Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
61 Cards in this Set
- Front
- Back
|
The most important determinant of the rate of passive drug movement across a membrane
|
Concentration gradient of diffusible drug
|
|
|
The easiest way to increase the rate of passive drug movement
|
Increase dose of diffusible drug
|
|
|
Characteristics of a drug that influence passive diffusion
|
molecular weight (inversely), lipophilicity (PC; directly); ionization (pKa; inversely)
|
|
|
Characteristics of the patient that impact passive drug diffusion.
|
Surface area (directly), membrane thickness (inversely), permeability (directly), blood flow (directly)
|
|
|
A type of carrier-mediated transport which requires energy
|
Active transport
|
|
|
A type of carrier mediated transport which does not require energy
|
Facilitated diffusion
|
|
|
These structures in capillaries allow unimpeded passive drug movement into interstitial tissues.
|
Fenestrae, pores or windows (non-tight junctions)
|
|
|
These structures in capillaries prevent passive movement of all but very lipid soluble drugs into sanctuaries.
|
Tight junctions
|
|
|
A drug characteristic important to drug movement into sanctuaries.
|
Lipophilicity
|
|
|
The state of an ionizable drug when it is in a "like" environment
|
Unionized, diffusible
|
|
|
The most important determinant of the rate of passive drug movement across a membrane
|
Concentration gradient of diffusible drug
|
|
|
The easiest way to increase the rate of passive drug movement
|
Increase dose of diffusible drug
|
|
|
Characteristics of a drug that influence passive diffusion
|
molecular weight (inversely), lipophilicity (PC; directly); ionization (pKa; inversely)
|
|
|
Characteristics of the patient that impact passive drug diffusion.
|
Surface area (directly), membrane thickness (inversely), permeability (directly), blood flow (directly)
|
|
|
A type of carrier-mediated transport which requires energy
|
Active transport
|
|
|
A type of carrier mediated transport which does not require energy
|
Facilitated diffusion
|
|
|
These structures in capillaries allow unimpeded passive drug movement into interstitial tissues.
|
Fenestrae, pores or windows (non-tight junctions)
|
|
|
These structures in capillaries prevent passive movement of all but very lipid soluble drugs into sanctuaries.
|
Tight junctions
|
|
|
A drug characteristic important to drug movement into sanctuaries.
|
Lipophilicity
|
|
|
The state of an ionizable drug when it is in a "like" environment
|
Unionized, diffusible
|
|
|
A weak base is located in a pH of 5. Is this "like" or "unlike"?
|
Unlike because the pH is acidic (< 7.0)
|
|
|
A weak base located in an pH more than 2 pH units below its pKa will be in this state.
|
Ionized, trapped
|
|
|
If a weak base with a pKa of 8 is located in a pH of 7, the ratio of the drug that is unionized to ionized
|
10 (-1):1 or 0.1:1
|
|
|
If a weak base with a pKa of 8 is located in a pH of 9, the ratio of the drug that is unionized to ionized.
|
10(1):1 or 10:1
|
|
|
The site of most oral absorption
|
Small intestine
|
|
|
A lipid soluble drug will undergo this drug movement in the renal tubular lumen
|
Passive reabsorption
|
|
|
A measure of drug lipophilicity based on distribution of drug in a water and lipid phase
|
Partition Coefficient
|
|
|
Definition of pKa
|
The pH at which an ionizable drug is present in equal parts ionized versus unionized
|
|
|
In order for the 4 drug movements (A,D,M,E) to occur, passage must occur through what?
|
biological (cell) membranes
|
|
|
Of the 4 drug movements,which two determine plasma drug and tissue receptor site concentrations?
|
Absorption and distribution
|
|
|
Of the 4 drug movements, which two terminate drug action?
|
biotransformation (metabolism) and excretion
|
|
|
The building blocks of cell membranes.
|
Phospholipids
|
|
|
The first step for or barrier to drug movment.
|
The cell membrane (phosplipid bilayer)
|
|
|
Drugs move across membranes by either of these two major movements.
|
Passive diffusion or active transport processes
|
|
|
By far the most important mechanism of drug transfer throughout the body.
|
simple diffusion
|
|
|
The rate of drug movement by simple diffusion is (fill in the blank) proportional to the concentration gradient, and lipophilicity of the drug molecule, and inversely proportional to the molecular weight and membrane thickness.
|
directly
|
|
|
This type of molecule readily crosses the lipid bilayer and move throughout the body.
|
small, uncharged
|
|
|
In order for this type of molecules to cross the lipid bilayer, specific carriers or specific ion channels will be needed.
|
large, polar
|
|
|
The two types of passive diffusion.
|
simple and facilitated
|
|
|
This type of transport (two words) can take a passive or active form.
|
carrier mediated
|
|
|
This type of inhibition (two words) is a characteristic of carrier mediated transport.
|
Competitive inhibition
|
|
|
The type of transport requires energy?
|
Active transport
|
|
|
The only way substances that cannot cross the bilayer through simple diffusion can penetrate a cell membrane.
|
channels or carrier mediated protein
|
|
|
This type of transport is against the concentration gradient.
|
Active transport
|
|
|
An example of a substrate that moves into a cell by facilitated diffusion
|
glucose, which is facilitated by insulin.
|
|
|
Drug being carried into the glomerulus along with the blood is an example of (fill in the blank)
|
bulk flow
|
|
|
The proximal convuluted nephron is a common example of this type of transport
|
Active transport
|
|
|
A class of drugs which are readily secreted into the lumen of the nephron through active secretion.
|
antibiotics (there are many others; what type of infection would this help?)
|
|
|
Passive transport processes can lead to reabsorption (for example, in the nephron) if the drug is…?
|
lipid soluble and in an unionized form.
|
|
|
The term used to describe passive transport in the neprhon that takes the drug OUT of the tubular lumen.
|
Resorption
|
|
|
Lipid solubility is important for drugs that must cross these two organs of drug entry.
|
Skin, GI epithelium
|
|
|
Even the majority of ionized species cross peripheral capillary beds of muscles with ease due to this characteristic of the capillaries.
|
Fenestrae, pores or windows (non-tight junctions)
|
|
|
The cut-off molecular weight that allows movement through the pores of the capillary wall.
|
60,000 KD
|
|
|
In general, most drugs are weak …?
|
acids or bases.
|
|
|
In general, most drugs are present in solution as both the (blank) and (blank) species or molecule.
|
nonionized and ionized
|
|
|
Nonionized or ionized (choose one) molecules are usually lipid-soluble and can diffuse across the cell membrane.
|
nonionized
|
|
|
The degree of ionization of a drug depends on its pKa of the drug, or the dissociation constant and the (fill in the blank) of its environment.
|
pH
|
|
|
A weak acid is more likely to be ionized if it is located in a (fill in the blank) environment.
|
basic
|
|
|
For a weak base, a pH higher or lower (pick one) than the pKa of the drug increases the amount of unionized drug and the ratio of U:I increases.
|
higher
|
|
|
For a weak base, as the pH decreases, the environment becomes more unlike the drug and the ratio of (U:I) decreases or increases (pick one).
|
decreases
|
|
|
Assume a drug is in an “unlike” environment. It is ionized and unable to move across membranes. What is the term used to refer to such a state (in terms of drug movement)?
|
ion trapping
|
