Current Pharmaceutical Analysis - Volume 10, Issue 4, 2014

Caffeine is the oldest consumed psychoactive drug, present in coffee, cocoa, tea, among other products. Several conventional methods are used to analyze caffeine, for example, chromatography and spectrometry, but these methods are expensive when compared to electroanalytical methods. The objective of this study is to study the feasible applicability of electrochemical techniques for quantification of caffeine in medications. Cyclic voltammetry was performed on the platinum electrode in 0.5 M H2SO4 and after that differential pulse voltammetry was performed to obtain the linear relation between caffeine concentration and current. A linear response in the electroanalytical approach exists from 38.05±3.02 to 192.39±1.04 ppm with a limit of detection of about 9.09±0.72 ppm. This sensor may represent a new analytical tool for caffeine analysis, based on existing literature.

We developed a method that uses flow through voltammetric sensor to quantitatively determine thiazolidine-2, 4-diones (TZDs) derivatives which are pioglitazone, rosiglitazone and troglitazone. The method uses a gold electrode. The dynamic range for determining thiazolidine-2, 4-diones (TZDs) is extended by more than two orders of magnitude. The quantification limits are 0.10, 23, 15, 0.005 ng for thiazolidine-2, 4-dione, pioglitazone, rosiglitazone and troglitazone, respectively. The method can be applied to the quantitatively determining pioglitazone and rosiglitazone in antidiabetic drugs. Findings using high-performance liquid chromatography with a flow-through voltammetric detector and ultraviolet detector are comparable.

We have developed an efficient method for fast determination and pharmacokinetic study of paclitaxel in rat plasma. The method involved a flow-injection chemiluminescence (FI-CL) technique that depends on the inhibition of a luminol/ sulfobutylether-β-cyclodextrin (SBE-β-CD) – chemiluminescence (CL) reaction system by paclitaxel. A linear relationship was found between the loss of CL and the quantities of paclitaxel with an equation of ΔI = (37.9±2.4) lnC + (127.6±5.2), allowing sensitive and fast determination of paclitaxel with a detection limit of 0.2 ng/mL (3σ) and relative standard deviations (RSDs) less than 4.0%. One assay’s recycle including sampling and washing procedure was accomplished in 36 s, providing a sample throughput of 100 h−1 under the optimum experimental conditions. Although the pharmacokinetic profiles of paclitaxel and its inclusion complex all accorded with one compartment open model, the area under the curve of paclitaxel from time zero to last sampling time (AUC0-t) was increased from 71.4±5.24 μg·h/mL to 96.7±4.62 μg·h/mL, whereby the absorption of paclitaxel was enhanced 1.35 folds through inclusion of SBE-β-CD. The proposed method has the potential to become a powerful alternative for pharmacokinetic study of paclitaxel due to the advantages of good linear range, high sensitivity and recovery as well as superior analytical efficiency.

A set of 36 compounds with local anesthetics properties and with the literature values of their biological activity was used to search for relationships between structural parameters obtained from semiempirical RM1 method. Ab initio calculations have been done for molecules in vacuo and also for their hydrated form by placing the molecule under consideration in an environment of water molecules. Finally the data examined the biological activity of compounds was related to their structural indicators using multiparametric regression analysis (multiple regression analysis) with a stepwise progressive method and additional artificial neural network analysis. No effect of hydration on the quantitative structure- activity relationships was observed, furthermore, the used set of independent variables (quantum-chemical parameters) derived from semiempirical calculation method described the properties of particles less than that obtained from the ab initio calculations.

