Mixed metal halide perovskites are gaining paramount interest due to efficient band gap tenabilit... more Mixed metal halide perovskites are gaining paramount interest due to efficient band gap tenability and improved optical properties compared to their single metal halide perovskites. It is thus valuable to investigate compositional changes in lead halide perovskites to explore energy changes. Herein, we report the synthesis of a lead to lead free hybrid perovskite solid solution (CH 3 NH 3 Pb 1Àx Cu x Br 3) as nanoparticles and films. The increasing concentration of Cu 2+ ions in the site of the Pb 2+ ion in the perovskite shifted the diffraction peaks to a larger angle. Uniform spherically shaped nanoparticles were synthesized by a wet chemical method, the higher Cu 2+ concentration leads to agglomeration, producing sheet like morphologies. However, the deposition of thin films of CH 3 NH 3 Pb 1Àx Cu x Br 3 perovskite solid solution shows that well defined morphologies begin to appear with increasing concentrations of Cu 2+ in the perovskite structure. The as-prepared bulk lead free CH 3 NH 3 CuBr 3 perovskite shows a band gap of 1.65 eV. A blue shift in photoluminescence (PL) was observed with copper enriched hybrid perovskites.
Inorganic halide perovskite (CsPbX 3) nanostructures have gained considerable interest in recent ... more Inorganic halide perovskite (CsPbX 3) nanostructures have gained considerable interest in recent years owing to their enhanced stability and optoelectronic applications. Recent developments in the synthesis of nanostructures are reviewed. The impact of the precursor and ligand nature, temperature and growth time on the morphology and shape tuning of CsPbX 3 nanostructures is described in relation to their optical properties. The presynthetic and postsynthetic anion exchange strategies to retain pre-existing crystal phase and shape are discussed in this minireview.
The present study was undertaken to evaluate the effect of glyceryl monostearate (GMS) and steari... more The present study was undertaken to evaluate the effect of glyceryl monostearate (GMS) and stearic acid (SA) on the release profile of gliclazide from the matrix. Matrix tablets for the controlled delivery of gliclazide were prepared by hot melt method using pure and blended mixture of glyceryl monostearate and stearic acid in different drug to polymer and polymer to polymer ratios. In vitro release characteristics of gliclazide from these hydrophobic matrices were studied over 8 h in phosphate buffer media of pH 7.4. The release kinetics of drug was evaluated for zero order, first order, Higuchi and Peppas kinetic models. It was observed that the release of drug from the matrix was greatly retarded by GMS and retarding effect increased with increasing polymer to drug ratios. On the other hand SA appeared to channel the drug from the wax matrix and release was greatly increased with increasing polymer to drug ratios. The kinetic evaluation of release profile indicated that the Higuchi model was the most appropriate model for describing the release profile of gliclazide. The application of Peppas biexponential equation indicated that non-Fickian release was the predominant mechanism of drug release. The FTIR results showed no interaction between the drug and the polymers and DSC results indicated that both the drug and polymers are in amorphous state and no significant complexes were formed. The results indicated that proper selection of drug to polymer and polymer to polymer ratios were important in order to achieve the desired dissolution profile in these matrix tablets.
The aim of this study was to formulate ethyl cellulose (EC) microparticles for sustained release ... more The aim of this study was to formulate ethyl cellulose (EC) microparticles for sustained release of nimesulide and study the effect of processing variables, drug to polymer ratio and also study the drug polymer compatibility. The microparticles were prepared by coacervation (temperature change) technique. Physical properties, such as particle size, entrapment efficiency, release pattern and morphological characteristics were investigated by in vitro dissolution, SEM, FTIR, XRD, DSC and TGA in order to optimize the formulation of the microparticles. With the increase of polymer concentration there was an increase in size and drug entrapment efficiency of microparticles. There was a decrease in size and nonlinear change in entrapment efficiency with the increase of stirring speed and time. The release of drug from microparticles was anomalous diffusion. It was confirmed that there is no strong chemical interaction between drug and polymer except the change in crystal habit and polymorphism. Ethyl cellulose microparticles containing nimesulide are suitable for controlled release devising.
N ew formulations of microparticles for Tramadol HCl (TmH) controlled-release were developed and ... more N ew formulations of microparticles for Tramadol HCl (TmH) controlled-release were developed and evaluated. These microparticles with controlled-release characteristics were prepared by non-solvent addition technique. Ethyl cellulose (EC) a hydrophobic polymer was employed to control and extend the drug release process. Dichloromethane (DCM) was employed as solvent for polymer and paraffin oil as non-solvent which induced phase separation. Microparticles of different polymer concentrations M 1 (1:1), M 2 (1:2) and M 3 (1:3) were prepared. Among all these formulations, M 3 presented superior and desirable characteristics, i.e., 79% entrapment efficiency, good micromeritic properties, smooth morphology, and more sustained effect on cumulative release. Zero order, first order, Higuchi, Hixson-Crowell, and Korsmeyer-Peppas kinetic models were applied to assess the mechanism and pattern of drug release from microparticles. Release of TmH was best fitted to Higuchi model because it presented highest values of correlation coefficient (R 2 = 0.981) followed by zero-order kinetic model (R 2 = 0.899). FTIR, XRD, and DSC analyses ensured the chemical stability and integrity of TmH and EC in M 3 as no new bands were detected in FTIR spectra. Moreover the XRD patterns of TmH showed its reduced crystallinity and endothermic peak was observed at the glass transition temperature of EC in DSC spectra. M 3 sample was kept at 40ºC/75% RH for three months and its stability was evaluated by determining sample's in vitro release profile and drug assay.
