Haffsah Iqbal | Imperial College London (original) (raw)
Papers by Haffsah Iqbal
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h r o m a
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h r o m a
A reversed-phase high performance liquid chromatography (RP-HPLC) method with UV detection is des... more A reversed-phase high performance liquid chromatography (RP-HPLC) method with UV detection is described for the simultaneous determination of metronidazole and miconazole in pharmaceutical dosage forms. Chromatography was carried out on a C18 reversed-phase column, using a mixture of methanol Á/water (40'/60, v/v) as a mobile phase, at a flow rate of 1.0 ml min (1 . Sulfamethoxazole was used as an internal standard and detection was performed using a diode array detector at 254 nm. The method produced linear responses in the concentration ranges 10 Á/70 and 1 Á/20 mg ml (1 with detection limits 0.33 and 0.27 mg ml (1 for metronidazole and micanozole, respectively. This procedure was found to be convenient and reproducible for analysis of these drugs in ovule dosage forms. # 2002 É ditions scientifiques et médicales Elsevier SAS. All rights reserved. .tr (S.A. Ö zkan). Il Farmaco 57 (2002) 953 Á/957 www.elsevier.com/locate/farmac 0014-827X/02/$ -see front matter # 2002 É ditions scientifiques et médicales Elsevier SAS. All rights reserved. PII: S 0 0 1 4 -8 2 7 X ( 0 2 ) 0 1 2 9 6 -X
A simple and stability-indicating high performance liquid chromatographic method was developed an... more A simple and stability-indicating high performance liquid chromatographic method was developed and validated for the determination of miconazole nitrate in bulk and cream preparations. The extraction step for cream samples consisted in a warming, cooling and centrifugation procedure that assures the elimination of the lipophilic matrix component, in order to avoid further precipitation in the chromatographic system. Separation was achieved on a ZORBAX Eclipse XDB -C18 (4.6 mm × 150 mm, 5 m particle size) column, using a mobile phase consisting of water, methanol and acetonitrile, in a flow and solvent gradient elution for 15 min. The column was maintained at 25 • C and 10 L of solutions were injected. UV detection was performed at 232 nm, although employment of a diode array detector allowed selectivity confirmation by peak purity evaluation. The method was validated reaching satisfactory results for selectivity, precision and accuracy. Degradation products in naturally aged samples could be simultaneously evaluated, without interferences in the quantitative analysis. .ar (M.M. De Zan).
Dapivirine, a non-nucleoside reverse transcriptase inhibitor, is being currently used for the dev... more Dapivirine, a non-nucleoside reverse transcriptase inhibitor, is being currently used for the development of potential anti-HIV microbicide formulations and delivery systems. A new high-performance liquid chromatography (HPLC) method with UV detection was developed for the assay of this drug in different biological matrices, namely cell lysates, receptor media from permeability experiments and homogenates of mucosal tissues. The method used a reversed-phase C18 column with a mobile phase composed of trifluoroacetic acid solution (0.1%, v/v) and acetonitrile in a gradient mode. Injection volume was 50 L and the flow rate 1 mL/min. The total run time was 12 min and UV detection was performed at 290 nm for dapivirine and the internal standard (IS) diphenylamine. A Box-Behnken experimental design was used to study different experimental variables of the method, namely the ratio of the mobile phase components and the gradient time, and their influence in responses such as the retention factor, tailing factor, and theoretical plates for dapivirine and the IS, as well as the peak resolution between both compounds. The optimized method was further validated and its usefulness assessed for in vitro and ex vivo experiments using dapivirine or dapivirine-loaded nanoparticles. The method showed to be selective, linear, accurate and precise in the range of 0.02-1.5 g/mL. Other chromatographic parameters, namely carry-over, lower limit of quantification (0.02 g/mL), limit of detection (0.006 g/mL), recovery (equal or higher than 90.7%), and sample stability at different storage conditions, were also determined and found adequate for the intended purposes. The method was successfully used for cell uptake assays and permeability studies across cell monolayers and pig genital mucosal tissues. Overall, the proposed method provides a simple, versatile and reliable way for studying the behavior of dapivirine in different biological matrices and assessing its potential as an anti-HIV microbicide drug.
Acta Crystallographica Section E-structure Reports Online, 2010
Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.011 Å; disorder in main res... more Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.011 Å; disorder in main residue; R factor = 0.053; wR factor = 0.209; data-to-parameter ratio = 8.0.
Acta Crystallographica Section E-structure Reports Online, 2010
Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.011 Å; disorder in main res... more Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.011 Å; disorder in main residue; R factor = 0.053; wR factor = 0.209; data-to-parameter ratio = 8.0.
Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.011 Å; disorder in main res... more Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.011 Å; disorder in main residue; R factor = 0.053; wR factor = 0.209; data-to-parameter ratio = 8.0.
