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OPath Block 2 > 10. Inhibitors of Cell Wall Synthesis > Flashcards

10. Inhibitors of Cell Wall Synthesis Flashcards

1
Q

What are four inhibitors of cell wall synthesis drugs?

A

Penicillins

Cephalosporins

Vancomycin

Bacitracin

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2
Q

Who discovered penicillin? When?

A

Alexander Fleming in 1928

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3
Q

What was the mold Fleming used to fiht bacteria and agaist which bacteria?

A

Penicillium notalum was isolated to fight staphylococci

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4
Q

What is penicillin’s mechanism of action?

A
  • Bactericidal
  • Interferes with last step (transpeptidase) of bacterial cell wall synthesis, causing cell lysis
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5
Q

What kind of bacteria is penicillin effective against?

A

Rapidly growing organisms that synthesize peptidoglycan cell wall

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6
Q

Describe the two major steps of peptidoglycan cell wall synthesis

A
  • Synthesis of peptidoglycan in single chains
    • occurs in cytoplasmic side of cell membrane
  • Polymerization and cross linking of single chain peptidoglycan
    • polymerization occurs at cell surface
    • transpeptidase used in this step to polymerize single units
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7
Q

What are the components of penicillin’s basic structure?

A
  1. Thiazolidine ring
  2. beta-Lactam ring
  3. Side chain (R group)
    • R group variation results in different penicillins
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8
Q

What confers bacterial resistance against penicillin?

A
  • Contain beta-penicillinase or acid that cleaves beta-lactam ring
    • hydrolyzes cyclic amide bond of beta-lactam ring
    • usually acquired by transfer of plasmids R
  • Decreased permeability to drug
  • Altered penicillin binding proteins (PBP)
    • PBPs are enzymes involved in forming cross linkages between peptidoglycans
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9
Q

What is the antibacterial spectrum of penicillins?

A
  • Natural penicillins
  • Extended spectrum penicillins
  • Antistaphylococcal penicillins
  • Antipseudomonal penicillins
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10
Q

What are two examples of natural penicillins?

A

Penicillin G

Penicillin V

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11
Q

What are two examples of extended spectrum penicillins?

A

Ampicillin

Amoxicillin

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12
Q

What are two examples of antipseudomonal spectrum penicillins

A

Carbenicillin

Ticarcillin

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13
Q
A
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14
Q

What is the function of beta-lactamase inhibitors?

A

Allows penicillin efficacy in drugs that have developed penicillin resistance via B-lactamase

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15
Q

What are two beta-lactamase inhibitors?

A

Clauvulanic acid (product of Steptomyces clavuligerus)

Sulbactam

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16
Q

What is the mechanism of becta-lactamase inhibitors?

A

Irreversibly binds beta-Lactamase and inactivates them

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17
Q

What are 3 formulations of beta-lactamase inhibitors?

A

Augmentin

Timentin

Unasyn

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18
Q

Components of augmentin

A

amoxicillin + clavulanic acid

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19
Q

Components of timentin

A

ticarillin + clavulanic acid

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20
Q

Components of unasyn

A

ampicillin + sulbactam

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21
Q

How do beta-lactamase inhibitors effect the efficacy of penicillins?

A

Improves efficacy

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22
Q

How are penicillins administered?

A

Oral

IV

IM

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23
Q

Which penicillin is absorbed very well?

A

Amoxicillin

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24
Q

Which penicillins are difficult to absorb?

A

Pen G and Ampicillin bc their absorption are impeded by food

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25
Q

Can Pen cross the placenta?

A

Yes

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26
Q

Does Pen hihgly penetrate the bone and CSF?

A

NO, minimal penetration

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27
Q

How does kinetics of IM administration of Pen compare ot kinetics of orally administered Pen?

A

Reach very high blood levels in comparison to oral

28
Q

Is Pen highly metabolized?

A

No, minimally

29
Q

How is Pen excreted?

A

Kidney

30
Q

What drug if taken with Pen can inhibit Pen excretion?

A

Probenecid inhibits Pen excretion

Probenecid treat gouty arthritis

31
Q

What are adverse reactions of Pen?

A
  • Hypersensitivity
  • Diarrhea
  • Nephritis
  • Neurotoxicity
  • PLT dysfunction
  • Cation toxicity
32
Q

How does Pen cause hypersensitivity?

A
  • Penicilloic acid isa hapten for immune rxn
  • Urticaria/angioedema to anaphylaxis
  • beta-lactam cross reactivity
33
Q

How does Pen cause diarrhea?

A

disrupt normla flora composition

34
Q

How does cation toxicity arise in Pen use?

A
  • K+ and Na+ levels are augmented bc of disruption of their retention
  • disruption of Na and K levels result in cardiac side effects
35
Q

What occurs in acute allergic reactions (< 30mins) to Pen?

