Roop Khar - Academia.edu (original) (raw)

Papers by Roop Khar

Research paper thumbnail of Development of oral sustained-release formulation of isoniazid/alginate/chitosan-blend microspheres for intestinal delivery

Research paper thumbnail of Anticonvulsant evaluation of safranal in pentylenetetrazole-induced status epilepticus in mice

Research paper thumbnail of Potential prospects of chitosan derivative trimethyl chitosan chloride (TMC) as a polymeric absorption enhancer: synthesis, characterization and applications

Journal of Pharmacy and Pharmacology, 2008

Research paper thumbnail of Potential prospects of chitosan derivative trimethyl chitosan chloride (TMC) as a polymeric absorption enhancer: synthesis, characterization and applications

Research paper thumbnail of Validated spectrophotometric methods for the estimation of moxifloxacin in bulk and pharmaceutical formulations

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2007

New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were develop... more New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were developed and validated for the estimation of moxifloxacin in bulk and pharmaceutical formulations. Moxifloxacin was estimated at 296 nm in 0.1N hydrochloric acid (pH 1.2) and at 289 nm in phosphate buffer (pH 7.4). Beer's law was obeyed in the concentration range of 1-12 microg ml(-1) (r2=0.9999) in hydrochloric acid and 1-14 microg ml(-1) (r2=0.9998) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.63 x 10(4) l mol(-1) cm(-1) and 9.5 ng cm(-2)/0.001 A in hydrochloric acid; and 4.08 x 10(4) l mol(-1) cm(-1) and 10.8 ng cm(-2)/0.001 A in phosphate buffer media, respectively indicating the high sensitivity of the proposed methods. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.0402, 0.1217 microg ml(-1) in hydrochloric acid and 0.0384, 0.1163 microg ml(-1) in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of moxifloxacin in pharmaceutical formulations (tablets, i.v. infusions, eye drops and polymeric nanoparticles). The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation <2%), while being simple, cheap and less time consuming and hence can be suitably applied for the estimation of moxifloxacin in different dosage forms and dissolution studies.

Research paper thumbnail of Stability indicating high-performance thin-layer chromatographic determination of gatifloxacin as bulk drug and from polymeric nanoparticles

Research paper thumbnail of Simple, sensitive, selective and validated spectrophotometric methods for the estimation of a biomarker trigonelline from polyherbal gels

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2007

Simple, accurate, reproducible, selective, sensitive and cost effective UV-spectrophotometric met... more Simple, accurate, reproducible, selective, sensitive and cost effective UV-spectrophotometric methods were developed and validated for the estimation of trigonelline in bulk and pharmaceutical formulations. Trigonelline was estimated at 265 nm in deionised water and at 264 nm in phosphate buffer (pH 4.5). Beer's law was obeyed in the concentration ranges of 1-20microg mL(-1) (r2=0.9999) in deionised water and 1-24 microg mL(-1) (r2=0.9999) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.04 x 10(3)L mol(-1)cm(-1) and 0.0422 microg cm(-2)/0.001A in deionised water; and 3.05 x 10(3)L mol(-1)cm(-1) and 0.0567 microg cm(-2)/0.001A in phosphate buffer media, respectively. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.12 and 0.37 microg mL(-1) in deionised water and 0.13 and 0.40 microg mL(-1) in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of trigonelline in pharmaceutical formulations (vaginal tablets and bioadhesive vaginal gels). The results demonstrated that the procedure is accurate, precise, specific and reproducible (percent relative standard deviation <2%), while being simple and less time consuming and hence can be suitably applied for the estimation of trigonelline in different dosage forms and dissolution studies.

Research paper thumbnail of Retraction: An HPTLC Method for the Determination of Minocycline in Human Plasma, Saliva, and Gingival Fluid after Single Step Liquid Extraction

Analytical Sciences, 2009

Page 1. 950 ANALYTICAL SCIENCES JULY 2009, VOL. 25 Retraction: An HPTLC Method for the Determinat... more Page 1. 950 ANALYTICAL SCIENCES JULY 2009, VOL. 25 Retraction: An HPTLC Method for the Determination of Minocycline in Human Plasma, Saliva, and Gingival Fluid after Single Step Liquid Extraction Nilu JAIN,† Gaurav ...

