Development of Quantitative HPTLC-Densitometry Methods for Analysis of Fake and Substandard Pharmaceutical Products Following a Model Approach for Transfer of TLC Screening Methods: Albendazole, Amodiaquin + artesunate, Aciclovir, and Amoxicillin

Abstract

& A model procedure including sample and standard solution preparation, calibration curve establishment, assay of pharmaceutical products versus the label values, and validation of precision, accuracy, and sample peak purity and identification was applied for development of quantitative HPTLC-densitometry methods to be used in support of regulatory action against substandard and fake drugs. Methods for albendazole and amodiaquin þ artesunate combined tablets were transferred from semiquantitative, visual TLC screening methods contained in an FDA Compendium developed by Kenyon and Layloff and GPHF Minilab manuals for use in countries with limited resources. A method for aciclovir was adapted from a previously published HPTLC method. The new methods involve use of a limited number of inexpensive and relatively innocuous solvents, EMD Millipore Premium Purity silica gel 60 F 254 glass plates, automated standard and sample solution application with a CAMAG Linomat 4, and automated densitometry for detection, identification, and quantification with a CAMAG Scanner 3. Attempts to transfer Compendium and Minilab TLC methods for amoxicillin according to the model procedure were not successful, but a semiquantitative HPTLC-densitometry method on EMD Millipore cellulose F 254 glass plates is described. These new methods can be more fully validated according to International Conference on Harmonization (ICH) guidelines or by interlaboratory studies if their applications require.

Use of a model process for transfer of minilab TLC screening methods for quinine sulfate, mefloquine, and dihydroartemisinin—piperaquine phosphate tablets to quantitative HPTLC—densitometry methods

“…A literature search on January 8, 2015, using the ISI Web of Science found no TLC-densitometry method for any individual or combination dihydroartemisinin and/or piperaquine pharmaceutical products reported. As found earlier for the drugs artesunate [5] and artemether [4], heating of the plate for 5 min at 160 °C allowed dihydroartemisinin to be detected under 254 nm UV light (reagent-free thermochemical activation fluorescence quench detection). However, densitometric determination attempted at this wavelength was unsuccessful because the scans of the two drugs were not baseline separated at the levels applied within the calibra-tion ranges.…”

“…Peak purity and identity for all methods were confirmed by r-values of 0.99 for these tests. The model procedure acceptance criteria for validation of accuracy (recovery) 95-105% and RSD ≤3% [3][4][5][6][7] were met in all cases. Almost all tablets assayed in the range 90-110% of the label value as set by the U.S. Pharmacopeia, and all were within the 70-130% test range of the model procedure.…”

“…Analytical procedures described in detail in earlier papers [1][2][3][4][5][6] were used in this work unless otherwise noted. All tablet samples were ground with a mortar and pestle and dissolved with the aid of 10 min each of magnetic stirring and sonication, and a portion was syringe filtered to remove any undissolved inert ingredients before further dilution or direct application to the HPTLC plate.…”

“…Previously published papers [1][2][3][4][5][6] described a model process for transfer of qualitative/semiquantitative thin-layer chromatography (TLC) methods used to identify pharmaceutical products with quality defects to quantitative high-performance TLC (HPTLC)-densitometry methods that can be used to support regulatory sanctions. The model process includes sample and standard solution preparation, establishment of the calibration curve, assay of pharmaceutical products for drug active ingredients relative to the label value, validation of accuracy and precision of the new method using the standard addition method, and sample peak purity and identity tests.…”

Simultaneous densitometric determination of anthelmintic drug albendazole and its metabolite albendazole sulfoxide by HPTLC in human plasma and pharmaceutical formulations

“…Application of high‐performance thin‐layer chromatography (HPTLC) for the analysis of anthelmintic drugs has been the subject of very few reports. The literature presents only three methods for the determination of ABZ either alone (Nguyen & Sherma, ) or with other drugs in pharmaceutical preparations (Rasal, Dhaneshwar, Bhusari, & Suryan, ; Varghese, Vasanthi, & Ravi, ). Currently there is no HPTLC‐based method for ABZSO in any biological fluid.…”