The European Pharmacopoeia (Ph. Eur.) Commission has decided to accept semi-quantitative High-Performance Thin-Layer Chromatography (HPTLC) tests as an alternative quality control which could be used instead of liquid chromatography (LC) assays in monographs on Traditional Chinese Medicines (TCM). The use of the HPTLC test, which aims at maintaining the level of quality control provided by the monograph without requiring additional assays, will be limited for the time being to monographs on herbal drugs used in TCM that are not subject to marketing authorisations.
The decision, which was taken during the 163rd session of the Ph. Eur. Commission, is the result of a pilot study on the use of the HPTLC method for a semi-quantitative evaluation of the levels of a marker. The study was initiated following Ph. Eur. users’ feedback and was carried out by the TCM working party of the Ph. Eur. to assess the possible replacement of HPLC assays in monographs on TCM. The semi-quantitative approach involved evaluating the intensity of the spot due to the marker in the test solution and comparing it with the intensity of the same spot in a reference solution containing the marker at a concentration equal to the limit.
The method was tested in collaborative trials to evaluate whether it was robust and reproducible. The trial involved several laboratories and samples that were representative of current batches with marker contents above and below the provisional limit.
After one year of work, the pilot study was successfully completed for Thunberg fritillary bulb (Fritillaria thunbergii Miq.: Beimu) and Corydalis rhizome (Corydalis yanhusuo W. T. Wang: Yanhusuo). The participating laboratories obtained reproducible results for marker levels, identity and system suitability using HPTLC, which was also found to give the same pass/fail results as the HPLC assay. Marker levels were evaluated by visual inspection or using appropriate software which converted the HPTLC chromatogram into peak profiles.