Authors:D. Kiss, R. Zelkó, Cs. Novák, and Zs. Éhen
The purpose of the present
work was to study the compatibility of metronidazole with different pharmaceutical
excipients (hydroxypropyl methylcellulose, poly(ethylene oxide), microcrystalline
cellulose, dicalcium phosphate dihydrate, and anhydrous dicalcium phosphate)
using differential scanning calorimetry and diffuse reflectance spectroscopy.
Dicalcium phosphate dihydrate was the only excipient that showed interaction
with metronidazole even before storage. Changes referring to a possible transition
to dihydrate form were observed in the thermal curves of anhydrous dicalcium
phosphate after four weeks of storage. Although dicalcium phosphate dihydrate
can be replaced by the anhydrous form in pharmaceutical formulations, the
observed transition might negatively influence the stability of dosage forms.
This study applies the artificial neural network technique to explore the influence of quantitative and qualitative patent
indicators upon market value of the pharmaceutical companies in US. The results show that Herfindahl-Hirschman Index of patents
influences negatively market value of the pharmaceutical companies in US, and their technological independence positively
affects their market value. In addition, this study also finds out that patent citations of the American pharmaceutical companies
have an inverse U-shaped effect upon their market value.
A model process was previously developed [ 1 – 3 ] for transferring visual, semiquantitative thin-layer chromatography (TLC) screening methods for pharmaceutical products with quality defects in the Global Pharma
Authors:Orsolya Jójárt-Laczkovich and Piroska Szabó-Révész
Amorphization is nowadays a method that is frequently applied in the pharmaceutical industry. The primary aim of this study
is to achieve the amorphization of clopidogrel hydrogen sulphate as an active pharmaceutical ingredient (API) with various
solvents and to choose the most suitable one. A secondary aim was to determine the glass-transition temperature (Tg) of this API and to classify it as a good or poor glass former. To investigate the amorphous form, differential scanning
calorimetry, X-ray powder diffraction, and FT-IR analysis were applied. The melting point (Tm) was 177.4 °C (450.6 K), and Tg was determined to be 88.9 °C (362.1 K). The quotient Tg/Tm was 0.80, and this API was therefore classified as a good glass former.
Authors:Marcin Koba, Katarzyna Koba, and Tomasz Bączek
A UV densitometric high-performance thin-layer chromatographic (HPTLC) method for analysis of nitrazepam in pharmaceutical formulations is described. Chromatography was performed on silica gel F254 plates with benzene-ethanol 5:1 (v/v) as mobile phase. Densitometric detection was at 196 nm. Under these conditions the RF of nitrazepam was 0.68. The method provided good results, but only when calibration was performed by non-linear regression analysis, with fitting to the equation y = bxm. The method can be used for routine quality-control analysis of nitrazepam in pharmaceutical formulations. Quantification was achieved over the range of 0.25–10.0 μg per spot. Mean recovery was 98.86% and 98.80 % for tablet and pure powder, respectively. Precision and accuracy, expressed as RSD (relative standard deviation) were 1.26% and 1.18%, respectively. The was no interference from tablet excipients in the assay procedure. The method was validated and found to be sufficiently precise and reproducible.
An isocratic reversed-phase high-performance liquid chromatographic (RPHPLC) method for analysis of irinotecan HCl has been developed and validated. Separation was achieved on a C18 column with potassium dihydrogen phosphate buffer (pH adjusted to 3.5 with orthophosphoric acid)-acetonitrile-methanol 55:25:20 (v/v) as mobile phase at a flow rate of 1.0 mL min−1. UV detection was performed at 254 nm. The method is simple, sensitive, rapid, and selective, and linear over the range 30–70 μg mL−1 for assay of irinotecan HCl. The precision of the assay method was below 1.0% RSD. Mean recovery was in the range 98.0–102.0%. Recovery of the active pharmaceutical ingredient from dosage forms ranged from 99.0 to 101.0. The method is useful for quality control in bulk manufacture and of the pharmaceutical formulation.
Authors:Ehab Abourashed, Maged Abdel-Kader, and Abdel-Azim Habib
A high-performance thin-layer chromatographic (HPTLC) method has been established for determination of sildenafil citrate in commercial products. The compounds were separated on silica gel, with CHCl
-MeOH-diethylamine, 90 + 10 + 1 (
), as mobile phase, and the analyte spots were quantified densitometrically at
= 305 nm. Recovery of sildenafil citrate was 100.6 and 98.2%, for pure and spiked samples, respectively. Method precision and specificity were also validated. The method was used for determination of sildenafil in four pharmaceutical products and three aphrodisiac herbal preparations which were claimed to be totally natural. Levels of sildenafil in the pharmaceutical products ranged from 49.7 to 50.5 mg per tablet. Sildenafil was also detected in one herbal preparation at a concentration of 85.0 mg per capsule.