African Journal of Pharmacy and Pharmacology, Oct 22, 2011
The purpose of this study was to assess bioequivalence of two marketed formulations of celecoxib ... more The purpose of this study was to assess bioequivalence of two marketed formulations of celecoxib capsules in healthy human male volunteers. The study was conducted according to a single dose, randomized sequence, open label, two-period and crossover design. Both test and reference formulations comprised labeled dose of 200 mg celecoxib and were administered to each subject after an overnight fasting on two treatment days separated by one week of washout period. After drug administration, blood samples were collected at predetermined time points for a period of 48 h. Plasma separated from blood was analyzed for celecoxib concentrations using validated reverse phase-high performance liquid chromatographic (RP-HPLC) method. Various pharmacokinetic parameters including C max , T max , AUC 0-t , AUC 0-∞ , T 1/2 and K el were determined from the plasma concentration for both formulations. C max , AUC 0-t and AUC 0-∞ , were evaluated for bioequivalence after log-transformation of data. The 90% confidence intervals for the ratio of C max (93.26 to 100.70%), AUC 0-t (87.00 to 117.50%) and AUC 0-∞ (86.49 to 118.56%), values for the test and reference products were within the acceptance range of 80 to 125%, proposed by Food and Drug Administration (FDA) and European Medicines Evaluation Agency (EMEA). Based on these statistical inferences, it was concluded that two formulations of celecoxib are bioequivalent in their rate and extent of absorption.
Environmental geochemistry and health, Jan 29, 2016
Hexachlorocyclohexane (HCH) isomers and dichlorodiphenyltrichloroethane (DDT) metabolites were an... more Hexachlorocyclohexane (HCH) isomers and dichlorodiphenyltrichloroethane (DDT) metabolites were analyzed in sediments of three different depths (0-10, 10-20 and 20-30 cm) collected from Kabul River, Pakistan, in February 2014. The occurrence levels, enantiomer fractions and potential ecological risk of these organochlorine pesticides (OCPs) were evaluated. The total concentrations of ∑HCHs and ∑DDTs in surface sediments ranged from 4.9-23.9 ng g(-1) and from 6.4-18.8 ng g(-1) (dry weight basis), respectively. The vertical contamination profile of DDTs was found in order of 20-30 cm >10-20 cm >0-10 cm, indicated that the residue levels of DDTs gradually decreased after it was banned. The ratios of β-HCH/HCHs ranged from 0.04 to 0.73 (69 % of samples below 0.5) suggesting the fresh input of HCHs, while isomeric ratios of α-HCH/γ-HCH (ranged from 0.02 to 7.94), with 76 % of samples less than 3, indicating the cocktail use of technical grade HCH and lindane in the study area. The r...
Nimesulide was formulated as novel dual coated microparticles using chitosan (CTN) and ethyl cell... more Nimesulide was formulated as novel dual coated microparticles using chitosan (CTN) and ethyl cellulose (EC) as encapsulating materials for its improved delivery to the intestine and to prevent gastric irritation and increase patient compliance. The first coating was applied by chitosan using pH change method followed by second coating of ethyl cellulose using thermal change method. This process was analysed for its capability to produce microparticles of uniform size, good flowability, uniform drug loading and maximum entrapment efficacy and the absence of interaction between drug and process parameters as well as the polymers confirmed by XRD and FTIR analysis. In vitro release study was carried out in simulated gastric fluid (SGF) for first 2 h and simulated intestinal fluid (SIF) for next 6 h. The formulation M7 and M8 that contained chitosan and ethyl cellulose in the concentration of 1:1 and 1:2 (M1:EC) were found to achieve the targets of the present study such as uniform intestinal release of acidic drug and thus improves the patient compliance.
Journal of the College of Physicians and Surgeons Pakistan Jcpsp, Sep 1, 2004
To determine association of hyperhomocysteinemia with myocardial infarction and conventional risk... more To determine association of hyperhomocysteinemia with myocardial infarction and conventional risk factors for ischemic heart disease.
The synthetic polymers and their combinations were employed to retard the release of nimesulide f... more The synthetic polymers and their combinations were employed to retard the release of nimesulide from microcapsules. Microcapsules were prepared in different ratios of Eudragit RL 100 and hydroxy propyl methyl cellulose (HPMC) separately and in combination. All formulations of microcapsules were compressed to tablets. Dissolution of microcapsules and their tablets was performed by USP-apparatus-II in 900 mL borate buffer of pH 8.4 at 37.0 ± 0.5 ºC, at 50 rpm. In vitro kinetics was determined by various models including Zero order, First Order, Higuchi, Korsmeyer-Peppas and Hixson-Crowell. Eudragit showed higher retarding effect over extended period of time on release of drug than HPMC alone or its combination with Eudragit.
