title: Use of thin-layer chromatography to detect counterfeit sulfadoxine/pyrimethamine tablets with the wrong active ingredient in Malawi.
abstract: BACKGROUND
  Substandard and falsified anti-malarial medicines pose a serious threat to public health, especially in low-income countries. Appropriate technologies for drug quality analysis in resource-limited settings are important for the surveillance of the formal and informal drug market. The feasibility of thin-layer chromatography (TLC) with different solvent systems was tested using the GPHF Minilab in a study of the quality of sulfadoxine/pyrimethamine tablets in Malawi.
  
  
  METHODS
  Twenty eight samples of sulfadoxine/pyrimethamine tablets were collected from randomly selected health facilities of four districts of southern Malawi. A mystery shopper approach was used when collecting samples from illegal street vendors, and an overt approach for the other facilities. Samples were subjected to visual inspection, disintegration testing and TLC analysis. 10 samples were further investigated according to the methods of the US Pharmacopeia using high performance liquid chromatography (HPLC).
  
  
  RESULTS
  One sample was found to be falsified, containing a mixture of paracetamol tablets and co-trimoxazole tablets. These had been repackaged into paper strip packs labelled as a brand of sulfadoxine/pyrimethamine. TLC with different solvent systems readily proved that these tablets did not comply with their declaration, and provided strong evidence for the active pharmaceutical ingredients which were actually contained. Full pharmacopeial analysis by HPLC confirmed the results suggested by TLC for this sample, and showed two further samples to be of substandard quality.
  
  
  CONCLUSIONS
  Due to the absence of the declared anti-malarial ingredients and due to the presence of other pharmaceutical ingredients, the identified falsified medicine represents a serious health risk for the population. Thin-layer chromatography (TLC) using different solvent systems proved to be a powerful method for the identification of this type of counterfeiting, presenting a simple and affordable technology for use in resource-limited settings.
authors.affiliation: Pharmacy Department, College of Medicine, University of Malawi, Private Bag 360, Chichiri, Blantyre 3, Malawi.
authors.forename: Felix
authors.initials: F
authors.lastname: Khuluza
authors.affiliation: Mission for Essential Drugs and Supplies (MEDS), P.O. Box 78040-00507, Viwandani, Nairobi, Kenya.
authors.forename: Stephen
authors.initials: S
authors.lastname: Kigera
authors.affiliation: Global Pharma Health Fund e.V. (GPHF), Rotlintstraße 75, 60389, Frankfurt, Germany.
authors.forename: Richard W O
authors.initials: RW
authors.lastname: Jähnke
authors.affiliation: Pharmacy Department, College of Medicine, University of Malawi, Private Bag 360, Chichiri, Blantyre 3, Malawi. heide@uni-tuebingen.de.|Presented address: Pharmaceutical Institute, Eberhard-Karls-University Tuebingen, Auf der Morgenstelle 8, 72076, Tuebingen, Germany. heide@uni-tuebingen.de.
authors.forename: Lutz
authors.initials: L
authors.lastname: Heide
mesh_terms: D000082:Acetaminophen / Q000032:analysis; D000962:Antimalarials / Q000032:analysis*; D002855:Chromatography, Thin Layer / Q000295:instrumentation; D058110:Counterfeit Drugs / Q000032:analysis*; D004338:Drug Combinations; D005240:Feasibility Studies; D008295:Malawi; D011739:Pyrimethamine / Q000032:analysis*; D011786:Quality Control; D013413:Sulfadoxine / Q000032:analysis*; D013607:Tablets / Q000032:analysis; D013678:Technology, Pharmaceutical / Q000379:methods*; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000032:analysis
chemical_list: D000962:Antimalarials; D058110:Counterfeit Drugs; D004338:Drug Combinations; D013607:Tablets; D000082:Acetaminophen; C001205:fanasil, pyrimethamine drug combination; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D013413:Sulfadoxine; D011739:Pyrimethamine
keywords: Falsified medicines; GPHF Minilab; SSFFC medicinal products; Sulfadoxine/pyrimethamine; Thin-layer chromatography