Research paper thumbnail of An HPTLC Method for the Determination of Minocycline in Human Plasma, Saliva, and Gingival Fluid after Single Step Liquid Extraction

Analytical Sciences, 2009

A rapid, sensitive and specific high-performance thin-layer chromatographic (HPTLC) method was de... more A rapid, sensitive and specific high-performance thin-layer chromatographic (HPTLC) method was developed and validated for determination of minocycline in human plasma, saliva, and gingival fluid samples. Densitometric analysis of minocycline was carried out at 345 nm after single step extraction with methanol. The method uses TLC aluminium plates pre-coated with silica gel 60F-254 as a stationary phase and methanol-acetonitrile-isopropyl alcohol-water (5:4:0.5:0.5, v/v/v/v) as mobile phase. In all the three matrices, the calibration curve was linear (r(2) >/= 0.9958) in the tested range of 100 - 1200 ng spot(-1) with a limit of quantification of 15.4 ng spot(-1). Drug recovery from plasma, saliva and gingival fluid averaged 97.7%. Intra- and inter-day accuracies, determined at three different concentrations, were 95.08 to 100.6% and the corresponding precision (% CV) values were < 4.61%. In all the three matrices, rapid degradation of drug occurred and the half-life of drug ranged from 9.9 to 16.1 h at 4 degrees C and from 6.3 to 11.5 h at 20 degrees C. Frozen at -20 degrees C, this drug was stable for at least 2 months and can tolerate two freeze-thaw cycles without losses higher than 10%. The method's ability to quantify minocycline with precision, accuracy and sensitivity makes it useful in pharmacokinetic studies.

Research paper thumbnail of Role of CD44 in tumour progression and strategies for targeting

Journal of Drug Targeting, 2012

CD44 or hyaluronan receptor is a transmembrane receptor associated with aggressive tumour growth,... more CD44 or hyaluronan receptor is a transmembrane receptor associated with aggressive tumour growth, proliferation, and metastasis. In normal physiology, this receptor has a crucial role in cell adhesion, inflammation, and repair processes. However, many tumour cells over-express this receptor and abuse it to become progressive and perpetual units. The article comments from common functioning of the CD44 receptor, to its diabolic multi-dimensional effects in promotion of malignant cells. It also illuminates the relations of CD44 endorsed processes with other biomolecular events in cancer progression. In an end, the review focuses comprehensively at ongoing researches to exploit the CD44 over-expression as a probable target in treatment, management, and diagnosis of malignancy.

Research paper thumbnail of Concurrent determination of topotecan and model permeability markers (atenolol, antipyrine, propranolol and furosemide) by reversed phase liquid chromatography: Utility in Caco-2 intestinal absorption studies

Journal of Chromatography B, 2007

Research paper thumbnail of Novel formulation approaches for optimising delivery of anticancer drugs based on P-glycoprotein modulation

Drug Discovery Today, 2009

Research paper thumbnail of Liposomes for liver scintigraphy

Journal of Liposome Research, 1994

ABSTRACT

Research paper thumbnail of Effect of P-glycoprotein inhibitor, verapamil, on oral bioavailability and pharmacokinetics of irinotecan in rats

European Journal of Pharmaceutical Sciences, 2009

Research paper thumbnail of Development and validation of reversed phase liquid chromatographic method utilizing ultraviolet detection for quantification of irinotecan (CPT11) and its active metabolite, SN38, in rat plasma and bile samples: Application to pharmacokinetic studies

Talanta, 2008

A new, simple, sensitive and specific reversed-phase high performance liquid chromatographic (HPL... more A new, simple, sensitive and specific reversed-phase high performance liquid chromatographic (HPLC) method using ultraviolet detection was developed and validated for the analysis of CPT-11 (λmax=254nm, 365nm) and its major active metabolite, SN-38 (λmax=380nm) in rat plasma and bile. The sample pre-treatment from plasma involved a single protein precipitation step with cold acetonitrile. In case of bile, liquid–liquid extraction with

Research paper thumbnail of Pre-clinical evidence for altered absorption and biliary excretion of irinotecan (CPT-11) in combination with quercetin: Possible contribution of P-glycoprotein

Research paper thumbnail of A STABILITY INDICATING HPTLC METHOD FOR THE ANALYSIS OF IRINOTECAN IN BULK DRUG AND MARKETED INJECTABLES

Journal of Liquid Chromatography & Related Technologies, 2011

... K. Khar a , Md. Faiyazuddin a , Farhan J. Ahmad a , Zeenat Iqbal a & ... more ... K. Khar a , Md. Faiyazuddin a , Farhan J. Ahmad a , Zeenat Iqbal a & Manu Jaggi b ... View all references , 15 15. Ali , J. ; Ali , N. ; Sultana , Y. ; Baboota , S. ; Faiyaz , S. Development and Validation of a Stability-Indicating HPTLC Method for Analysis of Antitubercular Drugs . ...

