Term
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Definition
absorption, distribution, metabolism, and excretion
ADME describes the disposition of a pharmaceutical compound within an organism. |
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Term
| What are the three routes of enteral administration of drugs? |
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Definition
| oral, sublingual/buccal, rectal |
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Term
| What are some examples of parenteral administration? |
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Definition
| subcutaneous, intramuscular, intravenous, intrasynovial, intrathecal, vaginal, urethral, ocular, nasal, aural, intra-peritoneal, epidural |
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Term
| What 6 factors affect drug distribution? |
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Definition
a. regional differences in blood flow
b. tissue mass
c. transport mechanisms
d. permeability characteristics
e. ion-trapping
f. protein binding |
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Term
| What is one-compartment distribution? |
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Definition
| rapid equilibrium is achieved between plasma and tissue distribution following drug administration. plasma concentration-time profile declines mono-exponentially |
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Term
| What is two-compartment distribution? |
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Definition
| rapid distribution to a central compartment followed by a slow distribution to other tissues/binding sites. This results in a bi-exponential plasma concentration-time profile |
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Term
| What 6 things should be considered for the design of a therapeutic regimen? |
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Definition
-dose
-absorption
-first-pass metabolism
-area under the curve (AUC)
-volume of distribution and elimination clearance
-compliance |
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Term
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Definition
F = bioavailability
it is the fraction of an administered dose of unchanged drug that reaches the systemic circulation |
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Term
| What is the bioavailability of a drug administered intravenously? |
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Definition
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Term
| What factors cause bioavailability to be less than 100% through other routes such as oral administration? |
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Definition
| incomplete absorption and first-pass metabolism |
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Term
| What is the equation for clearance of a dose administered intravenous? |
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Definition
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Term
| What is the equation for clearance of a dose administered non-intravenous? |
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Definition
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Term
| How do you calculate oral bioavailability using AUC? |
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Definition
| F(oral) = AUCp.o./AUVi.v. x 100% |
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Term
| How do you calculate oral bioavailability using dosage? |
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Definition
| F(oral) = (Dose i.v.)/(Dose p.o.) x 100% |
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Term
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Definition
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Term
| What is the first-pass effect? |
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Definition
| some drugs have such a high rate of metabolism that none of the dose ever enters the systemic circulation even though it is completely absorbed |
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Term
| What are the advantages and disadvantages of sublingual/buccal drug administration? |
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Definition
advantages:
-will not be absorbed into the portal system and therefore avoids first pass metabolism
-a higher pH than found in the stomach may be beneficial for absorption of more basic drugs
disadvantages:
-drug taste |
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Term
| What are the advantages and disadvantages of rectal drug administration? |
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Definition
advantages:
-50-60% will by-pass the portal vein and avoid first-pass hepatic metabolism
-useful in cases of nausea and vomiting
disadvantages
-discomfort, inconvenience |
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Term
| Where does first pass metabolism mainly occur? |
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Definition
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Term
| when pH = pKa, what percentage of the drug is ionized? |
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Definition
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Term
| if pH is greater than pKa, what percentage of the drug is ionized? |
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Definition
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Term
| What is enterohepatic circulation? |
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Definition
| if drugs are absorbed by the liver and secreted into the bile they may be reabsorbed via the intestine (this could reduce bioavailability) |
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Term
| Why is bioavailability labeled "F"? |
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Definition
| It is the fraction of the absorbed drug that reaches the systemic circulation in its active form |
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Term
| What is the "salt factor" (S)? |
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Definition
| the fraction of total drug that will be delivered as ACTIVE drug to the systemic circulation |
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Term
| How does the equation for loading dose change when there is a salt factor? |
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Definition
| Loading dose = [V(d) X TC]/[F x S] |
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Term
| What is the fastest and most reliable means of achieving a defined blood level of a drug? |
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Definition
| intravenous administration |
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Term
| what is a disadvantage of i.v. administration? |
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Definition
| risk of overdose by "bolus effect" |
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Term
| when is subcutaneous parenteral administration not effective? |
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Definition
| when peripheral circulation is impaired such as in shock |
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Term
| how can the rate of absorption be modified for subcutaneous or intramuscular injections? |
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Definition
| altering blood flow (applying heat or cold) |
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Term
| What plasma protein binds acidic drugs? |
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Definition
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Term
| what plasma protein binds basic drugs? |
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Definition
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Term
| What type of distribution pharmacokinetics do the drugs digoxin, lidocaine and phenytoin display? |
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Definition
| two-compartment distribution |
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Term
| What is the Vd of a drug which passes through cell membranes and is not bound to any tissue constituent or taken up into any particular cells? (ie. it is evenly distributed in TBW) |
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Definition
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Term
| What is the Vd of a drug which passes through capillary membrane but not through cell membranes and is not protein bound or extremely lipid soluble? (ie it distributes into extracellular fluid) |
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Definition
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Term
| What is the Vd of a drug which is tightly bound to plasma protein? (ie it has a Vd equivalent to plasma water) |
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Definition
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Term
| Will an increase in the unbound fraction of total [drug] (eg. hypoalbuminemia) result in an increase or decrease in Vd? |
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Definition
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Term
| How do you estimate V(T)? |
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Definition
V(T) ~= V(TW)
V(TW) = TBW - plasma water
TBW = .6(weight in kg)
plasma water = 4L |
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Term
| What are the two most common tissue reservoirs in patients? |
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Definition
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Term
| what class of drugs occupy about 50% of the binding sites on albumin at therapeutic concentrations, thus can displace other drugs? |
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Definition
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