Biodegradable microspheres of Tramadol Hydrochloride (TmH) were developed using simple phase sepa... more Biodegradable microspheres of Tramadol Hydrochloride (TmH) were developed using simple phase separation technique. Poly lactide-co-glycolide (PLGA) was employed as a release controlling polymer. Simple phase separation method was adopted to prepare microspheres; Dichloromethane (DCM) and Liquid Paraffin (LP) were employed as solvent and non-solvent respectively. Five kinetic models were applied to assess and describe the mechanism and pattern of TmH release from biodegradable microspheres. Biodegradable microspheres were subjected to FTIR, DSC and XRD, to evaluate TmH-PLGA interaction. Retardation in the release of TmH was observed as PLGA concentration was increased. Kinetics of drug release was following higuchi model. The microspheres exhibited no interaction between TmH and PLGA. Biodegradable microspheres of TmH can be produced using phase separation method. Microspheres were stable with no drug-polymer interaction. The accelerated stability studies also ensured the physicochemical integrity as differences of release profile over the period of three months were insignificant.
Many attempts have been done in the preparation of modified-release preparations of Tramadol Hydr... more Many attempts have been done in the preparation of modified-release preparations of Tramadol Hydrochloride (TH) to reduce the dose and the frequency of the dose during therapy. Trials on different polymeric systems are going on to get the required results. In present study ethyl cellulose (EC) and hydroxypropyl methylcellulose (HPMC) were used for the preparation of matrix tablets of tramadol hydrochloride. Six different formulations were prepared using different concentrations of these polymers. Effect of varying concentrations of EC and HPMC were observed on the modified release pattern of the matrices. Dissolution was performed in distilled water at 37.0 ± 0.5 ºC, while the stirring speed was set at 50 rpm. It was pragmatic that the formulations having low concentrations of either EC (25 or 50 mg) or HMPC (20 or 40 mg), more than 90 % drug was released during 12 hr. But when the concentrations of these polymers were increased less than 80 % of the drug was released from the matrix tablets during the said time (12 hr). The drug release behavior from formulations was evaluated using different kinetic models. It was obvious from these models that the most of the formulations followed the Higuchi square root model and the drug release mechanism was diffusion erosion. FDA similarity factor ƒ 2 was also calculated form which paramount difference was observed among the formulations.
Materials Science in Semiconductor Processing, 2017
A B S T R A C T Hybrid perovskite have shown a potential as structurally and chemically tunable m... more A B S T R A C T Hybrid perovskite have shown a potential as structurally and chemically tunable materials with interesting optical properties. Herein, We describe the synthesis and characterization of two new perovskites, hydroxyl ammonium lead iodo chloride, OHNH 3 PbI 2 Cl (1) and hydroxyl ammonium lead chloride, OHNH 3 PbCl 3 (2) by wet-chemical route. The as-prepared (1) and (2) have shown promising optical properties with suitable band gaps 3.7 eV and 3.9 eV respectvely. Time resolved Photoluminescence (PL) results showed that hybride pervoskite (2) had a long lived PL whereas (1) exhibited a short PL lifetime. Thermo-gravimetrical analysis (TGA) in nitrogen gas environment revealed that (1) and (2) are stable and do not show any sign of decomposition up to ~200 o C. Photocatalytical performance of as-prepared materials (1) and (2) under sunlight were mointerted using textile dye direct yellow. The compound (1) degraded dye in 20 min while (2) in 55 min with superior recyclablity.
In this study, matrix type patch formulations of flurbiprofen using certain skin permeation enhan... more In this study, matrix type patch formulations of flurbiprofen using certain skin permeation enhancers [isopropyl myristate (IPM), isopropyl palmitate (IPP) and Tween 80] were formulated, evaluated and compared. The cumulative amounts permeated and the permeation rates were higher for the prepared formulations as compared to the controls (without enhancers). The results also revealed better skin permeation characteristics of flurbiprofen using IPM than other enhancers. The pharmacokinetic parameters of the optimized formulation (F7), calculated from the blood levels of the drug, revealed a profile with the ability to maintain adequate plasma levels for 24 h (i.e. up to the next application): AUC (0-24) 10.406 ± 1.34ng.h/ml, T max 1.5 ± 0.91 and C max 1.3049 ± 0.21 μg.ml -1 . The amount of drug bioavailable for targeting the site of action is comparable to that of market control. Based on experimental results, preparation of 10 % flurbiprofen matrix type patch formulation containing IPM is promising.