Research paper thumbnail of Emerging Significance of Flavonoids as P-Glycoprotein Inhibitors in Cancer Chemotherapy

Chemotherapy forms the mainstay of cancer treatment particularly for patients who do not respond ... more Chemotherapy forms the mainstay of cancer treatment particularly for patients who do not respond to local excision or radiation treatment. However, cancer treatment by drugs is seriously limited by P-glycoprotein (P-gp) associated multi-drug resistance (MDR) in various tumor cells. On the other hand, it is now widely recognized that P-gp also influences drug transport across various biological membranes. P-gp transporter

Research paper thumbnail of A validated HPTLC method for determination of tea tree oil from cosmeceutical formulations

Journal of Pharmaceutical and Biomedical Analysis, 2005

Research paper thumbnail of Tea tree oil concentration in follicular casts after topical delivery: Determination by high-performance thin layer chromatography using a perfused bovine udder model

Journal of Pharmaceutical Sciences, 2005

Tea tree oil, a popular antimicrobial agent is recommended for the treatment of acne vulgaris, a ... more Tea tree oil, a popular antimicrobial agent is recommended for the treatment of acne vulgaris, a disease of the pilosebaceous unit. Tea tree oil formulations (colloidal bed, microemulsion, multiple emulsion, and liposomal dispersion containing 5% w/w tea tree oil) were applied to bovine udder skin. The follicular uptake of tea tree oil upon application was determined by a cyanoacrylate method. Tea tree oil was determined by quantifying terpinen-4-ol content using high-performance thin layer chromatography. The accumulation of tea tree oil in the follicular casts was 0.43 +/- 0.01, 0.41 +/- 0.009, 0.21 +/- 0.006, and 0.16 +/- 0.005 percentage by weight (milligram oil/gram of sebum plug) for microemulsion, liposomal dispersion, multiple emulsion, and colloidal bed, respectively. This is the first study of its kind to quantify tea tree oil concentration in the follicles.

Research paper thumbnail of Development of oral sustained-release formulation of isoniazid/alginate/chitosan-blend microspheres for intestinal delivery

Research paper thumbnail of Anticonvulsant evaluation of safranal in pentylenetetrazole-induced status epilepticus in mice

Research paper thumbnail of Potential prospects of chitosan derivative trimethyl chitosan chloride (TMC) as a polymeric absorption enhancer: synthesis, characterization and applications

Journal of Pharmacy and Pharmacology, 2008

Research paper thumbnail of Potential prospects of chitosan derivative trimethyl chitosan chloride (TMC) as a polymeric absorption enhancer: synthesis, characterization and applications

Research paper thumbnail of Validated spectrophotometric methods for the estimation of moxifloxacin in bulk and pharmaceutical formulations

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2007

New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were develop... more New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were developed and validated for the estimation of moxifloxacin in bulk and pharmaceutical formulations. Moxifloxacin was estimated at 296 nm in 0.1N hydrochloric acid (pH 1.2) and at 289 nm in phosphate buffer (pH 7.4). Beer's law was obeyed in the concentration range of 1-12 microg ml(-1) (r2=0.9999) in hydrochloric acid and 1-14 microg ml(-1) (r2=0.9998) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.63 x 10(4) l mol(-1) cm(-1) and 9.5 ng cm(-2)/0.001 A in hydrochloric acid; and 4.08 x 10(4) l mol(-1) cm(-1) and 10.8 ng cm(-2)/0.001 A in phosphate buffer media, respectively indicating the high sensitivity of the proposed methods. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.0402, 0.1217 microg ml(-1) in hydrochloric acid and 0.0384, 0.1163 microg ml(-1) in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of moxifloxacin in pharmaceutical formulations (tablets, i.v. infusions, eye drops and polymeric nanoparticles). The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation <2%), while being simple, cheap and less time consuming and hence can be suitably applied for the estimation of moxifloxacin in different dosage forms and dissolution studies.

