title: Biodegradability and ecotoxicitiy of tramadol, ranitidine, and their photoderivatives in the aquatic environment.
abstract: OBJECTIVE
  This study was designed to assess the fate and the overall potential impacts of the widely prescribed drugs ranitidine and tramadol after their introduction into the aquatic environment.
  
  
  METHODS
  The probability to detect these two drugs in the aquatic environment was studied by analyzing their abiotic and biotic degradation properties. For this purpose, samples were irradiated with different light sources, and three widely used biodegradability tests from the OECD series, the closed bottle test (OECD 301 D), the manometric respirometry test (OECD 301 F) and the Zahn-Wellens test (OECD 302 B), were conducted. The ecotoxicity of the photolytically formed transformation products was assessed by performing the bacterial growth inhibition test (EN ISO 10712). Furthermore, quantitative structure-activity relationship analysis and a risk analysis based on the calculation of the predicted environmental concentrations have also been conducted to assess the environmental risk potential of the transformation products. The possible formation of stable products by microbial or photolytical transformation has been investigated with DOC and LC-MS analytics.
  
  
  RESULTS
  In the present study, neither ranitidine, nor tramadol, nor their photoderivatives were found to be readily or inherently biodegradable according to test guidelines. The photolytic transformation was faster under a UV lamp compared to the reaction under an Xe lamp with a spectrum that mimics sunlight. No chronic toxicity against bacteria was found for ranitidine or its photolytic decomposition products, but a low toxicity was detected for the resulting mixture of the photolytic transformation products of tramadol.
  
  
  CONCLUSIONS
  The study demonstrates that transformation products may have a higher environmental risk potential than the respective parent compounds.
authors.affiliation: Department of Environmental Health Services, University Medical Center Freiburg, Freiburg, Germany.
authors.forename: Marlies
authors.initials: M
authors.lastname: Bergheim
authors.forename: Reto
authors.initials: R
authors.lastname: Gieré
authors.forename: Klaus
authors.initials: K
authors.lastname: Kümmerer
mesh_terms: D001673:Biodegradation, Environmental; D004305:Dose-Response Relationship, Drug; D054750:Ecotoxicology / Q000379:methods*; D010782:Photolysis / Q000187:drug effects*; D016958:Pseudomonas putida / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D011899:Ranitidine / Q000633:toxicity*; D018570:Risk Assessment; D018675:Toxicity Tests; D014147:Tramadol / Q000633:toxicity*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D014978:Xenon
chemical_list: D014874:Water Pollutants, Chemical; D014147:Tramadol; D014978:Xenon; D011899:Ranitidine