Three derivatives of arylazapyrazole ((E)-4-(phenyldiazenyl)-3,5-dimethyl-1H-pyrazole, (E)-4-[(4-... more Three derivatives of arylazapyrazole ((E)-4-(phenyldiazenyl)-3,5-dimethyl-1H-pyrazole, (E)-4-[(4-flu-orophenyl)diazenyl]-3,5-dimethyl-1H-pyrazole, and (E)-4-[(4-iodophenyl)diazenyl]-3,5-dimethyl-1H-pyrazole) were synthesized, characterized, and further investigated for their electrochemical behavior at glassy carbon electrode using cyclic voltammetry. All compounds were reduced following E i C i mechanism giving single cathodic peak in potential range 0 to-2 V vs. Ag/AgCl. The plots of log i P vs. log m showed that the electrode process is mixed adsorption-diffusion controlled. The kinetic parameters such as transfer coefficient (an), diffusion coefficients (D o), and standard heterogeneous rate constants (k s) were determined from the electrochemical data. The values of D o were determined and found greater for the smallest among the three compounds. k s values were calculated by Laviron formalism which lies in the order of 10-2 s-1. Temperature and pH effects were studied and thermody-namic parameters such as change in free energy of activation (DG #), apparent activation energy (E a), enthalpy (DH #), and entropy (DS #) of activation were determined. Negative values of E a , DH # , and DS # imply that the electrode process needs lesser over potential with temperature rise, pre-adsorption of the analyte onto the electrode surface and the activated complex has a more organized structure than the reactants, respectively. Graphical abstract Keywords Arylazapyrazole Á Cyclic voltammetry Á Temperature and pH effect Á Kinetics Á Thermodynamics
The objective of this study was to formulate stable and controlled release microparticles for sim... more The objective of this study was to formulate stable and controlled release microparticles for simultaneous delivery and UV spectrophotometric detection in combined dosage of an non-steroidal anti-inflammatory drug (NSAID) (nimesulide, NMS) and a spasmolytic agent (tizanidine, TZN) to maintain plasma concentration that may increase patients compliance, improved therapeutic efficacy, The aim was also to reduce severity of upper GI side effects of NMS because of alteration in delivery pattern via slow release of drug from microparticles and to increase the benefits of spasticity and disability for spastic patients by administering TZN in a modified release formulation as these two drugs are often prescribed in combination for the management of pain associated with muscles spasm. Ethyl cellulose was used as a retardant polymer. Drug-polymer and drug-drug compatibility study were conducted by different analytical tests. Microparticles were prepared by coacervation thermal change method. The prepared microparticles were characterized for their micromeritics and drug loading. The prepared microparticles were light yellow, free flowing and spherical in shape. The drug-loaded microparticles showed 87% and 91% entrapment efficiency of NMS and TZN, respectively, and release was extended up to 10 h. The infrared spectra, differential scanning calorimetry thermograms and XRD spectra showed the stable character of both the drugs in the drug-loaded microparticles. The in vitro release study of microparticles was performed in phosphate buffer pH 6.8. Linearity was observed in the concentration range of 5.0-30.0 microg/mL of NMS and 0.5-3.0 microg/mL of TZN. The microparticles have a potential for the prolongation and simultaneous delivery of the NIM and TIZ. The proposed UV method for simultaneous detection can be used for routine analysis of combined dosage form.
Journal of the College of Physicians and Surgeons Pakistan Jcpsp, Mar 1, 2004
OBJECTIVE: To evaluate the risk of malignancy index (RMI) for pre-operative diagnosis of ovarian ... more OBJECTIVE: To evaluate the risk of malignancy index (RMI) for pre-operative diagnosis of ovarian mass.DESIGN: Observational study.PLACE AND DURATION OF STUDY: Department of Chemical Pathology and Endocrinology at Armed Forces Institute of Pathology (AFIP), Rawalpindi from January 2001 to January 2002.SUBJECTS AND METHODS: The study consisted of 100 female patients consecutively admitted for surgical exploration of ovarian mass. Pre-operatively ultrasonic evaluation of ovarian mass, menopausal status and serum cancer-associated antigen 125 (CA 125) levels were carried out. Postoperatively histopathology of the resected ovarian mass was done to confirm the diagnosis. To increase the sensitivity and specificity of CA 125 for early detection of ovarian cancer, a combination of serum CA 125 with ultrasonography and menopausal status, designated as risk of malignancy index (RMI) for each patient, was calculated.RESULTS: The sensitivity and specificity of CA 125 alone for the diagnosis of ovarian cancer, at cutoff level of 35 U/ml, were 83% and 82% respectively. Using RMI, at cutoff level of 125, the sensitivity was 87%, and specificity was 88%. Receiver operating characteristic (ROC) curves reveal that RMI was a better discriminant than CA 125 alone for differentiating between benign lesions and malignant ovarian tumors.CONCLUSION: The risk of malignancy index (RMI) is a better diagnostic marker as compared to CA 125 alone because of its high specificity and sensitivity in differentiating ovarian cancer from ovarian benign lesions. It is a simple scoring system and, therefore, its application is recommended to evaluate ovarian masses in clinical practice.