Research paper thumbnail of Stability indicating high-performance thin-layer chromatographic determination of gatifloxacin as bulk drug and from polymeric nanoparticles

Research paper thumbnail of Simple, sensitive, selective and validated spectrophotometric methods for the estimation of a biomarker trigonelline from polyherbal gels

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2007

Simple, accurate, reproducible, selective, sensitive and cost effective UV-spectrophotometric met... more Simple, accurate, reproducible, selective, sensitive and cost effective UV-spectrophotometric methods were developed and validated for the estimation of trigonelline in bulk and pharmaceutical formulations. Trigonelline was estimated at 265 nm in deionised water and at 264 nm in phosphate buffer (pH 4.5). Beer's law was obeyed in the concentration ranges of 1-20microg mL(-1) (r2=0.9999) in deionised water and 1-24 microg mL(-1) (r2=0.9999) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.04 x 10(3)L mol(-1)cm(-1) and 0.0422 microg cm(-2)/0.001A in deionised water; and 3.05 x 10(3)L mol(-1)cm(-1) and 0.0567 microg cm(-2)/0.001A in phosphate buffer media, respectively. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.12 and 0.37 microg mL(-1) in deionised water and 0.13 and 0.40 microg mL(-1) in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of trigonelline in pharmaceutical formulations (vaginal tablets and bioadhesive vaginal gels). The results demonstrated that the procedure is accurate, precise, specific and reproducible (percent relative standard deviation <2%), while being simple and less time consuming and hence can be suitably applied for the estimation of trigonelline in different dosage forms and dissolution studies.

Research paper thumbnail of Retraction: An HPTLC Method for the Determination of Minocycline in Human Plasma, Saliva, and Gingival Fluid after Single Step Liquid Extraction

Analytical Sciences, 2009

Page 1. 950 ANALYTICAL SCIENCES JULY 2009, VOL. 25 Retraction: An HPTLC Method for the Determinat... more Page 1. 950 ANALYTICAL SCIENCES JULY 2009, VOL. 25 Retraction: An HPTLC Method for the Determination of Minocycline in Human Plasma, Saliva, and Gingival Fluid after Single Step Liquid Extraction Nilu JAIN,† Gaurav ...

Research paper thumbnail of An HPTLC Method for the Determination of Minocycline in Human Plasma, Saliva, and Gingival Fluid after Single Step Liquid Extraction

Analytical Sciences, 2009

A rapid, sensitive and specific high-performance thin-layer chromatographic (HPTLC) method was de... more A rapid, sensitive and specific high-performance thin-layer chromatographic (HPTLC) method was developed and validated for determination of minocycline in human plasma, saliva, and gingival fluid samples. Densitometric analysis of minocycline was carried out at 345 nm after single step extraction with methanol. The method uses TLC aluminium plates pre-coated with silica gel 60F-254 as a stationary phase and methanol-acetonitrile-isopropyl alcohol-water (5:4:0.5:0.5, v/v/v/v) as mobile phase. In all the three matrices, the calibration curve was linear (r(2) >/= 0.9958) in the tested range of 100 - 1200 ng spot(-1) with a limit of quantification of 15.4 ng spot(-1). Drug recovery from plasma, saliva and gingival fluid averaged 97.7%. Intra- and inter-day accuracies, determined at three different concentrations, were 95.08 to 100.6% and the corresponding precision (% CV) values were < 4.61%. In all the three matrices, rapid degradation of drug occurred and the half-life of drug ranged from 9.9 to 16.1 h at 4 degrees C and from 6.3 to 11.5 h at 20 degrees C. Frozen at -20 degrees C, this drug was stable for at least 2 months and can tolerate two freeze-thaw cycles without losses higher than 10%. The method's ability to quantify minocycline with precision, accuracy and sensitivity makes it useful in pharmacokinetic studies.

Research paper thumbnail of Role of CD44 in tumour progression and strategies for targeting

Journal of Drug Targeting, 2012

CD44 or hyaluronan receptor is a transmembrane receptor associated with aggressive tumour growth,... more CD44 or hyaluronan receptor is a transmembrane receptor associated with aggressive tumour growth, proliferation, and metastasis. In normal physiology, this receptor has a crucial role in cell adhesion, inflammation, and repair processes. However, many tumour cells over-express this receptor and abuse it to become progressive and perpetual units. The article comments from common functioning of the CD44 receptor, to its diabolic multi-dimensional effects in promotion of malignant cells. It also illuminates the relations of CD44 endorsed processes with other biomolecular events in cancer progression. In an end, the review focuses comprehensively at ongoing researches to exploit the CD44 over-expression as a probable target in treatment, management, and diagnosis of malignancy.

