. Electron spray ionization technique in positive mode was selected to improve the selectivity and sensitivity required for this application. The retention times of Zidovudine, Lamivudine and Nevirapine were 1.5, 1.2, and 1.7 min, respectively. The method was validated for linearity, precision, accuracy, specificity, sensitivity, matrix effect, dilution integrity, ruggedness, reinjection reproducibility, and stability. The assay produced linear calibration curves over the concentration range for Zidovudine, Lamivudine and Nevirapine in the ranges of 5 to 1500, 5 to  1500 and 10 to 3000 ng/mL respectively with correlation coefficients greater than 0.9963 using a 1/x2  weighted least square regression analysis of standard plots associated with eight-point calibration standards. The precision and mean accuracy were within the acceptable limits.

An accurate, precise and reproducible high performance liquid chromatographic method was developed for the simultaneous estimation of lamivudine, zidovudine and nevirapine in pharmaceutical dosage forms. Phenomenex C18 column (250 x 4.6 mm; 5µ) was employed for the separation of drugs. A mixture of 0.02 M trichloroacetic acid (6.8 pH) and methanol in the ratio of 40:60 v/v was used as the mobile phase and pumped at a flow rate of 1ml/min. The detection wavelength was set at 265 nm. The linearity of quantification was observed in the range of 7.5-112.5, 10-150 and 15-225 μg/ml for lamivudine, zidovudine and nevirapine respectively. The proposed method was validated according to ICH guidelines. The method was found to be suitable for simultaneous and accurate determination of these drugs in tablet dosage forms without any interference from the excipients.

An accurate, precise and reproducible high performance liquid chromatographic method was developed for quantitative estimation of abacavir, lamivudine and zidovudine simultaneously in tablet dosage forms. Separation of the drugs was achieved within 15.0 min on a Hichrom RP-select B column (250 x 4.6 mm; 5µ) by gradient elution using mixtures of 0.02M ammonium acetate and methanol as the mobile phase. The analytes in the eluate were monitored at 250 nm. The retention times obtained for abacavir, lamivudine and zidovudine were 12.172, 1.884 and 4.378 min respectively. The calibration curves were linear over the range of 25-200 µg/mL for abacavir, 12.5-100 µg/mL for lamivudine and 25-200 µg/mL for zidovudine. The performance of the method was validated according to ICH guidelines. The method was found to be suitable for accurate determination of these drugs in tablet dosage forms without any interference from the excipients or endogenous substances. Key words: Abacavir, Lamivudine, Zidovudine, Determination, HPLC, Gradient elution.

  The objective of the present study was to prepare and evaluate gastroretentive effervescent floating drug delivery system containing Zidovudine as a model drug. Zidovudine is the first approved compound for the treatment of AIDS; however the main limitation to therapeutic effectiveness of zidovudine is its dose-dependent toxicity, short biological half-life and poor bioavailability. Zidovudine gastroretentive effervescent floating tablets were prepared by direct compression method. Sodium bicarbonate and citric acid were incorporated as gas-generating agents. Drug compatibility with excipients was checked by DSC and FTIR studies revealed that, there was no incompatibility of the drug with the excipients used. The results of in-vitro buoyancy time and lag time study, the values of in-vitro buoyancy time ranges from 180 to 870 min where as floating lag time ranges from 2.11 to 51.36 min. The formulations prepared with carbopol have longer floating lag times. The formulation GREFT-6 shows the lag time 2.11 min and buoyancy time 870 min. The release of Zidovudine from all the formulations ranges from 45.05 - 64.96 % drug released at the end of 6 hrs. The formulations GREFT-1 and GREFT-2 shows 90 % of drug release within 10 hrs. The formulations GREFT-3 to GREFT-7 shows drug release ranges from 86.17 - 96.65 % at the end of 12 hrs. The results were revealed that as the concentration of carbopol increases, there is decrease in the drug release and floating time has been increased. The formulation GREFT-6 containing Carbopol 934P 100 mg showed the controlled drug release when compare to other formulations. The stability study conducted as per the ICH guidelines and the formulations were found to be stable. From the above studies, it has been observed that effervescent based floating drug delivery system is a promising approach to achieve controlled release behavior. Key wards: Zidovudine, HPMC K4M, carbopol, floating tablets, effervescent.