Jamshaid Ali Khan

A new HPLC method for the simultaneous determination of ascorbic acid and aminothiols in human plasma and erythrocytes using electrochemical detection

A new, simple, economical and validated high-performance liquid chromatography linked with electrochemical detector (HPLC-ECD) method has been developed and optimized for different experimental parameters to analyze the most common monothiols and disulfide (cystine, cysteine, homocysteine, methionine, reduced (GSH) and oxidized glutathione (GSSG)) and ascorbic acid present in human plasma and erythrocytes using dopamine as internal standard (IS). Complete separation of all the targets analytes and IS at 35°C on Discovery HS C18 RP column (250 mm × 4.6mm, 5 μm) was achieved using 0.05% TFA:methanol (97:3, v/v) as a mobile phase pumped at the rate of 0.6 ml min(-1) using electrochemical detector in DC mode at the detector potential of 900 mV. The limits of detection (3 S/N) and limits of quantification (10 S/N) of the studied compounds were evaluated using dilution method. The proposed method was validated according to standard guidelines and optimization of various experimental parameters and chromatographic conditions was carried out. The optimized and validated HPLC-ECD method was successfully applied for the determination of the abovementioned compounds in human plasma and erythrocytes. The method will be quite suitable for the determination of plasma and erythrocyte profile of ascorbic acid and aminothiols in oxidative stress and other basic research studies.

Simultaneous determination of timolol maleate, rosuvastatin calcium and diclofenac sodium in pharmaceuticals and physiological fluids using HPLC-UV.

A novel HPLC-UV method was developed for the simultaneous determination of timolol (TM), rosuvastatin (RST), and diclofenac sodium (DS) in pharmaceuticals, human plasma and aqueous humor using naproxen sodium as internal standard (IS). The target compounds were analyzed on Hypersil BDS C(18) column (250 mm × 4.6 mm, 5 μm), applying 0.2% triethylamine (TEA) and acetonitrile (ACN) (40:60, v/v), in isocratic mode as mobile phase, pH 2.75 adjusted with 85% phosphoric acid at a flow rate of 1 ml/min. The column oven temperature was kept at 45°C and the peak response was monitored at 284 nm after injecting a 50 μl sample into HPLC system. The direct liquid-liquid extraction procedure was applied to human plasma and bovine aqueous humor samples using mobile phase as an extraction solvent after deproteination with methanol. The different HPLC experimental parameters were optimized and the method was validated according to standard guidelines. The recoveries of the suggested method in human plasma were 98.72, 96.04, and 95.14%, for TM, RST, and DS, while in aqueous humor were 94.99, and 98.23%, for TM, and DS, respectively. The LOD values were found to be 0.800, 0.500, and 0.250 ng/ml, for TM, RST, and DS, respectively, while their respective LOQ values were 2.00, 1.50, and 1.00 ng/ml. The co-efficient of variation (CV) were in the range of 0.1492-1.1729% and 1.0516-4.0104%, for intra-day and inter-day studies, respectively. The method was found accurate in human plasma and bovine aqueous humor and will be applied for the quantification of these compounds in plasma, and aqueous humor samples using animal models and in pharmaceuticals.

Development and evaluation of diclofenac sodium thermorevesible subcutaneous drug delivery system

The objective of current work was to develop and evaluate thermoreversible subcutaneous drug delivery system for diclofenac sodium. The poloxamer 407, methyl cellulose, hydroxypropyl methyl cellulose and polyethylene glycol were used alone and in combination in different ratios to design the delivery system. The physical properties like Tsol-gel, viscosity, clarity of solution and gel were evaluated. The in vitro release of the drug delivery system was evaluated using membrane less method and the drug release kinetics and mechanism was predicted by applying various mathematical models to the in vitro dissolution data. Rabbits were used as in vivo model following subcutaneous injection to predict various pharmacokinetics parameters by applying Pk-Summit software. The in vitro and in vivo data revealed that the system consisting of the poloxamer 407 in concentration of 20% (DP20) was the most capable formulation for extending the drug release and maintaining therapeutic blood level of DS for longer duration (144 h). The data obtained for drug content after autoclaving the solutions indicate that autoclaving results in 6% degradation of DS. The data also suggested that the studied polymers poloxamer, MC and PG are good candidate to extend the drug release possessing a unique thermoreversible property.

