PK & PD Flashcards

1
Q

ADME

A

Absorption, Distribution, Metabolism, Elimination

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2
Q

What two factors affect distribution?

A

Lipid solubility
Protein binding

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3
Q

T/F: Penicillin G has good oral absorption

A

False - not absorbed orally

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4
Q

How are potassium pen, procaine pen, and benzathine pen given?

A

Potassium - IV
Procaine - IM
Benzathine - IM

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5
Q

How is amoxiclav given in cats and dogs? Horses?

A

Orally

Not in horses though

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6
Q

Distribution of penicillins

A

Hydrophilic
Confined to plasma/ECF
Minimal protein binding

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7
Q

Penicillins have ________ metabolism

A

Minimal

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8
Q

How are penicillins eliminated?

A

Renal! (A reason that they are really good treatment of choice for urinary infections)

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9
Q

How are cephalexin and cefazolin best absorbed?

A

Cefazolin - IV
Cephalexin - oral (dogs and cats)

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10
Q

Distribution of 1st gen cephalosporins

A

Hydrophilic
Confined to plasma/ECF
Low to moderate protein binding

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11
Q

1st generation cephalosporins have _______ metabolism and are eliminated by the _______

A

Minimal; kidneys

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12
Q

Ceftiofur and cefovecin are not absorbed ______

A

Orally

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13
Q

Cefovecin (Convenia) is given _____

A

SC

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14
Q

How is cefpodoxime proxetil best absorbed? What about this drug improves bioavailability?

A

Oral
Proxetil is a pro-drug - cleaved off in the GIT prior to absorption, prevents early metabolism

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15
Q

Distribution of 3rd gen cephalosporins

A

Hydrophilic
Confined to plasma/ECF
Low to moderate to high protein binding depending on drug

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16
Q

What about cefovecin extends its half-life?

A

High protein binding

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17
Q

What 3rd generation cephalosporin has an active metabolite? Otherwise the other 3rd gens have minimal

A

Ceftiofur (to desfuroylceftiofur)

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18
Q

Elimination of 3rd gens?

A

Renal

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19
Q

In general, b-lactam antibiotics are _________ (choose one: bactericidal or bacteriostatic)

A

Bactericidal

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20
Q

B-lactams are time-dependent antibiotics. What does this mean?

A

Concentrations are greater than MIC of the bacteria for a specified % of dosing interval

(50% in immunocompetent, 80% for g (-), 90% for immunosuppressed)

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21
Q

You have an immunocompromised patient being treated with b-lactams. How does this change your dosing compared to an immunocompetent patient?

A

Decrease dosing interval b/c these drugs are time-dependent

Dosing more frequently will help keep drug concentrations above the MIC for a greater % of the dosing interval

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22
Q

T/F: for time-dependent antibiotics, it is best to increase dose to maintain higher concentrations

A

False - best to decrease dosing interval

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23
Q

T/F: Aminoglycosides are absorbed best orally

A

False - not oral; best IV/IM

24
Q

Distribution of aminoglycosides

A

Hydrophilic
Confined to plasma/ECF
Minimal protein binding

25
Q

Aminoglycosides have minimal metabolism and are eliminated via the _______

A

Kidneys

26
Q

Aminoglycosides: bacteriostatic vs. bactericidal?

A

Bactericidal

27
Q

Aminoglycosides are __________ dependent

A

Concentration - max [ ] (Cmax) 8-10x MIC of the bacteria

28
Q

When considering the nephrotoxic effects of aminoglycosides, what is the most important thing to take into account?

A

Want trough concentrations to be <2ug/mL

29
Q

T/F: in contrast to b-lactams, in order to increase the MIC when using an aminoglycosides, the best method would be to increase the dose.

A

True - Aminoglycosides are concentration dependent, B-lactams are time-dependent (best to decrease dosing interval)

30
Q

Most fluoroquinolones are given orally and have moderate to excellent oral absorption. The only exception is __________, which may be given IV/IM.

A

enrofloxacin

31
Q

Which fluoroquinolone is the most lipophilic?

A

Enrofloxacin

32
Q

T/F: Fluoroquinolones are restricted to the plasma and ECF.

A

False - well distributed, intracellular

33
Q

Which fluoroquinolone has an active metabolite? What is the active metabolite?

A

Enrofloxacin (metabolite is ciprofloxacin)

34
Q

How are fluoroquinolones eliminated?

A

Mostly renal, some liver

Exception: pradofloxacin - only 21% renal

35
Q

Fluoroquinolones are ___________ and __________ dependent

A

Bactericidal
Concentration dependent

36
Q

Doxycycline should never be given ______ in horses

A

IV

Will drop dead

37
Q

Doxycycline and Minocycline have ________ PO absorption in dogs and cats

A

Good

38
Q

How is oxytet typically administered?

A

IV/IM

39
Q

Despite being the most lipophilic of the tetracyclines, doxycycline has some trouble reaching certain sites due to…

A

High protein binding

40
Q

Why might Minocycline be a good choice for treating bacterial cholangitis?

A

Hepatic elimination

41
Q

Tetracyclines are bacteri_____ and _____ dependent

A

-ostatic; concentration

42
Q

What is the benefit of giving potentiated sulfonamides together?

A

Bactericidal when given together; bacteriostatic when given alone

43
Q

Macrolides are baller b/c they are ________ distributed and reach intracellular spaces.

A

WIDELY

44
Q

T/F: Macrolides are widely distributed, reach intracelllular spaces, and cross the BBB.

A

False - everything is true besides crossing the BBB into the CSF

45
Q

Don’t give clindamycin to ….

A

Horses

46
Q

Chloramphenicol distribution…

A

Widely distributed
Intracellular
CSF, eye, etc

47
Q

Macrolides, lincosamides, and phenicols are all ________

A

Bacteriostatic

48
Q

What happens if nitroimidazoles are given IV too quickly?

A

Will accumulate quickly in the CNS and can lead to toxicity

49
Q

What are the two main classes of antibacterial agents that cannot be absorbed orally in small animals?

A

Benzylpenicillins
Aminoglycosides

50
Q

What classes have poor oral absorption in horses?

A

B lactams
Macrolides (adult horses)
Lincosamides

51
Q

Penicillins, cephalosporins, and aminoglycosides are _________, resulting in limited distribution

A

Hydrophilic

52
Q

T/F: Pradofloxacin’s absorption is decreased by food.

A

True

53
Q

Tetracyclines are eliminated by both the liver and kidneys, but some are eliminated more by one organ than the other. How are minocycline, doxycycline, and oxytetracycline eliminated?

A

Mino - mostly hepatic
Doxy - mixed
Oxy - mostly renal

54
Q

Explain why you might choose to use minocycline over doxycycline for CNS infections

A

Both minocycline and doxycycline are highly lipophilic and are well distributed, but doxycycline is more protein bound than minocycline, making it more difficult to get into the CNS

55
Q

T/F: Plasma PK for tetracyclines is not predictive of success for treating IC infections. Explain your reasoning.

A

True - intracellular concentrations are 26x higher than plasma