Florfenicol is a synthetic and broad-spectrum antibiotic and developed for veterinary use. In this study, onestep membrane-based competitive colloidal gold-based immunochromatographic formats for the rapid detection of florfenicol were developed. The quality of colloidal gold particles was monitored by UV-vis spectroscopy. For the conjugation of colloidal gold and antibody, 24 μg/mL of antibody was confirmed to the optimal amount for stabilization of colloidal gold. With the prepared colloidal gold immunochromatography test strip was determined the standard florfenicol solution. The results demonstrated a detection limit of florfenicol was approximately 1.0 μg/mL. The study showed that the strip had a high sensitivity to florfenicol and without cross-reaction for other antibiotics. The results of 80 animal samples tests confirmed that 0 sample was higher than the detection limits by liquid chromatography-mass spectrometry (LC-MS). There was evidence to suggest that colloidal gold particles and GAB gold-labeled antibody were synthesized successfully. The prepared colloidal gold immunochromatography strip could be used for preliminary screening of florfenicol.

The present paper reports the development of novel, stable & validated RP HPLC method for the simultaneous estimation of Artemether (ART) and lumefantrine (LUM) in bulk and tablet dosage form. Good chromatographic separation was achieved by isocratic mode with a mixture of phosphate buffer: methanol in the ratio of 50: 50 as the mobile phase with waters symmetry Shield Rp18Column (250 mm x 4.6mm x 5) μm as stationary phase at a flow rate of 1.0 ml/min. The detection was performed at 273 nm. Retention time for LUM and ART were found 2.249 and 4.516 min respectively. The proposed method showed good intra-day precision (%RSD=0.068for ART, 0.033 for LUM), good accuracy (recovery for both ART and LUM > 99% ), and high correlation coefficient(R2= 0.999 both ATM and LUM). The detection and quantitation limits were 0.55 μg/ml and 1.35 μg/ml for ART and 0.09 μg/ml and 0.32 μg/ml for LUM. This method found to have a good percentage recovery in a forced degradation study using acid, base, oxidation, photolytic, thermal and neutral conditions indicates well separation of both the drugs with other degradation products and the present method has shown good solution stability. Hence, the present study reports ever developed stability indicating easiest method which is useful for the routine analysis.

Ticagrelor is an orally active, reversibly bind of the P2Y12 receptor that can prevent ADP-mediated platelet activation and has a faster onset of action than clopidogrel. A stability-indicating HPLC method for the determination of ticagrelor in coated tablets was developed and validated. Chromatographic analysis was performed in a Shimadzu liquid chromatograph, equipped with Phemomenex® C18 column (250 x 4.6 mm, 5 μm), using a mobile phase composed of acetonitrile: water with 0.5% triethylamine (57:43 v/v) pH 7.0, at 0.7 ml/min flow rate and injection volume of 20 μl. Under the conditions established, the method demonstrated to be specific, without interference from formulation excipients, stability- indicating, linear (r = 0.9990) in the concentration range of 45.0 to 105.0 μg/ml, precise (RSD=0.71), accurate (99.61% of mean recovery) and robust. It can be successfully applied to ticagrelor tablets quality control, being adequate for routine analysis.

Herein, we report cellulose sulfuric acid (CSA) as a heterogeneous, eco-friendly, reusable catalyst for the synthesis of β -indolylketones via conjugate Micheal addition reactions of indoles, to chalcones in acetonitrile at 80 °C for 1.5–4 h. The structures of the synthesized compounds were evaluated by spectral data. All the synthesized compounds were screened for their antimicrobial activity against bacterial (S. aureus, K. pneumonia and S. marcescens) and fungal (C. albicans and A. niger) strains. The aim of this study was to determine the relationship between lipophilicity and antimicrobial activity of β-indolylketones.

This review focuses on analytical methods for the determination of reactive oxygen species (ROS): a superoxide/ hydroperoxyl radical, hydrogen peroxide, singlet oxygen and a hydroxyl radical. The methods which are described in this paper are based on: electron paramagnetic resonance spectroscopy (EPR), nuclear magnetic resonance (NMR), mass spectroscopy (MS), spectroscopy UV-Vis, gas chromatography (GC), chemiluminescence (CL), fluorescence (FL), HPLC –UV, iodide titration, and 14C-formate oxidation. In this review, the most common analytical methods for the detection of ROS generated by chemical methods are presented. The methods are based on the direct as well as indirect detection of ROS.