Environmental science and pollution research international, Jan 14, 2016
This study aimed to investigate the potential health risk associated with toxic metals in contami... more This study aimed to investigate the potential health risk associated with toxic metals in contaminated foodstuffs (fruits, vegetables, and cereals) collected from various agriculture fields present in chromite mining-affected areas of mafic and ultramafic terrains (northern Pakistan). The concentrations of Cr, Ni, Zn, Cd, and Pb were quantified in both soil and food samples. The soil samples were highly contaminated with Cr (320 mg/kg), Ni (108 mg/kg), and Cd (2.55 mg/kg), which exceeded their respective safe limits set by FAO/WHO. Heavy metal concentrations in soil were found in the order of…
Mixed metal halide perovskites are gaining paramount interest due to efficient band gap tenabilit... more Mixed metal halide perovskites are gaining paramount interest due to efficient band gap tenability and improved optical properties compared to their single metal halide perovskites. It is thus valuable to investigate compositional changes in lead halide perovskites to explore energy changes. Herein, we report the synthesis of a lead to lead free hybrid perovskite solid solution (CH 3 NH 3 Pb 1Àx Cu x Br 3) as nanoparticles and films. The increasing concentration of Cu 2+ ions in the site of the Pb 2+ ion in the perovskite shifted the diffraction peaks to a larger angle. Uniform spherically shaped nanoparticles were synthesized by a wet chemical method, the higher Cu 2+ concentration leads to agglomeration, producing sheet like morphologies. However, the deposition of thin films of CH 3 NH 3 Pb 1Àx Cu x Br 3 perovskite solid solution shows that well defined morphologies begin to appear with increasing concentrations of Cu 2+ in the perovskite structure. The as-prepared bulk lead free CH 3 NH 3 CuBr 3 perovskite shows a band gap of 1.65 eV. A blue shift in photoluminescence (PL) was observed with copper enriched hybrid perovskites.
Inorganic halide perovskite (CsPbX 3) nanostructures have gained considerable interest in recent ... more Inorganic halide perovskite (CsPbX 3) nanostructures have gained considerable interest in recent years owing to their enhanced stability and optoelectronic applications. Recent developments in the synthesis of nanostructures are reviewed. The impact of the precursor and ligand nature, temperature and growth time on the morphology and shape tuning of CsPbX 3 nanostructures is described in relation to their optical properties. The presynthetic and postsynthetic anion exchange strategies to retain pre-existing crystal phase and shape are discussed in this minireview.
The present study was undertaken to evaluate the effect of glyceryl monostearate (GMS) and steari... more The present study was undertaken to evaluate the effect of glyceryl monostearate (GMS) and stearic acid (SA) on the release profile of gliclazide from the matrix. Matrix tablets for the controlled delivery of gliclazide were prepared by hot melt method using pure and blended mixture of glyceryl monostearate and stearic acid in different drug to polymer and polymer to polymer ratios. In vitro release characteristics of gliclazide from these hydrophobic matrices were studied over 8 h in phosphate buffer media of pH 7.4. The release kinetics of drug was evaluated for zero order, first order, Higuchi and Peppas kinetic models. It was observed that the release of drug from the matrix was greatly retarded by GMS and retarding effect increased with increasing polymer to drug ratios. On the other hand SA appeared to channel the drug from the wax matrix and release was greatly increased with increasing polymer to drug ratios. The kinetic evaluation of release profile indicated that the Higuchi model was the most appropriate model for describing the release profile of gliclazide. The application of Peppas biexponential equation indicated that non-Fickian release was the predominant mechanism of drug release. The FTIR results showed no interaction between the drug and the polymers and DSC results indicated that both the drug and polymers are in amorphous state and no significant complexes were formed. The results indicated that proper selection of drug to polymer and polymer to polymer ratios were important in order to achieve the desired dissolution profile in these matrix tablets.
The aim of this study was to formulate ethyl cellulose (EC) microparticles for sustained release ... more The aim of this study was to formulate ethyl cellulose (EC) microparticles for sustained release of nimesulide and study the effect of processing variables, drug to polymer ratio and also study the drug polymer compatibility. The microparticles were prepared by coacervation (temperature change) technique. Physical properties, such as particle size, entrapment efficiency, release pattern and morphological characteristics were investigated by in vitro dissolution, SEM, FTIR, XRD, DSC and TGA in order to optimize the formulation of the microparticles. With the increase of polymer concentration there was an increase in size and drug entrapment efficiency of microparticles. There was a decrease in size and nonlinear change in entrapment efficiency with the increase of stirring speed and time. The release of drug from microparticles was anomalous diffusion. It was confirmed that there is no strong chemical interaction between drug and polymer except the change in crystal habit and polymorphism. Ethyl cellulose microparticles containing nimesulide are suitable for controlled release devising.
N ew formulations of microparticles for Tramadol HCl (TmH) controlled-release were developed and ... more N ew formulations of microparticles for Tramadol HCl (TmH) controlled-release were developed and evaluated. These microparticles with controlled-release characteristics were prepared by non-solvent addition technique. Ethyl cellulose (EC) a hydrophobic polymer was employed to control and extend the drug release process. Dichloromethane (DCM) was employed as solvent for polymer and paraffin oil as non-solvent which induced phase separation. Microparticles of different polymer concentrations M 1 (1:1), M 2 (1:2) and M 3 (1:3) were prepared. Among all these formulations, M 3 presented superior and desirable characteristics, i.e., 79% entrapment efficiency, good micromeritic properties, smooth morphology, and more sustained effect on cumulative release. Zero order, first order, Higuchi, Hixson-Crowell, and Korsmeyer-Peppas kinetic models were applied to assess the mechanism and pattern of drug release from microparticles. Release of TmH was best fitted to Higuchi model because it presented highest values of correlation coefficient (R 2 = 0.981) followed by zero-order kinetic model (R 2 = 0.899). FTIR, XRD, and DSC analyses ensured the chemical stability and integrity of TmH and EC in M 3 as no new bands were detected in FTIR spectra. Moreover the XRD patterns of TmH showed its reduced crystallinity and endothermic peak was observed at the glass transition temperature of EC in DSC spectra. M 3 sample was kept at 40ºC/75% RH for three months and its stability was evaluated by determining sample's in vitro release profile and drug assay.