A
  • Urticaria
  • Angioedema
  • Bronchoconstriction
  • Shock
36
Q

What occurs in accelerated (30 mins - 48 hrs) allergic reactions from Pen?

A

Urticaria

Pruritis

Wheezing

Mild laryngeal edema

Local inflammatory rxns

37
Q

What occurs in delayed (< 2 days) allergic rxns to Pen?

A

Skin Rash

Oral glossitis

Furred tongue

Black and brown tongue

Cheilosis

Severe stomatitis with loss of buccal mucosa

38
Q

Tx for mild allergic rxn to Pen

A

Benadryl 25-50 mg IV/IM/PO

39
Q

Tx for severe allergic rxn to Pen

A

Epinephrine .03-.05 mg

40
Q

How to determine if pt has allergy to Pen?

A

Skin test with benzylpenicilloyl-polylysine

41
Q

What is the dental use of Pen V?

A

Most frequently used for infection of dental origin

42
Q

What is the dental use of amoxicillin?

A

Superior pharmacokinetics

Periodontal infectoin associated with Gram + or Gram - aerobic and anaerobic microorganisms

43
Q

What is the dental use of Pen G (parenteral)?

A

Reserved for severe infections

44
Q

Pharmacokinetics of Pen:

A: ?

D: ?

M: ?

E: ?

A

A: Oral and parenteral

D: Variable; No CNS entry except with meningitis

M: Minimal

E: Filtratation and excretion: short half life (1-2 hrs)

45
Q

How was Cephalosporins discovered?

A

Cephalosporium acremonium was first isolated in 1948 from sea near sewer outlet off Sardinian coast

46
Q

How does Cephalosporin structure compare to Pen?

A

Very similar in structure and function but have a dihydrothiazine ring instead of a thiazdolidine ring

47
Q

How does Cephalosporin resistance to beta-lactamase compare to Pen?

A

More resistant to beta-lactamase but still susceptible

48
Q

How are semi-synthetic cephalosporins synthesized?

A

Synthesized by adding different chemical groups at R1 and R2 to make different varieties of cephalosporins

49
Q

How have subsequent generations of cephalosporin changed in comparison to previous generations?

A

Subsequent generations has increased Gram - bacterial susceptibility, increased beta-lactamase resistance and decreased efficacy against Gram +

50
Q

What are the 3 categories of cephalosporins antibacterial spectrum?

A

1st generation

2nd genertaion

3rd genertaion

51
Q

What are the two first genertaion cephalosporins drug and their use?

A

Cefazolin

Cephalexin

Used for endocarditis

52
Q

What are two 2nd genertaion cephalosporin drugs?

A

Cefaclor

Cefoxitin

53
Q

What is a 3rd genertaion cephalosporin drug and its use?

A

Ceftriaxone

Used for endocarditis

54
Q

How has the CNS penetration trend changed with each subsequent cephalosporin generation?

A

Increased CNS penetration

55
Q

How is cefazolin administered?

A

Parenteral

56
Q

How is Cephalexin administered?

A

Oral

57
Q

how od cephalosporins distribute in the body?

A

Distribute well thorug body fluids

Only 3rd generation Cephalosporins distribute well into the CSF

58
Q

How are cephalosporins excreted?

A

Renal elimination

59
Q

Which cephalosporins are not excreted renally? How are they elminated?

A

Cefoperazone & Ceftriaxone

Exreted through bile and feces

60
Q

What is the limitation in the dental use of Cephalosporins?

A

Good activity against many orofacial pathogen but limited agfainst oral anaerobes

61
Q

What cephalosporins drugs are used against odontogenic infections? Administration?

A

Orally active first or second generation Cephalosporins

62
Q

Which Cephalosporin drugs are used for bacterial endocarditis prophylaxis?

A

Cephalexin

Cefazolin

63
Q

What are the adverse effects of Cephalosporins?

A

Allergy

Disulfram-like effect

Bleeding

Renal, hepatic dysfunction

64
Q

What is the rate of allergy cross sensitivity b/t cephalosporins and Pen?

A

15%

65
Q

What is cephalosporins disulfram like effect?

A

When taken with alcohol, will cause aldehyde accumulation

Results in respiratory difficulty, nausea and HTN

66
Q

Why do Cephalosporins cause bleeding?

A

Anti-Vit K effect

67
Q

Cephalosporins Pharmacokinetics Summary

  • A: ?
  • D: ?
  • M: ?
  • E: ?
  • T: ?
A
  • A: Oral and parenteral
  • D: Wide; 3rd gen penetrates into CSF
  • M: Not extnesively
  • E: Renal filtration; 3rd gen by bile/feces
  • T: Relatively non-toxic (like Pens);
    • Hypersensitivity leads to proximal renal tubular necrosis
    • Disulfram like toxicity

OPath Block 2 (10 decks)

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