Module 1 Lec 1 Flashcards
what are the 4 ADME processes?
Absorption, Distribution, Biotransformation, Excretion
what is Exposure defined as?
a condition that provides an opportunity for a xenobiotic to enter the body
Units in PPM (parts per million) or unit of weight per area
what is Dose defined as?
Amount of chemical absorbed
different doses can result from same exposure
what are the Passive Transport systems? What movement is present in them?
Simple Diffusion & Filtration
Chemicals move from regions of higher
concentration to regions of lower concentration
without any energy expenditure
what 3 Factors on affect the absorption of Hydrophobic Chemicals
- Lipid solubility
- Molecular Size
- Degree Of Ionization
how is Lipid solubility measured?
determined by octanol:water partition coefficient
positive values associated with high lipid solubility
explain Degree Of Ionization
many chemicals are weak organic acids or base
exist in ionized (less soluble) or non-ionized (more soluble) form
depends on the pH of the solution
what is the equation for Octanol/Water Partition Coefficient? what values enter cells easier?
P = [conc. in octanol]/[conc. in water]
higher P’s enter cells easier
how does Filtration transport occur?
Small solutes can pass with bulk water
through pores/channels in a membrane
Size of the channels can vary with
tissue/organ
what are the 3 Special Transport systems?
Facilitated diffusion
Active transport
Additional Transport Processes
how does Facilitated Diffusion move molecules and what other transport is it similar to? How is it similar? what is the difference?
Facilitated diffusion is similar to
simple diffusion in that it does not
require energy and follows
a concentration gradient.
The difference is that it is a carrier mediated transport mechanism
• special transport proteins facilitate
movement of molecules across the
membrane
• faster and capable of moving larger
molecules that have difficulty diffusing
through the membrane without a carrier
in what direction does Active Transport move molecules? what is required?
Active transport processes exist in
which movement through the
membrane may be against
the concentration gradient
(ATP) is required
what are the 2 Special Transport categories?
- active, energy dependent transporters
of the large superfamily known as
ATP-binding cassette - solute carriers (SLCs) that
predominantly function through
facilitative diffusion
What are the three ways that
environmental chemicals can
alter/affect drug transporters?
- can inhibit transport activity directly
- disrupt hormone production, affecting carrier-mediated transporters
- May cause inflammation which can alter transporter expression
what are 3 Additional Transport Processes?
Phagocytosis
Pinocytosis
Recepror mediated endocytosis