African Journal of Pharmacy and Pharmacology, Oct 22, 2011
The purpose of this study was to assess bioequivalence of two marketed formulations of celecoxib ... more The purpose of this study was to assess bioequivalence of two marketed formulations of celecoxib capsules in healthy human male volunteers. The study was conducted according to a single dose, randomized sequence, open label, two-period and crossover design. Both test and reference formulations comprised labeled dose of 200 mg celecoxib and were administered to each subject after an overnight fasting on two treatment days separated by one week of washout period. After drug administration, blood samples were collected at predetermined time points for a period of 48 h. Plasma separated from blood was analyzed for celecoxib concentrations using validated reverse phase-high performance liquid chromatographic (RP-HPLC) method. Various pharmacokinetic parameters including C max , T max , AUC 0-t , AUC 0-∞ , T 1/2 and K el were determined from the plasma concentration for both formulations. C max , AUC 0-t and AUC 0-∞ , were evaluated for bioequivalence after log-transformation of data. The 90% confidence intervals for the ratio of C max (93.26 to 100.70%), AUC 0-t (87.00 to 117.50%) and AUC 0-∞ (86.49 to 118.56%), values for the test and reference products were within the acceptance range of 80 to 125%, proposed by Food and Drug Administration (FDA) and European Medicines Evaluation Agency (EMEA). Based on these statistical inferences, it was concluded that two formulations of celecoxib are bioequivalent in their rate and extent of absorption.
Environmental geochemistry and health, Jan 29, 2016
Hexachlorocyclohexane (HCH) isomers and dichlorodiphenyltrichloroethane (DDT) metabolites were an... more Hexachlorocyclohexane (HCH) isomers and dichlorodiphenyltrichloroethane (DDT) metabolites were analyzed in sediments of three different depths (0-10, 10-20 and 20-30 cm) collected from Kabul River, Pakistan, in February 2014. The occurrence levels, enantiomer fractions and potential ecological risk of these organochlorine pesticides (OCPs) were evaluated. The total concentrations of ∑HCHs and ∑DDTs in surface sediments ranged from 4.9-23.9 ng g(-1) and from 6.4-18.8 ng g(-1) (dry weight basis), respectively. The vertical contamination profile of DDTs was found in order of 20-30 cm >10-20 cm >0-10 cm, indicated that the residue levels of DDTs gradually decreased after it was banned. The ratios of β-HCH/HCHs ranged from 0.04 to 0.73 (69 % of samples below 0.5) suggesting the fresh input of HCHs, while isomeric ratios of α-HCH/γ-HCH (ranged from 0.02 to 7.94), with 76 % of samples less than 3, indicating the cocktail use of technical grade HCH and lindane in the study area. The r...
Nimesulide was formulated as novel dual coated microparticles using chitosan (CTN) and ethyl cell... more Nimesulide was formulated as novel dual coated microparticles using chitosan (CTN) and ethyl cellulose (EC) as encapsulating materials for its improved delivery to the intestine and to prevent gastric irritation and increase patient compliance. The first coating was applied by chitosan using pH change method followed by second coating of ethyl cellulose using thermal change method. This process was analysed for its capability to produce microparticles of uniform size, good flowability, uniform drug loading and maximum entrapment efficacy and the absence of interaction between drug and process parameters as well as the polymers confirmed by XRD and FTIR analysis. In vitro release study was carried out in simulated gastric fluid (SGF) for first 2 h and simulated intestinal fluid (SIF) for next 6 h. The formulation M7 and M8 that contained chitosan and ethyl cellulose in the concentration of 1:1 and 1:2 (M1:EC) were found to achieve the targets of the present study such as uniform intestinal release of acidic drug and thus improves the patient compliance.
Journal of the College of Physicians and Surgeons Pakistan Jcpsp, Sep 1, 2004
To determine association of hyperhomocysteinemia with myocardial infarction and conventional risk... more To determine association of hyperhomocysteinemia with myocardial infarction and conventional risk factors for ischemic heart disease.
The synthetic polymers and their combinations were employed to retard the release of nimesulide f... more The synthetic polymers and their combinations were employed to retard the release of nimesulide from microcapsules. Microcapsules were prepared in different ratios of Eudragit RL 100 and hydroxy propyl methyl cellulose (HPMC) separately and in combination. All formulations of microcapsules were compressed to tablets. Dissolution of microcapsules and their tablets was performed by USP-apparatus-II in 900 mL borate buffer of pH 8.4 at 37.0 ± 0.5 ºC, at 50 rpm. In vitro kinetics was determined by various models including Zero order, First Order, Higuchi, Korsmeyer-Peppas and Hixson-Crowell. Eudragit showed higher retarding effect over extended period of time on release of drug than HPMC alone or its combination with Eudragit.
