Toxicokinetics Flashcards
Toxicokinetics
Study of the absorption, distribution, biotransformation, and excretion of toxic agents
Drug disposition
Study of the movement of drugs in the body across biological membranes from the time of absorption until elimination
What is it the most common route of exposure in toxicology?
Oral route
What are the 4 stages of drug distribution?
Absorption
Distribution
Biotransformation
Excretion
What is passive diffusion?
Transmembrane and paracellular movement
What is transmembrane passive diffusion?
The movement of water through aqueous protein channels or by flow resulting from osmotic or hydrostatic differences across the membrane
What is paracellular passive diffusion?
Transport of water is through intercellular aqueous pores
What is simple diffusion?
Bulk flow of water can carry with it small water soluble substances
What is facilitated diffusion?
A carrier mediated transport that DOES NOT NEED energy; a drug moves from high conc to low conc
What is active transport?
A carrier mediated transport that REQUIRES energy; drug moves across membrane from low conc to high
conc
In primary active transport, where does the energy come from?
Directly from ATP such as the Na/K ATPase
In secondary active transport, where does the energy come from?
Uses stored energy in the Na electrochemical gradient that was created using ATP in primary active transport
Pinocytosis
Specific type of endocytosis where the cell engulfs the drug molecules dissolved in water
Concentration gradient
In simple diffusion drugs move from high conc to low, in active transport drugs move from low to high which is why they require energy
Explain the relationship between lipid solubility and speed of crossing the membrane
The higher the lipid solubility of the drug, the faster it crosses the membrane