Drug Transporters (Caroline)

Drug Transporters (Caroline) - Drug Transporters

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Drug Transporters Drugs cross via passive diffusion Transcellular or paracellular (between cells) o Drugs use transcellular pathway more frequently Passive-down concentration gradients-no accumulation Not specific for structure or cell type Carrier-mediated transport: specific transport proteins in the membrane (on each  side) Absorb or excrete drugs Balance between all transporters that determines how fast into blood Transport can be inhibited Dependent on structure/cell type Diffusion Passive, substrates move down electrochemical gradient Will stop when concentration = on both sides Active transport Transport drugs into cell against the electrochemical gradient, requires ATP or  other substrate gradients Intestinal drug absorption Depends on drug if diffused, transporter, or combo of 2 ACE inhibitors/cimetidine absorption via passive diffusion o High concentrations in lumen, gives favorable gradient for diffusion Abx, methotrexate (folic acid derivatives), AA derivatives (l-dopa) substrates  for nutrient transporters, but hydrophilic Liver, BBB, kidney: carrier-mediated more important Carrier-Mediated transport If charged, water soluble, require a transporter cannot cross lipid bilayer But if hydrophobic, a transporter will increase the rate that it goes across 
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Drug Transporters (Caroline) - Drug Transporters

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