Biodegradable microspheres of Tramadol Hydrochloride (TmH) were developed using simple phase sepa... more Biodegradable microspheres of Tramadol Hydrochloride (TmH) were developed using simple phase separation technique. Poly lactide-co-glycolide (PLGA) was employed as a release controlling polymer. Simple phase separation method was adopted to prepare microspheres; Dichloromethane (DCM) and Liquid Paraffin (LP) were employed as solvent and non-solvent respectively. Five kinetic models were applied to assess and describe the mechanism and pattern of TmH release from biodegradable microspheres. Biodegradable microspheres were subjected to FTIR, DSC and XRD, to evaluate TmH-PLGA interaction. Retardation in the release of TmH was observed as PLGA concentration was increased. Kinetics of drug release was following higuchi model. The microspheres exhibited no interaction between TmH and PLGA. Biodegradable microspheres of TmH can be produced using phase separation method. Microspheres were stable with no drug-polymer interaction. The accelerated stability studies also ensured the physicochemical integrity as differences of release profile over the period of three months were insignificant.
Many attempts have been done in the preparation of modified-release preparations of Tramadol Hydr... more Many attempts have been done in the preparation of modified-release preparations of Tramadol Hydrochloride (TH) to reduce the dose and the frequency of the dose during therapy. Trials on different polymeric systems are going on to get the required results. In present study ethyl cellulose (EC) and hydroxypropyl methylcellulose (HPMC) were used for the preparation of matrix tablets of tramadol hydrochloride. Six different formulations were prepared using different concentrations of these polymers. Effect of varying concentrations of EC and HPMC were observed on the modified release pattern of the matrices. Dissolution was performed in distilled water at 37.0 ± 0.5 ºC, while the stirring speed was set at 50 rpm. It was pragmatic that the formulations having low concentrations of either EC (25 or 50 mg) or HMPC (20 or 40 mg), more than 90 % drug was released during 12 hr. But when the concentrations of these polymers were increased less than 80 % of the drug was released from the matrix tablets during the said time (12 hr). The drug release behavior from formulations was evaluated using different kinetic models. It was obvious from these models that the most of the formulations followed the Higuchi square root model and the drug release mechanism was diffusion erosion. FDA similarity factor ƒ 2 was also calculated form which paramount difference was observed among the formulations.
Materials Science in Semiconductor Processing, 2017
A B S T R A C T Hybrid perovskite have shown a potential as structurally and chemically tunable m... more A B S T R A C T Hybrid perovskite have shown a potential as structurally and chemically tunable materials with interesting optical properties. Herein, We describe the synthesis and characterization of two new perovskites, hydroxyl ammonium lead iodo chloride, OHNH 3 PbI 2 Cl (1) and hydroxyl ammonium lead chloride, OHNH 3 PbCl 3 (2) by wet-chemical route. The as-prepared (1) and (2) have shown promising optical properties with suitable band gaps 3.7 eV and 3.9 eV respectvely. Time resolved Photoluminescence (PL) results showed that hybride pervoskite (2) had a long lived PL whereas (1) exhibited a short PL lifetime. Thermo-gravimetrical analysis (TGA) in nitrogen gas environment revealed that (1) and (2) are stable and do not show any sign of decomposition up to ~200 o C. Photocatalytical performance of as-prepared materials (1) and (2) under sunlight were mointerted using textile dye direct yellow. The compound (1) degraded dye in 20 min while (2) in 55 min with superior recyclablity.
In this study, matrix type patch formulations of flurbiprofen using certain skin permeation enhan... more In this study, matrix type patch formulations of flurbiprofen using certain skin permeation enhancers [isopropyl myristate (IPM), isopropyl palmitate (IPP) and Tween 80] were formulated, evaluated and compared. The cumulative amounts permeated and the permeation rates were higher for the prepared formulations as compared to the controls (without enhancers). The results also revealed better skin permeation characteristics of flurbiprofen using IPM than other enhancers. The pharmacokinetic parameters of the optimized formulation (F7), calculated from the blood levels of the drug, revealed a profile with the ability to maintain adequate plasma levels for 24 h (i.e. up to the next application): AUC (0-24) 10.406 ± 1.34ng.h/ml, T max 1.5 ± 0.91 and C max 1.3049 ± 0.21 μg.ml -1 . The amount of drug bioavailable for targeting the site of action is comparable to that of market control. Based on experimental results, preparation of 10 % flurbiprofen matrix type patch formulation containing IPM is promising.
