The existence of multiple crystal forms in a drug substance poses interesting development challenges as the material is taken
from discovery through formulation, manufacture and market. There are a number of factors why drug substances under development
are screened for presence of multiple crystal forms. Different crystal forms may exhibit varied performance properties including
bioavailability and solubility, as well as, differences in physical properties such as morphology and melting point. These
properties can affect the design of the manufacturing processes for the bulk drug substance, the formulation and the performance
of the drug product. This paper will focus on the application of differential scanning calorimetry (DSC) for the quantitation
of pharmaceutical crystal forms. Feasibility studies were conducted on several pharmaceutical drug substances which were known
to have multiple crystal forms, to determine if quantitative, semi-quantitative or limit of detection tests could be developed.
The conclusion from these studies is that polymorphic crystal systems comprised of either close, or melting with decomposing,
endotherms, competing transitions, or that contain sample contaminants, may not be optimum candidates for quantitation by
DSC. Conversely, crystal systems that contain polymorphs that exhibit well-resolved endothermic or exothermic transitions,
for either solvated vs. unsolvated species or both unsolvated, may be excellent candidates for crystal form quantitation by DSC.
Authors:P. K. Gupta, V. V. Kuber, V. K. Ghosh, S. G. Bhope, V. Sharma, and S. Purohit
A simple, rapid, and specific thin layer chromatographic (TLC) method has been developed and validated for the simultaneous estimation of icariin and l-arginine from commercial polyherbal formulations for sexual dysfunction. The separation of the methanol extract of these formulations was achieved on silica gel 60 F254 aluminum backed TLC plates by using ethyl acetate-acetone-glacial acetic acid-formic acid-water 12:2:1:2:2 (υ/υ) as mobile phase. Densitometric analysis of icariin and l-arginine was monitored in absorbance mode at 270 and 195 nm, respectively. The linear regression analysis data for the calibration plots for icariin and l-arginine showed good linear relationship with r2 = 0.9984 +- 0.01 and 0.9968 +- 0.02, in the concentration ranges of 250–750 and 500–1500 ng/spot, respectively. The method was validated for precision, robustness, and recovery. The average percentage recovery was found to be 98.26% for icariin and 99.63% for l-arginine. The limits of detection and quantitation were 72, 116 and 238, 383 ng/spot, respectively, for icariin and l-arginine. Statistical analysis proves that the method is repeatable and selective for the estimation of the targeted drugs. Since the proposed mobile phase effectively resolves the icariin and l-arginine, this method can be applied for the identification and quantitation of these components in herbal extracts and marketed formulations.
Authors:Min Zhang, Zhenling Zhu, Mengyue Wang, Jincai Hou, Yinqing Li, and Xiaobo Li
, supplemented by an evaporative light-scattering detector (ELSD), and the rapid quantitation of multiple major marker compounds (see Fig. 1 ) of 16 batches of BYD prepared by the traditional procedure was conducted. These methods are more applicable for
Authors:Gellért Balázs Karvaly, Kornélia Tekes, Zoltán Szimrók, József FŰrÉsz, Kamil KuČa, and Huba Kalász
of the pharmacokinetics of several novel K-oximes, our aim is to present a high-throughput, cost-efficient, multiplexed approach relying on high performance liquid chromatography (HPLC) and ultraviolet (UV) detection for the quantitation of an
A sensitive and reliable high-performance thin layer chromatographic method has been developed for quantitation of camptothecin in the dry stem powder of
(Wight) Sleumer. A methanolic extract of the dry powder was chromatographed on silica gel 60F
plates with toluene-acetonitrile-glacial acetic acid, 6.5 + 3.5 + 0.1 (
), as mobile phase. Detection and quantitation were performed by densitometric scanning, in fluorescence mode at
= 370 nm, by use of a mercury lamp. The accuracy of the method was checked by determination of recovery, using the standard-addition method. Recovery was 99.49%. The average camptothecin content of the powder was 0.059%. The method is rapid, simple, and precise.
Authors:Louise Wiles, Timothy Olds, and Marie Williams
Bibliometric measurements, though controversial, are useful in providing measures of research performance in a climate of
research competition and marketisation. Numerous bibliometric studies have been performed which rely on traditional indices
(such as the journal impact factor and citation index) and provide little descriptive data regarding the actual characteristics
of research. The purpose of this study was two-fold, to develop three novel bibliometric indices, designed to describe the
characteristics of research (relating to evidence base, quantitation and collaboration), and to apply them in a cross-sectional
audit of original research articles published in Australian professional association journals across medicine, nursing and
allied health in 2007. Results revealed considerable variation in bibliometric indices across these journals. There were emerging
clusters of journals that published collaborative research using higher levels of evidence and reported quantitative data,
with others featuring articles using lower levels of evidence, fewer quantitative data and less collaboration among authors.
This article describes a new, simple, precise and accurate TLC method for simultaneous quantitation of atorvastatin (ATO), ezetimibe (EZE), and fenofibrate (FEN) as the bulk drug and in tablet dosage forms. Chromatographic separation of the drugs was performed on aluminum plates precoated with silica gel 60 F254 as the stationary phase and the solvent system consisting of chloroform-toluene-methanol-acetic acid 6:3:0.5:0.15 (υ/υ/υ/υ). Densitometric evaluation of the separated zones was performed at 263 nm. The drugs were satisfactorily resolved with RF values of 0.16 ± 0.02, 0.22 ± 0.02, and 0.76 ± 0.02 for ATO, EZE, and FEN, respectively. The accuracy and reliability of the method was assessed by evaluation of linearity (75–375 ng per spot for ATO, 99–594 ng per spot for EZE, and 66–330 ng per spot for FEN), precision intra-day and inter-day RSD values were always less than 1.51 for the titled drugs, accuracy (99.72 ± 0.75% for ATO, 101.25 ± 0.91% for EZE, and 101.06 ± 0.60% for FEN), and specificity, in accordance with ICH guidelines.
A sensitive, simple, and accurate reversed-phase high-performance thin-layer chromatographic method has been established for determination of protodioscin in fruit powder from
L. A methanol extract of the fruit powder was used for experimental work. Separation was performed on RP-18F
HPTLC plates with 0.1 m KH
-acetonitrile-methanol-triethylamine, 5 + 4 + 1 + 0.1 (
), as mobile phase. After development, plates were treated with 0.1 m H
and detection and quantification were performed by densitometry at
= 366 nm. Detection and quantitation limits were 0.03 μg and 0.05 μg, respectively. Response was a linearly dependent on amount of protodioscin in the range 0.05 to 1.00 μg. The validated RP-HPTLC method can be used for a routine quality-control analysis of
L. fruit powder and quantitative determination of protodioscin.
A sensitive, simple, and accurate high-performance thin-layer chromatographic method has been established for determination of oleanolic acid in whole-plant powder from
L. A methanol extract of the powder was used for the experimental work. The concentration of oleanolic acid in whole plant was found to be 1.892 μg g
. Separation was performed on aluminum HPTLC plates coated with silica gel 60 F
, with dichloromethane-toluene-acetone-methanol, 3 + 4 + 1.5 + 0.3 (
), as mobile phase. After development, plates were treated with
reagent and detection and quantification were performed by densitometry at
= 529 nm. Detection and quantitation limits were 0.1 μg and 0.5 μg, respectively. Oleanolic acid response was linear over the range 1 to 9 μg. The validated HPTLC method can be used for routine quality-control analysis of
L. whole-plant powder and for quantitative determination of oleanolic acid.