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28 Cards in this Set

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What are the different ways that drug transport can occur?
passive Diffusion
Filtration
Carrier Mediated transport
Receptor mediated endocytosis
Ion pair transport
What is the primary means of drug transport and what is the driving force behind it?
Passive diffusion driven by concentration gradient
What is Kp and what does it tell you (this in relation to non-electrolytes)?
Kp is the lipid water partition coefficient which is the ratio of drug in two immiscible phases: a nonpolar liquid and an aqueous buffer. (the non polar liquid being the membrane and the aqueous buffer being the environment)
How is Kp measured (this is in relation to non-electrolytes)?
KP = [drug] in lipid / [drug] in aqueous phase --> simply put Kp is the relative affinity of a drug for lipid and aqueous phases
Think of the relationship of the scale of pH and pKa:
pH < pKa - predominant forms: HA and BH+
pH = pKa - HA = A- and BH+ = B
pH > pKa - predominant forms: A- and B
What are the characteristics that determine filtrations?
pores or porous structures
Driving force bing pressure gradient
Size of compound relative to pore size
Lipid solubility
What are the two primary differences in Carrier mediated transport between Active Transport and Facilitated Diffusion?
Frst the similarities:
Drug-carrier complex formed
Reversibly binds
Carrier is slective
They can be saturated
Now for the differences:
Active - ATP dependent
Facilitated - not ATP dependent
Active - unidirectional
Facilitated - Bi directional
Oh yeah... Active can be inhibited.
What are four different pathways for receptor-ligand complexes?
Receptor recycles, ligand is degraded (Most common)
Receptor and ligand recycle
Receptor and ligand degraded
Receptor and ligand transported
What is a major disadvantage to oral enteral administration of drugs involving the liver?
First pass effect where the liver degrades or metabolizes the drug before it arrives at the target site due to portal circulation through the liver from the GI tract.
What are two enteral administration routes for drugs that bypasses the first pass effect?
Sublingual
Rectal - rectal has about 50% transport to the liver
what are the various methods of Parenteral Administration?
IV
IM
SubQ
What is the primary site of absorption for drugs through the GI tract and through what method?
Small Intestines through passive diffusion
Describe the function of each of the following formulation factors:
Fillers, Disintegrators, binders, lubricants
Fillers - add bulk to the tablet to make it larger
Disintegrators - causes tablet to break down into granules
Binders - holds the tablet together
Lubricants - prevents the tablet from sticking to machines
What is the definition of bioavailability and how do you calculate it?
The fraction of administered drug that reaches the systemic circulation
Bioavailability = (AUC oral)/(AUC injected) x 100
Since we've seen it a billion times this block!! What is the water distribution throughout the body?
Total Body water is 60% body weight which is 42L of a 70kg person
Intracellular fluid = 40% of body weight ~28L
Extracellular fluid = 20% of body weight ~14L
Subcategories for extracellular:
Plasma = 6% of body weight at ~4L
Interstitial Volume = 14% of body weight at ~10L
Where would a drug with a large molecular weight or one that binds to plasma proteins be mainly distributed?
Plasma volume
Where would a drug that is low molecular weight and hydrophilic most likely be?
Extracellular fluid
Where would a low molecular weight and hydrophobic drug be?
Intracellular fluid
If it was said that a drugs Volume of distribution is >70L how is this possible?
The drug must be accumulating and binding in tissues because recall that the Total body Water is only about 42L
How are drugs transferred through the capillary?
Filtration
Drugs binding to albumin can be divided into how many classes and what are they?
Two classes
Class I: given in doses less than the binding capacity of albumin (dose to capacity ratio is low, binding sites are in excess of available drugs)
Class II: given in doses that greatly exceed the number of albumin binding sites. (dose/capacity ratio is high, relatively high proportion of the drug exists in the free state and not bound to albumin)
Keep in mind competition for binding and the fact that administering class II drugs to a patient will cause a class I drug to come off and be more bioavailable. Would this be likely to increase or decrease side effects or toxicities caused by a drug?
Yes thats right... increase probably
What types of plasma proteins are there?
Albumin - primary serum protein responsible for drug binding (stronger affinity for weak acid and hydrophobic drugs)
Lipoproteins - binds only lipid-soluble drugs (capacity is dependent on lipid content... VLDL>LDL>HDL)
Alpha 1-acid glycoprotein - one high affinity binding site and binds only basic drugs (its plasma concentration is inducible by acute injury, trauma, and stress which would decrease the amount of free drug available)
Where are there barriers to drug distribution?
Blood Brain barrier - passive diffusion or carrier mediated of lipid soluble drugs
Placental transfer barrier
Blood Testicular Barrier (I wonder if that implies that you can think with your ****?)
What are some sites for drug excretion?
Kidney:
Glomerular filtration
Active Secretion
Passive Reabsorption
Liver
Pulmonary Excretion
Sweat & Saliva
Milk
What types of plasma proteins are there?
Albumin - primary serum protein responsible for drug binding (stronger affinity for weak acid and hydrophobic drugs)
Lipoproteins - binds only lipid-soluble drugs (capacity is dependent on lipid content... VLDL>LDL>HDL)
Alpha 1-acid glycoprotein - one high affinity binding site and binds only basic drugs (its plasma concentration is inducible by acute injury, trauma, and stress which would decrease the amount of free drug available)
Where are there barriers to drug distribution?
Blood Brain barrier - passive diffusion or carrier mediated of lipid soluble drugs
Placental transfer barrier
Blood Testicular Barrier (I wonder if that implies that you can think with your ****?)
What are some sites for drug excretion?
Kidney:
Glomerular filtration
Active Secretion
Passive Reabsorption
Liver
Pulmonary Excretion
Sweat & Saliva
Milk