Drug Disposition Flashcards
(34 cards)
What is passive diffusion?
Movement from a high concentration gradient to an area of low concentration.
What are the two types of simple passive diffusion?
Paracellular and transmembrane
What is paracellular movement?
Diffusion through intercellular aqueous channels and specialized intercellular junctions.
What is transmembrane movement?
Diffusion through lipid membranes and aqueous protein channels in the cell membrane. “Bulk flow movement” due to osmotic or hydrostatic differences.
The more hydrophobic or lipophilic the _____ the movement across a membrane.
Faster
What is the lipid/water partition coefficient?
The relative solubility of a drug as compared to its solubility in water
The _____ the lipid solubility, the _____ it crosses cell membranes.
Two possible answers
1 higher, faster
2 lower, slower
What is diffusion coefficient?
A measure of the diffusion all mobility of a particular molecule.
Depends on
Molecular size, molecular conformation, degree of ionization
Is energy required for passive transport?
No, transport is accomplished by movement from high to low concentration.
What is carrier mediated diffusion?
Transfer of substance across the membrane requires attachment to s specific macromolecular “carrier”
May or may not be specific
THIS SYSTEM IS SATURABLE
(100 students 1 door, as opposed to 5 students and 5 doors)
What is channel mediated transport?
Transport across a membrane facilitated by opening of ion channel proteins.
What is drug disposition?
The study of the movement of drugs across biological membranes in the body from the time of absorption until elimination.
What do you know about active transport?
Carrier mediated transport
Saturable, selective
Movement against concentration gradient
REQUIRES ENERGY
What’s the deal with primary active transport?
Direct usage of ATP to facilitate transport (nak atpase) (it’s back)
What is secondary active transport?
Secondary is indirect usage of ATP, primary will pump ions in and out of the cell to create a gradient. This gradient allows for SECONDARY active (using the energy of the ion gradient) to move substances in or out of cells.
What’s a symporter?
Both substances go the same direction through the membrane transport protein both in or both out.
Ex Na GLU transport in kidneys.
Once upon a midnight studying session the anxious caffeine addicted vet student stumbled upon an antiporter and found that it was unique in which ways?
One or more substances is going into the cell while one or more substances are leaving the cell. IN THE SAME TRANSPORT PROTEIN!
Drug efflux is what? Where is an important place it’s found, and why can collies not have ivermectin?
P-gp - permeability glycoprotein system. BOUNCERS of the cell, too many hooligans and this glycoprotein throws them out of the cell.
Pinocytosis, it’s in the piña colada family…
A type of endocytosis
Drug binds to the surface of the membrane
Membrane then surrounds and invaginates the drug
Brings drug inside the cell
Ex. Taking a shot of alcohol
Ex. Aminoglycosides in Renal tubular cells
True/false
Membranes are more permeable to non ionized drugs than ionized drugs?
True
What is the concentration percentage of a drug that is ionized when the ph of the medium is the drugs pka?
50% if you have trouble with this concept don’t wait find someone who can help (vet peepers, tas, tutors, professor)
What environment ionizes acidic drugs
Basic
What type of environment ionizes basic drugs
Acidic
Drug with high ionization in acidic medium
Weak base
