General Principles Flashcards
Transmembrane movement
Diffusion through lipid membranes and aqueous protein channels in the cell membrane
Basic drugs ionize in (acidic/basic) environments.
Basic drugs ionize in (acidic/basic) environments.
Lipid/Water Partition Coefficient
Measure of the diffusional mobility of a particular molecule
pKa is equal to
pKa is equal to the pH of the medium at which the dissolved drug is 50% ionized and 50% nonionized
Gene that encodes the permeability glycoprotein system (p-gp)
MDR-1 / ABCB-1 Gene
Secondary Active Transport
Uses stored energ in the Na electrochemical gradient generated by using ATP
Paracellular movement
Diffusion through intercellular aqueous channels
The cell membrane is composed of a
The cell membrane is composed of a lipid bilayer and embeded proteins
Most drugs are (weak/strong) acids or bases
Most drugs are (weak/strong) acids or bases
Membranes are more permeable to (nonionized/ionized) forms of drugs.
Membranes are more permeable to (nonionized/ionized) forms of drugs.
Components of the ADME process
Absorption
Distribution
Metabolism
Elimination
Permeability glycoprotein system (P-gp)
Drug transporter that removes drugs after being absorbed into specific cells or tissue sites
___________________
Associated with the multple drug resistance family
Active transport
Carrier-mediated transport, movement is against the gradient and requires energy
Drug Efflux
Membrane pump that “bounces” drug out of a cell
Ion Trapping
Weak acids are absorbed from an acidic environment and sequestered in an alkaline medium
______________
Weak bases are absorbed from an alkaline environment and sequestered in an acidic environment
Transport mechanisms across cell membranes
Simple/Passive Diffusion
Facilitated Diffusion (Passive Transport)
Active Transport
Pinocytosis
Ionization equation for a weak acid
pKa = pH + log N/I
Acidic drugs ionize in (acidic/basic) environments.
Acidic drugs ionize in (acidic/basic) environments.
Ionization equation for a weak base
pKa = pH + log I/N
Disposition
Study of movment of drugs across biological membranes in the body from teh time of absorption until elimination
Pinocytosis
Type of endocytosis, drug binds to the surface of the membrane that then invaginates and interiorizes the drug, requires ATP
Channel Mediated
Transport across the membrane involves opening of ion channel proteins
Facilitated Diffusion
Movement with the concentration gradient, no energy required
What are the factors that determine whether a drug will pass through a membrane
pKa
Ionization
Solubility
pH of medium
Carrier-Mediated Transport
Transfer of substance across the membrane involves attachment to a specific macromolecular carrier
Movement with a concentration gradient moves from
Movement with a concentration gradient moves from high to low concentration
Primary Active Transport
Uses energy directly from ATP
