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Pharmacology > Antiobiotics > Flashcards

Antiobiotics Flashcards

1
Q

What is the mechanism of action for penicillins?

A

interfere w/ formation of peptidogylcan layer. and prevent cross linking of Nam and Nag

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2
Q

What are penicillin binding proteins?

A

they are transpeptidases that bind penicillin, binding activates autolytic enzymes in the cell wall that cause lesions resulting in bacterial death

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3
Q

What are the 4 ways that bacteria become resistant to penicillin?

A
  1. modify their PBPs
  2. Active pumping of drugs back out of the cell
  3. Cleavage of the beta-lactam ring via beta-lactamases
  4. Altered porins (only gram -) if present
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4
Q

What are important drug interactions involved with penicillin?

A
  1. For them to be effective, microorganisms should be actively growing and dividing. So avoid taking w/ bacteriostatic drugs.
  2. may be taken w/ irreversible beta-lactamases inhibitors
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5
Q

What penicillins are used to treat gram negative bacteria?

A

Aminopenicillins and Antipseudomonal

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6
Q

What penicilins are used to treat gram + bacteria?

A

Natural and penicillinase-resistant

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7
Q

What are examples of natural penicillins?

A

Penicillin G and V

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8
Q

How does one take penicillin G?

A

IV or IM b/c destroyed in acidic environment

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9
Q

How does one take penicillin V?

A

Orally but on a empty stomach

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10
Q

What are examples of Aminopenicillins?

A

Ampicillins and amoxcillins

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11
Q

How does one take ampicillin?

A

orally on empty stomach

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12
Q

How does one take amoxcillin?

A

w/ or w/out food

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13
Q

How can aminopenicillins be taken?

A

parenterally or enterally

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14
Q

What are examples of Penicillanse-resistant penicillins?

A

methicillin, oxacillin, and nafcillin, dicloxacillin

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15
Q

Which penicillinase-resistant drugs can bebe taken parenterally?

A

Methicillin, Nafcilin, and Oxacillin (MNOP)

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16
Q

Which penicillinase-resistant drugs can be taking orally?

A

Dicloxacillin

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17
Q

What is the function of cabencillin?

A

used to treat UTIs

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18
Q

What are examples of irreversible beta-lactamase inhibitors?

A

Clavulanic acid, sulbactam, and tazobactam

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19
Q

What is unique about beta-lactamase inhibitors activity?

A

have no activity on their own and need to be combined w/ penicillins for expanded coverage

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20
Q

What are examples of antipseudomonal penicillin drugs?

A

cabencillin, tircarcillin, mezlocillin, piperacillin

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21
Q

How are most antipseduomonal drugs taken? except?

A

parenterally except Cabencilin is taken orally

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22
Q

What is the mechanism of action for penicillinase-resistant drugs?

A

Have a side group that protects the drugs from being inactivated by beta-lactamases

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23
Q

What do cephalosporins resemble?

A

penicillin, possess beta-lactam backbone

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24
Q

Are cephalosporins unstable or stable to pH changes?

A

stable, thus may be taken w/ or w/out food

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25
Q

What are the 6 adverse effects of cephlosporins?

A
  1. Penicillin-allergic patients may also be hypersenitive
  2. GI irritation is common so take w/ food
  3. Parenterally administered can cause local irritation at sire of injection
  4. Renal toxicity possible if excretion problems exist. Avoid giving to patients w/ preexisting renal disease.
  5. Newer ones may cause seizures but usually only concern those w/ impaired kidney causing drug to accumulate
  6. Secondary infections may occur due to disruption of normal flora
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26
Q

What are examples of Carbapenems?

A

imipenem, cilastatin, doripenem, ertapenem, and meropenem

27
Q

What is the mechanism of action for carbapenems?

A

Bactericial, have different stereochemical structure in their Beta-lactam ring that renders them resistant to Beta-lactamases

28
Q

What is the mechanism of action of telavancin and vancomycin?

A

Block polymerization and cross-linking of peptidoglycan by binding to D-Ala terminal pair

29
Q

What additional mechanism of action does telavancin have?

A

disrupts membrane potential and changes in cell permeability

30
Q

What is cycloserine used for?

A

treat TB infections resistant to first line antitubercular drugs

31
Q

What is polymyxin B used to treat?

A

nearly all gram negative except Proteus

32
Q

How does polymyxin B work?

A

cationic detergent disrupts lipoproteins in bacterial cell wall resulting in increased membrane permeability

33
Q

What are aminoglycosides used to treat?