Pharmacokinetic interaction of ciprofloxacin with diclofenac: a single-dose, two-period crossover study in healthy adult volunteers.

AbstractBackground and objective: Ciprofloxacin is a broad-spectrum, synthetic antibacterial used for the treatment of various bacterial infections. In multidrug therapy, ciprofloxacin is commonly prescribed with analgesics for the management of infection, pain and inflammation. The objective of this study was to evaluate the pharmacokinetic properties of ciprofloxacin tablets with concurrent administration of diclofenac tablets in healthy adult human volunteers. Methods and design: The disposition pharmacokinetics of a single oral dose of ciprofloxacin 500 mg alone and with co-administration of a diclofenac 50 mg tablet in 12 healthy male volunteers was investigated using a two-period, crossover design. The blood samples were collected at 0 (predose), 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16 and 24 hours after administration of the drugs and the concentration of ciprofloxacin in serum was determined using reversed phase high-performance liquid chromatography. The pharmacokinetic parameters were calculated using a noncompartmental model and a two-compartment model. Results: The maximum plasma concentration (Cmax) of ciprofloxacin increased from 2.48±0.33 mg/mL when administered alone to 3.91±0.8 mg/mL with co-administration of diclofenac. Time to reach Cmax (tmax) with ciprofloxacin reduced from 2.02±0.3 hours when administered alone to 1.49±0.2 h with co-administration of diclofenac. Significant increases in ciprofloxacin area under the serum concentration-time curve (AUC) and elimination half-life, together with a significant decrease in total body clearance of ciprofloxacin, were observed with concurrent administration of diclofenac. Conclusion: Oral co-administration of ciprofloxacin tablets with diclofenac tablets increased ciprofloxacin AUC and Cmax, and reduced ciprofloxacin tmax and total body clearance.

Development and evaluation of pluronic- and methylcellulose-based thermoreversible drug delivery system for insulin

Abstract The objective of the current work was to develop and evaluate thermoreversible subcutaneous drug delivery system for Insulin. Thermoreversible in-situ gel system was developed and evaluated both in-vitro and in-vivo comprising of pluronic F-127 alone or in combination with methylcellulose in different ratios. The drug release kinetics and mechanism was predicted by applying various mathematical models to the in-vitro dissolution data. Rabbits were used as animal model following subcutaneous injection to predict various pharmacokinetic parameters by applying Pk-Summit® software. The in-vitro and in-vivo data revealed that the formulation IPM 15/3 consisting of the pluronic F-127 (15% w/v) and methylcellulose (3% w/v) was the most robust and capable formulation for extending the drug release and maintaining basal plasma insulin level between 10 and 40 µU/ml for 240 h (10 d).

Oral dispersible system: A new approach in drug delivery system

Dosage form is a mean used for the delivery of drug to a living body. In order to get the desired effect the drug should be delivered to its site of action at such rate and concentration to achieve the maximum therapeutic effect and minimum adverse effect. Since oral route is still widely accepted route but having a common drawback of difficulty in swallowing of tablets and capsules. Therefore a lot of research has been done on novel drug delivery systems. This review is about oral dispersible tablets a novel approach in drug delivery systems that are now a days more focused in formulation world, and laid a new path that, helped the patients to build their compliance level with the therapy, also reduced the cost and ease the administration especially in case of pediatrics and geriatrics. Quick absorption, rapid onset of action and reduction in drug loss properties are the basic advantages of this dosage form.

Simultaneous Determination of Endogenous Antioxidants and Malondialdehyde by RP-HPLC Coupled with Electrochemical Detector in Serum Samples

A new method has been developed and validated based on high-performance liquid chromatography for simultaneous determination of endogenous aminothiols (cystine, cysteine, homocystiene, methionine, reduced and oxidized glutathione, N-acetylcysteine), ascorbic acid, and malondialdehyde in single elution using electrochemical detector kept at 900 mV electrode potential on Discovery 250 mm C18 RP chromatographic column. The elution time was 20 min, using flow rate of 0.6 mL/min, injecting 5 µL sample for analysis after extraction. The method was validated according to standard guidelines for accuracy, linearity, specificity, reproducibility, limit of detection and limit of quantification and was successfully applied to serum samples of healthy animal model. The analytes were determined using dilution method and values were calculated in mmol/L. This method can be applied to clinical pathologies related to oxidative stress and metabolic syndromes for assessment of severity and facilitate in developing a correlation between the endogenous antioxidant capacities with exogenous antioxidant interventions.

