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28 Cards in this Set
- Front
- Back
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What are the different ways that drug transport can occur?
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passive Diffusion
Filtration Carrier Mediated transport Receptor mediated endocytosis Ion pair transport |
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What is the primary means of drug transport and what is the driving force behind it?
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Passive diffusion driven by concentration gradient
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What is Kp and what does it tell you (this in relation to non-electrolytes)?
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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)
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How is Kp measured (this is in relation to non-electrolytes)?
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KP = [drug] in lipid / [drug] in aqueous phase --> simply put Kp is the relative affinity of a drug for lipid and aqueous phases
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Think of the relationship of the scale of pH and pKa:
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pH < pKa - predominant forms: HA and BH+
pH = pKa - HA = A- and BH+ = B pH > pKa - predominant forms: A- and B |
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What are the characteristics that determine filtrations?
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pores or porous structures
Driving force bing pressure gradient Size of compound relative to pore size Lipid solubility |
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What are the two primary differences in Carrier mediated transport between Active Transport and Facilitated Diffusion?
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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. |
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What are four different pathways for receptor-ligand complexes?
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Receptor recycles, ligand is degraded (Most common)
Receptor and ligand recycle Receptor and ligand degraded Receptor and ligand transported |
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What is a major disadvantage to oral enteral administration of drugs involving the liver?
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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.
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What are two enteral administration routes for drugs that bypasses the first pass effect?
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Sublingual
Rectal - rectal has about 50% transport to the liver |
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what are the various methods of Parenteral Administration?
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IV
IM SubQ |
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What is the primary site of absorption for drugs through the GI tract and through what method?
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Small Intestines through passive diffusion
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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 |
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What is the definition of bioavailability and how do you calculate it?
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The fraction of administered drug that reaches the systemic circulation
Bioavailability = (AUC oral)/(AUC injected) x 100 |
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Since we've seen it a billion times this block!! What is the water distribution throughout the body?
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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 |
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Where would a drug with a large molecular weight or one that binds to plasma proteins be mainly distributed?
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Plasma volume
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Where would a drug that is low molecular weight and hydrophilic most likely be?
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Extracellular fluid
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Where would a low molecular weight and hydrophobic drug be?
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Intracellular fluid
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If it was said that a drugs Volume of distribution is >70L how is this possible?
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The drug must be accumulating and binding in tissues because recall that the Total body Water is only about 42L
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How are drugs transferred through the capillary?
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Filtration
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Drugs binding to albumin can be divided into how many classes and what are they?
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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) |
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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?
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Yes thats right... increase probably
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What types of plasma proteins are there?
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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) |
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Where are there barriers to drug distribution?
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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 ****?) |
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What are some sites for drug excretion?
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Kidney:
Glomerular filtration Active Secretion Passive Reabsorption Liver Pulmonary Excretion Sweat & Saliva Milk |
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What types of plasma proteins are there?
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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) |
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Where are there barriers to drug distribution?
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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 ****?) |
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What are some sites for drug excretion?
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Kidney:
Glomerular filtration Active Secretion Passive Reabsorption Liver Pulmonary Excretion Sweat & Saliva Milk |
