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 + 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 F₂₅₄ 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 F₂₅₄ 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.

Keywords:

• aciclovir
• albendazole
• amodiaquin
• amoxicillin
• artesunate
• densitometry
• fake drugs
• model method for TLC to HPTLC transfer
• thin layer chromatography

ACKNOWLEDGMENT

The authors thank Thomas Layloff, Senior Quality Assurance Advisor, Supply Chain Management System (SCMS), Arlington, VA, for his support of this research; reviewing the manuscript prior to its submission for publication; and arranging for delivery of the albendazole, amodiaquine + artesunate, and aciclovir pharmaceutical samples supplied by the Dar es Salaam, Tanzania, office of SCMS. We also thank Dave Lentz of EMD Millipore Corp., Billerica, MA, a division of Merck KGaA, Darmstadt, Germany for supplying the HPTLC glass plates used. Mai Nguyen was supported by the Lafayette College EXCEL Scholar Program.

Notes

Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/ljlc.