A

mainly gram negative bacteria

34
Q

What are examples of aminoglycosides?

A

amikacin, gentamicin, kanamycin, netilmicin, streptomycin, tobramycin, and neomycin

35
Q

What are the 3 ways that aminoglycosides interfere w/ 30 S ribosomal subunit?

A
  1. formation of initiation complex
  2. Misread mRNA and miscode AA in growing peptide chain
  3. Cause ribosomes to separate from mRNA
36
Q

How are aminoglycosides administered and why?

A

Parenterally b/c really water soluble

37
Q

Where do aminoglycosides accumulate?

A

inner ear and renal cortex leading to nephrotoxicity and orotoxicity

38
Q

what is unique about aminoglycosides’ pharmacokinetics?

A

translational mechanism of action causes microorganisms to continue to die as plasma levels of drug declines – known as postantiobiotic effect

39
Q

How do bacteria resist aminoglycosides?

A
  1. alter receptor proteins on their ribosomes so prevents binding
  2. may enymatically/posttranslationally alter drugs inhibiting efficient binding
40
Q

What are examples of tetracyclines?

A

tetracyclin, minocyclin, doxycyclin, demeclocyclin, oxytetracycline

41
Q

What is the mechanism of action for tetracycline?

A

Bacteriostatic. Reversible binding of 30 S subunit. Prevent binding of new incoming AA and interfere w/ peptide growth

42
Q

What is a 1st glycycline antiobiotic?

A

Tigecycline, It overcomes 2 mechanisms of resistance: efflux pumps and ribosomal protection

43
Q

What is mode of penetration for tetracycline in the two types of bacteria?

A 
negative = passive diffusion
positive = active transport
44
Q

Why is it best to administer tetracyclines on an empty stomach?

A

B/c divalent cation chelators or bile acid resin inhibit gastric absorption

45
Q

Why is it good to use doxycycline?

A

undergoes hepatic metabolism and excreted in feces so safest option in patients w/ renal dysfunction

46
Q

What is the resistance for tetracyclines?

A

Gram positive use efflux pumps

Gram negative alter their outer membrane protein

47
Q

What is the mechanism of action for chloramphenicol?

A

Bacteriostatic

Binds to 50S subunit and block linkage of incoming AA by interfering w/ peptidyl transferase

48
Q

How are chloramphenicols metabolized?

A

In the liver via glucuronidation

49
Q

What are the consequences of using chloramphenicols in patients w/ hepatic disease?

A

Drug accumulates resulting in grey adults/babeis.

Signs: pale/cyanosis, abdominal distention, may die of respiratory or vasomotor collapse

50
Q

What is the common drug for lincosamides?

A

clindamycin

51
Q

How lincosamides work?

A

prevents translocation of incoming AA from ribosomal A site to P site by binding to 50S subunit

52
Q

What are examples of macrolides?

A

erthyromycin bases, estolates, stearates, ethylsuccinates; clarithromycin, acithromycin

53
Q

What is the mechanism of action for macrolides?

A

Bind to 50 S subunit, prevents translocation from site A to site P,
Bacteriostatic or bacteriocidal depending on drug [ ]

54
Q

What other drugs are involved in cross-resistance w/ macrolides?

A

clindamycin and cloramphenicol

55
Q

How do bacteria become resistant to macrolides?

A
  1. permeability is altered
  2. methylate bacterial 50 S subunit
  3. enzymatically destroy the drug
56
Q

What are adverse effects of erythrymycin?

A

Associated w/ GI distress so take w/ food

Inhibit P450 3A4 and can prolong QT interval on ECG

57
Q

What are adverse effects of carithrymycin?

A

Inhibit P450 3A4 and prolong QT interval

58
Q

What are adverse effects of azithromycin?

A

minimal incidence of diarrhea

59
Q

What are adverse effects of estolate salt?

A

May cause cholestatic hepatitis, elevated liver enzymes, malaise, nausea, vomiting, abdominal cramps, jaundince, and fever

60
Q

What is the role of liver function test?

A

to monitor if hepatotoxicity is suspected w/ estolate salts

61
Q

What is the key ketolide?

A

telithromycin - poor substrate for bacterial efflux pumps

62
Q

What is the mechanism of action for ketolides?

A
  1. Inhibit 50 S subunit by binding to 2 separate domains
63
Q

Why is it harder to form resistance to ketolides?

A

2 different mutations are needed to over ketolides mechanism of action

Pharmacology (5 decks)

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