Three derivatives of arylazapyrazole ((E)-4-(phenyldiazenyl)-3,5-dimethyl-1H-pyrazole, (E)-4-[(4-... more Three derivatives of arylazapyrazole ((E)-4-(phenyldiazenyl)-3,5-dimethyl-1H-pyrazole, (E)-4-[(4-flu-orophenyl)diazenyl]-3,5-dimethyl-1H-pyrazole, and (E)-4-[(4-iodophenyl)diazenyl]-3,5-dimethyl-1H-pyrazole) were synthesized, characterized, and further investigated for their electrochemical behavior at glassy carbon electrode using cyclic voltammetry. All compounds were reduced following E i C i mechanism giving single cathodic peak in potential range 0 to-2 V vs. Ag/AgCl. The plots of log i P vs. log m showed that the electrode process is mixed adsorption-diffusion controlled. The kinetic parameters such as transfer coefficient (an), diffusion coefficients (D o), and standard heterogeneous rate constants (k s) were determined from the electrochemical data. The values of D o were determined and found greater for the smallest among the three compounds. k s values were calculated by Laviron formalism which lies in the order of 10-2 s-1. Temperature and pH effects were studied and thermody-namic parameters such as change in free energy of activation (DG #), apparent activation energy (E a), enthalpy (DH #), and entropy (DS #) of activation were determined. Negative values of E a , DH # , and DS # imply that the electrode process needs lesser over potential with temperature rise, pre-adsorption of the analyte onto the electrode surface and the activated complex has a more organized structure than the reactants, respectively. Graphical abstract Keywords Arylazapyrazole Á Cyclic voltammetry Á Temperature and pH effect Á Kinetics Á Thermodynamics
The objective of this study was to formulate stable and controlled release microparticles for sim... more The objective of this study was to formulate stable and controlled release microparticles for simultaneous delivery and UV spectrophotometric detection in combined dosage of an non-steroidal anti-inflammatory drug (NSAID) (nimesulide, NMS) and a spasmolytic agent (tizanidine, TZN) to maintain plasma concentration that may increase patients compliance, improved therapeutic efficacy, The aim was also to reduce severity of upper GI side effects of NMS because of alteration in delivery pattern via slow release of drug from microparticles and to increase the benefits of spasticity and disability for spastic patients by administering TZN in a modified release formulation as these two drugs are often prescribed in combination for the management of pain associated with muscles spasm. Ethyl cellulose was used as a retardant polymer. Drug-polymer and drug-drug compatibility study were conducted by different analytical tests. Microparticles were prepared by coacervation thermal change method. The prepared microparticles were characterized for their micromeritics and drug loading. The prepared microparticles were light yellow, free flowing and spherical in shape. The drug-loaded microparticles showed 87% and 91% entrapment efficiency of NMS and TZN, respectively, and release was extended up to 10 h. The infrared spectra, differential scanning calorimetry thermograms and XRD spectra showed the stable character of both the drugs in the drug-loaded microparticles. The in vitro release study of microparticles was performed in phosphate buffer pH 6.8. Linearity was observed in the concentration range of 5.0-30.0 microg/mL of NMS and 0.5-3.0 microg/mL of TZN. The microparticles have a potential for the prolongation and simultaneous delivery of the NIM and TIZ. The proposed UV method for simultaneous detection can be used for routine analysis of combined dosage form.
Journal of the College of Physicians and Surgeons Pakistan Jcpsp, Mar 1, 2004
OBJECTIVE: To evaluate the risk of malignancy index (RMI) for pre-operative diagnosis of ovarian ... more OBJECTIVE: To evaluate the risk of malignancy index (RMI) for pre-operative diagnosis of ovarian mass.DESIGN: Observational study.PLACE AND DURATION OF STUDY: Department of Chemical Pathology and Endocrinology at Armed Forces Institute of Pathology (AFIP), Rawalpindi from January 2001 to January 2002.SUBJECTS AND METHODS: The study consisted of 100 female patients consecutively admitted for surgical exploration of ovarian mass. Pre-operatively ultrasonic evaluation of ovarian mass, menopausal status and serum cancer-associated antigen 125 (CA 125) levels were carried out. Postoperatively histopathology of the resected ovarian mass was done to confirm the diagnosis. To increase the sensitivity and specificity of CA 125 for early detection of ovarian cancer, a combination of serum CA 125 with ultrasonography and menopausal status, designated as risk of malignancy index (RMI) for each patient, was calculated.RESULTS: The sensitivity and specificity of CA 125 alone for the diagnosis of ovarian cancer, at cutoff level of 35 U/ml, were 83% and 82% respectively. Using RMI, at cutoff level of 125, the sensitivity was 87%, and specificity was 88%. Receiver operating characteristic (ROC) curves reveal that RMI was a better discriminant than CA 125 alone for differentiating between benign lesions and malignant ovarian tumors.CONCLUSION: The risk of malignancy index (RMI) is a better diagnostic marker as compared to CA 125 alone because of its high specificity and sensitivity in differentiating ovarian cancer from ovarian benign lesions. It is a simple scoring system and, therefore, its application is recommended to evaluate ovarian masses in clinical practice.
Environmental science and pollution research international, Jan 14, 2016
This study aimed to investigate the potential health risk associated with toxic metals in contami... more This study aimed to investigate the potential health risk associated with toxic metals in contaminated foodstuffs (fruits, vegetables, and cereals) collected from various agriculture fields present in chromite mining-affected areas of mafic and ultramafic terrains (northern Pakistan). The concentrations of Cr, Ni, Zn, Cd, and Pb were quantified in both soil and food samples. The soil samples were highly contaminated with Cr (320 mg/kg), Ni (108 mg/kg), and Cd (2.55 mg/kg), which exceeded their respective safe limits set by FAO/WHO. Heavy metal concentrations in soil were found in the order of…
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Papers by Muhammad Aamir