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h r o m a
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h r o m a
A reversed-phase high performance liquid chromatography (RP-HPLC) method with UV detection is des... more A reversed-phase high performance liquid chromatography (RP-HPLC) method with UV detection is described for the simultaneous determination of metronidazole and miconazole in pharmaceutical dosage forms. Chromatography was carried out on a C18 reversed-phase column, using a mixture of methanol Á/water (40'/60, v/v) as a mobile phase, at a flow rate of 1.0 ml min (1 . Sulfamethoxazole was used as an internal standard and detection was performed using a diode array detector at 254 nm. The method produced linear responses in the concentration ranges 10 Á/70 and 1 Á/20 mg ml (1 with detection limits 0.33 and 0.27 mg ml (1 for metronidazole and micanozole, respectively. This procedure was found to be convenient and reproducible for analysis of these drugs in ovule dosage forms. # 2002 É ditions scientifiques et médicales Elsevier SAS. All rights reserved. .tr (S.A. Ö zkan). Il Farmaco 57 (2002) 953 Á/957 www.elsevier.com/locate/farmac 0014-827X/02/$ -see front matter # 2002 É ditions scientifiques et médicales Elsevier SAS. All rights reserved. PII: S 0 0 1 4 -8 2 7 X ( 0 2 ) 0 1 2 9 6 -X
A simple and stability-indicating high performance liquid chromatographic method was developed an... more A simple and stability-indicating high performance liquid chromatographic method was developed and validated for the determination of miconazole nitrate in bulk and cream preparations. The extraction step for cream samples consisted in a warming, cooling and centrifugation procedure that assures the elimination of the lipophilic matrix component, in order to avoid further precipitation in the chromatographic system. Separation was achieved on a ZORBAX Eclipse XDB -C18 (4.6 mm × 150 mm, 5 m particle size) column, using a mobile phase consisting of water, methanol and acetonitrile, in a flow and solvent gradient elution for 15 min. The column was maintained at 25 • C and 10 L of solutions were injected. UV detection was performed at 232 nm, although employment of a diode array detector allowed selectivity confirmation by peak purity evaluation. The method was validated reaching satisfactory results for selectivity, precision and accuracy. Degradation products in naturally aged samples could be simultaneously evaluated, without interferences in the quantitative analysis. .ar (M.M. De Zan).
Dapivirine, a non-nucleoside reverse transcriptase inhibitor, is being currently used for the dev... more Dapivirine, a non-nucleoside reverse transcriptase inhibitor, is being currently used for the development of potential anti-HIV microbicide formulations and delivery systems. A new high-performance liquid chromatography (HPLC) method with UV detection was developed for the assay of this drug in different biological matrices, namely cell lysates, receptor media from permeability experiments and homogenates of mucosal tissues. The method used a reversed-phase C18 column with a mobile phase composed of trifluoroacetic acid solution (0.1%, v/v) and acetonitrile in a gradient mode. Injection volume was 50 L and the flow rate 1 mL/min. The total run time was 12 min and UV detection was performed at 290 nm for dapivirine and the internal standard (IS) diphenylamine. A Box-Behnken experimental design was used to study different experimental variables of the method, namely the ratio of the mobile phase components and the gradient time, and their influence in responses such as the retention factor, tailing factor, and theoretical plates for dapivirine and the IS, as well as the peak resolution between both compounds. The optimized method was further validated and its usefulness assessed for in vitro and ex vivo experiments using dapivirine or dapivirine-loaded nanoparticles. The method showed to be selective, linear, accurate and precise in the range of 0.02-1.5 g/mL. Other chromatographic parameters, namely carry-over, lower limit of quantification (0.02 g/mL), limit of detection (0.006 g/mL), recovery (equal or higher than 90.7%), and sample stability at different storage conditions, were also determined and found adequate for the intended purposes. The method was successfully used for cell uptake assays and permeability studies across cell monolayers and pig genital mucosal tissues. Overall, the proposed method provides a simple, versatile and reliable way for studying the behavior of dapivirine in different biological matrices and assessing its potential as an anti-HIV microbicide drug.
Acta Crystallographica Section E-structure Reports Online, 2010
Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.011 Å; disorder in main res... more Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.011 Å; disorder in main residue; R factor = 0.053; wR factor = 0.209; data-to-parameter ratio = 8.0.
Acta Crystallographica Section E-structure Reports Online, 2010
Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.011 Å; disorder in main res... more Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.011 Å; disorder in main residue; R factor = 0.053; wR factor = 0.209; data-to-parameter ratio = 8.0.
Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.011 Å; disorder in main res... more Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.011 Å; disorder in main residue; R factor = 0.053; wR factor = 0.209; data-to-parameter ratio = 8.0.