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Pharm block 2 > Cell wall synthesis inhibitors > Flashcards

Cell wall synthesis inhibitors Flashcards

1
Q

What are the drug classes that are cell wall synthesis inhibitors?

A
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2
Q

What is the mechanism of action for penicillins?

A

interfere with formation of peptidoglycan layer and bacteriocidal

specifically bind to transpeptidase enzyme whose function cross-links NAM and NAG

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3
Q

What are the penicillin binding proteins activated by penicillins?

A

transpeptidases

autolysins

carboxypeptidases/endopeptidases

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4
Q

autolysisn is a penicillin binding protein. how does it work?

A
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5
Q

Carboxypeptidases/endopeptidases are PBPs. How do they work?

A

break peptide bonds

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6
Q

For penicillins to gain access to microbes, they must permeate the cell wall. What mechanisms of resistance do bacteria have for this?

A
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7
Q

Penicillins that are combined with bacteriostatic drugs. What happens?

A

antagonism results

synergistic actions are not expected

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8
Q

For penicillins to be effective inhibitors of cell wall synthesis, what must be taking place?

A

microbe must be actively growing and dividing

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9
Q

How do penicillins inhibit synthesis of bacterial cell walls? and what are the 2 results?

A

binding to penicillin binding proteins

  1. inhibits cell wall synthesis by blocking transpeptidation of peptidoglycan
  2. activates autolytic enzymes in cell wall that cause lesions resulting in bacterial cell death
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10
Q

What mechanism will allow bacteria to become resistant to penicillins?

A

actions of penicillins may be terminated by B-lactamase enzymes that reside in the periplasmic space

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11
Q

What can penicillin be combined with to get syngeristic actions?

A

penicillins + aminoglycosides

combo is a cell wall synthesis inhibitor plus a protein synthesis inhibitor

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12
Q

Why should antibiotics not be taken with oral contraceptives?

A

estrogens are recycled via the enterohepatic recirculation pathway and normally gut bacteria cleave estrogen-glucuronide allowing them to be reabsorbed

with antibioitcs, normal GI flora are disrupted that impairs enterohepatic recirculation of estrogenic compounds thus diminishing their half-life

use a backup for 7 days after finishing dose of antibiotics

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13
Q

What are the 4 distinct subclassifications of penicillins?

A
  1. natural penicillins
  2. aminopenicillins
  3. penicillinase-resistant penicillins
  4. antipseudomonal penicillins
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14
Q

What will coadministering penicillins with drugs that are irreversible inhibitors of B-lactamase do?

A

broaden the spectrum of coverage to include B-lactamase producing organisms

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15
Q

Which classes of penicillins are used to treat gram + microbes?

A

natural penicillins and penicillinase-resistant penicillins

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16
Q

Which classes of penicillins are used to treat gram (-) organisms?

A

aminopenicillins and antipseudomonal penicillins

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17
Q

What are the natural penicillins?

A

penicillin G and V

18
Q

How should penicillin G be administered? why? and what indications are necessary?

A

administered via IV or IM because it is readily destroyed in acidic environments

treats rheumatic fever and syphilis

19
Q

When should penicillin V be administered? How? What indications?

A

it is more stable so can be given orally

should be given on empty stomach, or 1 hour before meals, or 2-3 hours after meals

treats streptococcal pharyngitis

20
Q

What drugs are amino penicillins?

A

ampicillin

amoxicillin

21
Q

How should ampicillin be administered?

amoxicillin?

A

ampicillin can be orally given but best on empty stomach

amoxicilin can be taken w/ or w/o food b/c it is stable in presence of gastric acid

22
Q

What are the penicillinase-resistant penicillins?

A
  • dicloxacillin,
  • methicillin,
  • oxacillin,
  • nafcillin
23
Q

What is the mechanism of action of the penicillinase-resistant penicillins?

A

contain sie groups that protect the drugs from being inactivated by bacterial B-lactamases

24
Q

Describe the different routes of administration for the penicillinase-resistant penicillins

A

methicillin, oxacillin, nafcillin => parenterally

dicloacillin => orally

25
Q

What are the antipseudomonal penicllins (extended-spectrum)?

A
  • carbenicillin
  • ticarcillin
  • mezlocillin
  • piperacillin
26
Q

How are the antipseudomonal penicillins usually administered? are there any exceptions?

A

parenterally

carbenicillin can be administered orally but therapeutic levels are only found in urinary tract

27
Q

Carbenicillin is an antipseudomonal penicillin. What indications provide use for this?

A

urinary tract and prostatic infections

28
Q

What are the irreversible inhibitors of B-lactamases?

A

clavulanic acid

sulbactam

tazobactam

29
Q

what is important about the administration of the irreversible B-lactamase inhibitors?

A

they have NO antimicrobial activity by themselves

muse be combined with penicillins, expanded coverage against B-lactamase-producing microbes provided

30
Q

Describe the cephalosporins structure and when they should be taken and how

A

cephalosporins resemble penicillins

they possess a B-lactam backbone

unlike natural penicillins, they are stable to pH changes and may be taken w/ or w/o food

31
Q

If a patient has a penicllin allergy, would you prescribe cephalosporins?

A

no => possibility that penicillin-allergic patients may also be hypersensitive to cephalosporins

32
Q

When cephalosporins are given orally, what is an adverse side effect? what if parenterally?

A

orally=> GI irritation but if taken with food then can be prevented

parenterally=> local irritation at site of injection

33
Q

WRT excretion, what adverse effect of cephalosporins should be monitored?

A

since many are excreted by kidneys, renal toxicity is possible

caution for pre-existing renal disease or impaired creatinine clearance

34
Q

2nd and 3rd generation cephalosporins may cause what adverse side effects? what if they are given parenterally?

A

disulfiram-like reactions and hyprothrombinemia

parenterally=> may cause seizures especially those with impaired kidney function due to accumulation

35
Q

Cephalosporins disrupt normal flora. What is an adverse effect of this?

A

secondary infections

pseudomembrnaous colitis

vaginal yeast infections

36
Q

What are the drugs considered carbapenums?

A

imipenem/cilastatin,

doripenem,

ertapenem

meropenem

37
Q

What is the mechanism of action for the carbapenems? what is there structure and how does this help them?

A

bactericidial and inhibit cell wall synthesis

different stereochemical structure in B-lactam ring that renders them resistant to B-lactamases

38
Q

What are some other antibiotics that dirupt cell walls?

A
  • telavancin
  • vancomycin
  • cycloserine
  • polymyxin B
39
Q

What is the general mechanism of action for tevavancin and vancomycin?

A

interfere with cell wall synthesis by blocking polymerization and cross-linking of peptidoglycan by binding to D-Ala-D-Ala portion of cell wall

40
Q

along with blocking polymerization and cross-linking of peptidoglycan by binding to D-Ala-D-Ala portion of the cell wall, what is the other mechanism in which televancin work?

A

disruption of membrane potential and changes in cell permeability because of presence of lipophilic side chain moiety

41
Q

What is the mechanism of action for cycloserine? What organisms does it work for? What is it mainly used for?

A

inhibits cell wall synthesis in gram (+) and gram (-) microbes

reserved usually for treating Mycobacterium tuberculosis that are resistant to 1st-line antitubercular drugs

42
Q

What is the mechanism of action for polymyxin B? What does it fight well?

A

cationic detergent that disrupts lipoproteins in bacterial cell walls to increase the membrane permeability

bactericidal to nearly all gram (-) bacilli (except proteus)

Pharm block 2 (12 decks)

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