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48 Cards in this Set
- Front
- Back
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What is biotranslocation? |
Study of drug absorption and distribution |
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What is biotransformation? |
Study of the chemical alterations a drug may undergo in the body |
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What are the qualities of a 'perfect' drug? |
Stable form, reaches biological target, remains in the body long enough to have therapeutic effect, does not produce harm in the body, and exits the body when done |
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What determines the rate of absorption of a drug? |
The balance between the lipophilic and hydrophobic nature of the drug |
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What is the downside of drugs which are too lipophilic? |
They are insoluble in an aqueous media, bind to strongly to plasma proteins and distribute into the lipid bilayer |
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What is the downside of drugs which are too hydrophilic? |
They are unable to cross the plasma membrane |
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What is logP? |
A measure of a drug's lipophilicity |
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How are biopharmaceutics classes? |
How easily it permeates the membrane and how soluble it is in water |
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What class of biopharmaceutics is the best for oral medicines? |
Class 1 (ampiphilic) |
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What is the class of biopharmaceutics which have high permeability and low solubility? |
Class 2 (lipophilic) |
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What is the class of biopharmaceutics which have low permeability and high solubility? |
Class 3 (hydrophilic) |
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How do small molecules generally pass through the lipid bilayer of cells? |
Diffusion |
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How do mid-size molecules generally pass through the lipid bilayer of cells? |
Aqueous channels |
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How do large molecules generally pass through the lipid bilayer of cells? |
Carriers |
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How do the majority of drugs enter cells? |
Bulk transport (passive diffusion) |
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What percentage of marketed drugs contained ionized functional groups? |
85% |
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Can ions pass through plasma membranes? |
Not unless there is a transporter of some sort |
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What is the Henderson-Hasselbalch equation? |
pH = pKa + log( [ionized form]/[non-ionized form]) |
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What is pH trapping? |
Where drug molecules are ionized in either the plasma or cells to prevent them from re-crossing the membrane |
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What are the primary classifications of drug administration? |
Enteral, Topical, Parenteral |
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What are the enteral methods of drug administration? |
Oral, rectal, inhalation |
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What are the topical methods of drug administration? |
Application to epithelial surfaces (e.g. skin, cornea, nasal mucosa) |
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What are the parenteral methods of drug administration? |
Injection (subcutaneous, intravenous, intramuscular) |
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Why are different methods of drug administration used? |
Because they work at different speeds and can target the body systems differently |
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What is bioavailability? |
The fraction of the administered dose which reaches the systemic circulation |
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What factors can affect the rate of absorption for orally administered drugs? |
GI motility, splanchnic blood flow, medicine formulation, drug properties, food, gastric emptying, 1st pass metabolism |
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__% of an orally administered drug is usually absorbed in ____ hours. |
75%; 1-3 hour |
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What can cause incomplete bioavailability in orally administered drugs? |
Incomplete absorption, loss in feces, and 1st pass metabolism |
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Bioavailability is independent of _____. |
Dose |
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What is 1st pass metabolism? |
A property of drug absorption wherein the liver or gut starts metabolizing the drug before it reaches the systemic circulation |
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What does the graph of oral absorption look like? |
'Mountain' shape-- gradual increase to maximum, then decrease |
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What percent of body weight is made up of body water? |
60% |
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That is the volume of distribution? |
The volume of fluid required to contain the total amount of drug in the body at the same concentration that is present in the plams |
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What are the units of Vd? |
Liters |
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What is the minimum value of Vd? |
3 L (volume of intravascular plasma) |
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What are the units for Vd which is normalized to body weight? |
L/kg |
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How is Vd calculated? |
Total amount of drug in the body / blood concentration |
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What does it mean for a drug to have a low (near 3) Vd? |
It is mostly restricted to the plasma or has a high degree of binding to plasma proteins |
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How can Vd be estimated using weight and drug dosage? |
Dosage/(weight*60%) |
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What features impact tissue distribution? |
The size & pKa of the drug molecule, the molecule's binding properties (plasma proteins, etc), blood flow and barriers in the organ or tissue |
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How does obesity affect drug distribution? |
Can decrease distribution as hydrophobic drugs can accumulate in fat tissue |
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What is required for a drug to be therapeutically active? |
It cannot be bound to plasma proteins |
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High blood flow in a tissue correlates to _____. |
High drug distribution |
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What are the two major physiological barriers? |
The blood-brain barrier and placenta |
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Most drugs which penetrate the blood-brain barrier are highly ______. |
Lipophilic |
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Why do antihistamines make you drowsy? |
Because they are highly lipophilic and can penetrate the blood-brain barrier, allowing them to have effects on sleep and concentration |
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What type of drugs can pass readily through the placenta? |
Lipid-soluble drugs |
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How could one calculate bioavailability? |
Comparing the concentration of a drug in the systemic circulation vs. the administered dose |
