Term
| fraction of drug excreted unchanged in the urine |
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Definition
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Term
| What does a low Fe value mean? |
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Definition
| The drug doesnt significantly depend on the kidneys for clearance |
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Term
| What is the effect of ionization of passive reabsorption? |
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Definition
| unionized/lipophillic molecules are more likely to be reabsorbed |
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Term
| How do diuretics affect renal clearance of drugs that are extensively reabsorbed? |
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Definition
They increase urine flow which wipes out the concentration gradient
Less reabsorption = increase in renal clearance = decrease in plasma concentration |
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|
Term
| most enzymatic pathways convert drugs to more (polar or nonpolar) metabolites? |
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Definition
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Term
| Can liver enzymes be induced or inhibited? |
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Definition
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Term
| What is the maximum amount of liver blood flow (Q)? |
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Definition
|
|
Term
| What does an E of 0 mean? An E of 1? |
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Definition
E = 0 means that there was no first pass metabolism and that the drug is dependent on the kidneys for elimination
E=1 means that the entire drug was metabolized by the liver on the first pass |
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Term
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Definition
| Extraction ratio = Cin-Cout / Cin |
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Term
| What is the primary influence on E? |
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Definition
| intrinsic clearance aka enzyme activity |
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Term
| How does congestive heart failure influence Q? |
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Definition
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Term
| A high E drug is given to a patient with congestive heart failure. How is the clearance affected? How will you adjust infusion rate? |
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Definition
| reduced clearance so need to give a lower infusion rate |
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|
Term
| What are the ranges for Fe? |
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Definition
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Term
| At steady state, conc vs time profile is the same from interval to interval so long as : ___________ and ____________ |
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Definition
| PK parameters of the patient dont change and dose and dosing interval are not changed |
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Term
| How long does it take a drug to reach steady state? |
|
Definition
|
|
Term
|
Definition
| the half life and dosing interval |
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|
Term
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Definition
| Its used to predict the concentration at steady state if you know the concentration after the first dose |
|
|
Term
| what is the maximum acceptable P:T? |
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Definition
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|
Term
|
Definition
| dose rate and total clearance |
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|
Term
| What is P:T influenced by? |
|
Definition
| Kel, dosing interval, Tmax |
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|
Term
rapid release tabs and soln and suspensions have what kind of Tmax values?
What about slow release tabs? |
|
Definition
rapid release have low/short Tmax values
slow release have prolonged Tmax |
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|
Term
| What P:T value is a reasonable goal for most drugs with narrow therapeutic windows? |
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Definition
|
|
Term
| what are the three influences on Css avg? |
|
Definition
| dose rate, bioavailable fraction, total body clearance |
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|
Term
| What is the relationship between rate of elimination and concentration in first order kinetics? |
|
Definition
| they are proportional to each other |
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|
Term
| in first order kinetics, drug clearance is dose (dependent/independent)? |
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Definition
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|
Term
| In first order kinetics, if you double the dose, what happens to plasma conc and AUC? |
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Definition
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|
Term
| In zero order/ non-linear kinetics, CL is dose (dependent/independent)? |
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Definition
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|
Term
| What would a Dose vs AUC graph look like for non linear drugs? |
|
Definition
| First it would increase in a linear fashion and then it would increase exponentially |
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|
Term
| Do PK parameters vary in non linear PK? If so, which. If not, why not? |
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Definition
| Yes, remember that in non-linear PK, clearance will vary. And if clearance varies, then so do half life and Vd (because they are affected by clearance) |
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|
Term
| What percent of phenytoin is protein bound? |
|
Definition
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|
Term
| How is phenytoin eliminated and does it follow zero or first order kinetics? |
|
Definition
| eliminated entirely by hepatic metabolism and follows zero order kinetics |
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|
Term
| What is S? What does an S value of .92 mean? |
|
Definition
S = salt factor
S of .92 means that 92% of the drug is NOT a salt and 8% is in salt form |
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|
Term
| What is the S factor for phenytoin as a cap or injection? As a tablet or suspension? |
|
Definition
cap/injection - 0.92
tab/suspension - 1 |
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|
Term
| nonlinearity most commonly results from ________ at drug conc considered normal in most patients |
|
Definition
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|
Term
| What is an example of a drug that shows saturable solubility? |
|
Definition
|
|
Term
| What is an example of a drug that shows saturable transport? |
|
Definition
| Amoxicillin and riboflavin |
|
|
Term
| For amoxicillin, what happens to Cmax, Tmax and AUC when you increase the dose? |
|
Definition
cmax - decrease
tmax - no change
AUC - decrease |
|
|
Term
| What are three drugs that exhibit saturable protein binding? |
|
Definition
| naproxen, cefazolin, and salicylates |
|
|
Term
| what drugs show saturable tissue binding? |
|
Definition
|
|
Term
| How does cirrhosis and renal disease affect protein binding? |
|
Definition
| protein binding decreases |
|
|
Term
| what does naproxen bind to? |
|
Definition
|
|
Term
| how are Vd and CL affected by increasing the dose of naproxen? |
|
Definition
Increase in Vd with increase in dose
decrease in CL with increase in dose |
|
|
Term
| How are Fut and Vd affected by increase in dose of methotrexate? |
|
Definition
Fut increases significantly
Vd decreases with increasing dose (drug moves from tissues into plasma) |
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|
Term
| What is an example of a drug that shows saturable metabolism? Namely, hepatic clearance |
|
Definition
|
|
Term
| Which drugs show saturable excretion by renal clearance? |
|
Definition
|
|
Term
| What drug alters its own renal excretion |
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Definition
|
|
Term
| what systems in the body are potentially saturable? |
|
Definition
| hepatic metabolism (limited number of enzymes) and rena tubular secretion |
|
|
Term
| what drug shows saturable first pass metabolism? |
|
Definition
|
|
Term
| Which drug is an exception to the rule because its a high E drug but shows saturable kinetics? |
|
Definition
|
|
Term
|
Definition
| max rate of metabolism possible |
|
|
Term
|
Definition
Michaelis constant, concentration at which Vmax is one half og its maximum value.
Its the conc at which enzymes are half saturated |
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|
Term
| High Km drugs exhibit (linear/nonlinear behavior)? |
|
Definition
|
|
Term
| What is a classic example of a low Km drug? |
|
Definition
|
|
Term
| What is a drug that induces its own metabolism? |
|
Definition
|
|
Term
| What drug inhibits its own metabolism? |
|
Definition
|
|
Term
| what is an example of a drug that shows saturable renal excretion? |
|
Definition
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