Pharmacokinetic Profiling of a Novel Flavonoid “Viscosine” from Dodonaea viscosa Using High Performance Liquid Chromatography

Pharmacokinetic (PK) profiling of a novel flavonoid “Viscosine” was carried out in healthy rabbits following both IV and oral administration. Various PK parameters were investigated using the developed HPLC–UV method. The concentration of the Viscosine in plasma samples following both IV and oral administration was plotted as a function of time on normal and semi-log graph papers. The plasma drug concentration as a function of time profile of the Viscosine following IV bolus administration and oral administration showed the bi-exponential decline that indicates that PK of the Viscosine follows two compartment open model. The Viscosine is rapidly but incompletely absorbed following oral administration from hard gelatin capsules and tmax was achieved just in 0.5 hr (30 min). The mean ± SD of Cmax was 0.981 ± 0.021 µg/mL. The very low plasma drug concentration achieved shows that Viscosine has lower permeability following oral administration. Similarly, following IV bolus drug administration, the plasma drug concentration as a function of time curve of Viscosine was a bi-exponential curve that follows two compartment open model. Viscosine is readily distributed and established equilibrium between central and peripheral compartments. Higher volume of distribution (Vd) shows the longer stay in the peripheral compartments. The β-elimination half-life is approximately 3.8 hr. The AUC values also indicate the distribution of the drug in various body fluids. In summary, the bioavailability of the drug after oral administration (F = 0.32) indicates that Viscosine is a low soluble drug; however, the Vd was higher compared with the IV bolus injection while MRT was about 15.45 hr. These studies indicate that capsules can be used as a suitable dosage form for the administration of Viscosine.

EVALUATION OF COMMONLY USED PRESERVATIVES IN VARIOUS ANALGESIC SUSPENSIONS THROUGH HPLC AND MICROBIAL ASSAY

Stability of pharmaceutical products is the ultimate objective of the pharmaceutical sector. Preservatives are the essential and effective part of all types of Syrup and suspension formulations. A fast reversed-phase high performance liquid chromatography method is developed for the determination of sodium benzoate (SB) and alkyl esters of Para hydroxyl benzoic acid such as ethyl paraben (EP), methyl paraben (MP), and propyl paraben (PP) in marketed analgesic suspensions collected from different sources. Complete separation of all the analytes was achieved on an Hypercil C18 (256 mm × 6.4 mm; 5 µm) column using acetonitrile and acetate buffer (pH 5) in the ratio of (35:65, v/v) as the mobile phase pumped at a flow rate of 1.5 mL/min in isocratic mode. Under the optimized experiment conditions, separation of the analytes was achieved in less the 10 min. Efficacy of the preservatives is determined in the prepared suspensions using the identified strains of bacteria, that is, Escherichia coli ATCC (8739), Pseudomonas aeruginosa ATCC (9027), and Staphylococcus aureus ATCC (6538) for a period of 28 d.

A multicentered pharmacoepidemiological approach to evaluate clinically significant potential drug–drug interactions in medical intensive care settings in Pakistan

Background: Iatrogenic injuries due to drug–drug interactions are particularly significant in critical care units because of the severely compromised state of the patient. The risk further increases with the use of multiple drugs, increasing age, and stay of the patient. Objective: The aim was to assess potential drug–drug interactions, evaluate clinically significant potential drug–drug interactions and their predictors in medical intensive care units of tertiary hospitals in Pakistan. Methods: Analysis of patient data collected from medical intensive care units of tertiary hospitals in Pakistan were carried out using Micromedex DrugReax. Various statistical tools were applied to identify the significance of associated predictors. Results: In a total of 830 patients, prevalence of potential drug–drug interactions was found to be 39%. These attributed to 190 drug combinations, of which 15.4% were clinically significant. A significant association of potential drug–drug interactions was present with number of prescribed drugs, age, and gender. In terms of clinically significant potential drug–drug interactions, the association was significant with increasing age. Moreover, one-way analysis of variance revealed a significant difference in the means of potential drug–drug interactions among the four hospitals. Conclusion: A prevalence of 39% potential drug–drug interactions was observed in patients of medical intensive care unit, with 22.8% being clinically significant. These attributed to nine drug pairs and could easily be avoided to reduce the risk of adverse effects from potential drug–drug interactions.