Research paper thumbnail of Concurrent determination of topotecan and model permeability markers (atenolol, antipyrine, propranolol and furosemide) by reversed phase liquid chromatography: Utility in Caco-2 intestinal absorption studies

Journal of Chromatography B, 2007

Research paper thumbnail of Novel formulation approaches for optimising delivery of anticancer drugs based on P-glycoprotein modulation

Drug Discovery Today, 2009

Research paper thumbnail of Liposomes for liver scintigraphy

Journal of Liposome Research, 1994

ABSTRACT

Research paper thumbnail of Effect of P-glycoprotein inhibitor, verapamil, on oral bioavailability and pharmacokinetics of irinotecan in rats

European Journal of Pharmaceutical Sciences, 2009

Research paper thumbnail of Development and validation of reversed phase liquid chromatographic method utilizing ultraviolet detection for quantification of irinotecan (CPT11) and its active metabolite, SN38, in rat plasma and bile samples: Application to pharmacokinetic studies

Talanta, 2008

A new, simple, sensitive and specific reversed-phase high performance liquid chromatographic (HPL... more A new, simple, sensitive and specific reversed-phase high performance liquid chromatographic (HPLC) method using ultraviolet detection was developed and validated for the analysis of CPT-11 (λmax=254nm, 365nm) and its major active metabolite, SN-38 (λmax=380nm) in rat plasma and bile. The sample pre-treatment from plasma involved a single protein precipitation step with cold acetonitrile. In case of bile, liquid–liquid extraction with

Research paper thumbnail of Pre-clinical evidence for altered absorption and biliary excretion of irinotecan (CPT-11) in combination with quercetin: Possible contribution of P-glycoprotein

Research paper thumbnail of A STABILITY INDICATING HPTLC METHOD FOR THE ANALYSIS OF IRINOTECAN IN BULK DRUG AND MARKETED INJECTABLES

Journal of Liquid Chromatography & Related Technologies, 2011

... K. Khar a , Md. Faiyazuddin a , Farhan J. Ahmad a , Zeenat Iqbal a & ... more ... K. Khar a , Md. Faiyazuddin a , Farhan J. Ahmad a , Zeenat Iqbal a & Manu Jaggi b ... View all references , 15 15. Ali , J. ; Ali , N. ; Sultana , Y. ; Baboota , S. ; Faiyaz , S. Development and Validation of a Stability-Indicating HPTLC Method for Analysis of Antitubercular Drugs . ...

Research paper thumbnail of Emerging Significance of Flavonoids as P-Glycoprotein Inhibitors in Cancer Chemotherapy

Chemotherapy forms the mainstay of cancer treatment particularly for patients who do not respond ... more Chemotherapy forms the mainstay of cancer treatment particularly for patients who do not respond to local excision or radiation treatment. However, cancer treatment by drugs is seriously limited by P-glycoprotein (P-gp) associated multi-drug resistance (MDR) in various tumor cells. On the other hand, it is now widely recognized that P-gp also influences drug transport across various biological membranes. P-gp transporter

Research paper thumbnail of A validated HPTLC method for determination of tea tree oil from cosmeceutical formulations

Journal of Pharmaceutical and Biomedical Analysis, 2005

Research paper thumbnail of Tea tree oil concentration in follicular casts after topical delivery: Determination by high-performance thin layer chromatography using a perfused bovine udder model

Journal of Pharmaceutical Sciences, 2005

Tea tree oil, a popular antimicrobial agent is recommended for the treatment of acne vulgaris, a ... more Tea tree oil, a popular antimicrobial agent is recommended for the treatment of acne vulgaris, a disease of the pilosebaceous unit. Tea tree oil formulations (colloidal bed, microemulsion, multiple emulsion, and liposomal dispersion containing 5% w/w tea tree oil) were applied to bovine udder skin. The follicular uptake of tea tree oil upon application was determined by a cyanoacrylate method. Tea tree oil was determined by quantifying terpinen-4-ol content using high-performance thin layer chromatography. The accumulation of tea tree oil in the follicular casts was 0.43 +/- 0.01, 0.41 +/- 0.009, 0.21 +/- 0.006, and 0.16 +/- 0.005 percentage by weight (milligram oil/gram of sebum plug) for microemulsion, liposomal dispersion, multiple emulsion, and colloidal bed, respectively. This is the first study of its kind to quantify tea tree oil concentration in the follicles.