The effect of water pH on the uptake of acidic (ibuprofen) and basic (propranolol) drugs in a fish gill cell culture model

Elisabeth Dohmann Chang, Raewyn M. Town, Stewart F. Owen, Christer Hogstrand, Nic R. Bury

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7 Citations (Scopus)
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Water pH is predicted to affect the uptake of ionisable pharmaceuticals in fish. The current study used an in vitro primary fish gill cell culture system (FIGCS) to assess the effect of pH-values in the range of 4.5 – 8.75 on the uptake rates of the base propranolol (pKa 9.42) and the acid ibuprofen (pKa 4.59). The rate limiting step in uptake was the diffusive supply flux of the unionised form from the water to the apical membrane, with subsequent rapid transfer across the epithelium. Computed uptake rate based on the unionised fraction best described the uptake of propranolol and ibuprofen over the range of pH values 5 – 8 and 6 – 8.75 values, respectively. For ibuprofen the computed uptake rate overestimated uptake below pH 6 where the unionised fraction increased from 4% at pH 6 to 55% at pH 4.5. As the unionised fraction increased the uptake rate plateaued suggesting a saturation of the transport process. For both drugs large variations in uptake occur with only small fluctuations in pH values. This occurs between pH 6 to 8 values, the pH range acceptable in regulatory test guidelines and seen in most of our freshwaters.
Original languageEnglish
Pages (from-to)6848–6856
Number of pages9
JournalEnvironmental Science and Technology
Issue number10
Early online date16 Mar 2021
Publication statusPublished - 18 May 2021


  • Environmental pharmaceuticals
  • Uptake
  • Modelling
  • Bioconcentration
  • Accumulation
  • Pollution
  • Environmental Contamination
  • pharmaceuticals
  • APIs
  • pH
  • Gill
  • Rainbow trout


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