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[MT 6314] Pharmacology & Toxicology > [3S] Chemotherapeutic Agents > Flashcards

[3S] Chemotherapeutic Agents Flashcards

1
Q

An antimicrobial drug that can eradicate an infection in the absence of host defense mechanisms; kills bacteria

A

Bactericidal

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2
Q

An antimicrobial drug that inhibits antimicrobial growth but requires host defense mechanisms to eradicate the infection; does not kill bacteria

A

Bacteriostatic

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3
Q

Drugs with structures containing a beta-lactam ring: includes the penicillins, cephalosporins and carbapenems. This ring must be intact for antimicrobial action

A

Beta-lactam
antibiotics

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4
Q

Bacterial enzymes (penicillinases, cephalosporinases) that hydrolyze the beta-lactam ring of certain penicillins and cephalosporins

A

Beta-lactamases

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5
Q

Potent inhibitors of some bacterial beta-lactamases used
in combinations to protect hydrolyzable penicillins from
inactivation

A

Beta-lactam inhibitors

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6
Q

Lowest concentration of antimicrobial drug capable of
inhibiting growth of an organism in a defined growth medium

A

Minimal inhibitory concentration
(MIC)

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7
Q

Bacterial cytoplasmic membrane proteins that act as the
initial receptors for penicillins and other beta-lactam
antibiotics

A

Penicillin binding proteins (PBPs)

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8
Q

Chains of polysaccharides and polypeptides that are cross-linked to form the bacterial cell wall

A

Peptidoglycan

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9
Q

More toxic to the invader than to the host; a property of useful antimicrobial drugs

A

Selective toxicity

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10
Q

Bacterial enzymes involved in the cross-linking of linear
peptidoglycan chains, the final step in cell wall synthesis

A

Transpeptidases

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11
Q

First to suggest that a Penicillium mold (now known as (Penicillium chrysogenum) must secrete an antibacterial substance

A

Alexander Fleming

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12
Q

Chemotherapeutic Agents

  1. Production of antibiotic-inactivating enzymes
  2. Changes in the structure of target receptors
  3. Increased efflux via drug transporters
  4. Decreases in the permeability of microbes’ cellular
    membrane to antibiotics
A

Microbial Resistance

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13
Q

Chemotherapeutic Agents

  1. Use of adjunctive agents that can protect against antibiotic
    inactivation
  2. Use of antibiotic combinations
  3. Introduction of new (and often expensive) chemical
    derivatives of established antibiotics
  4. Efforts to avoid indiscriminate use or misuse of antibiotics
A

Strategies

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14
Q

Bacteria

A

Antibacterial

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15
Q

Viruses

A

Antiviral

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16
Q

Fungi

A

Antifungal

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17
Q

Parasites

A

Antiparasitic

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18
Q

Major antibiotics that inhibit cell wall synthesis

A

Penicillins & Cephalosporins

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19
Q

T/F: More than 50 drugs that act as cell wall inhibitors are currently available

A

T

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20
Q

T/F: Not as important as beta-lactam drugs
○ Vancomycin
○ Fosfomycin
○ Bacitracin

A

T

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21
Q

Classification

Derivatives of 6-aminopenicillanic acid
Contains a beta-lactam ring structure
Essential for antibacterial activity

A

Penicillin

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22
Q

MOA

  1. Bactericidal
  2. Prevents bacterial cell wall synthesis by binding to and inhibiting cell wall transpeptidases
  3. Inhibition of transpeptidase enzyme that act to cross-link linear peptidoglycan chains
  4. Activation of autolytic enzymes that cause lesions in the bacterial cell wall
A

Penicillin

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23
Q

Penicillin Classification

Additional chemical substituents that
confer differences in

A
  • Antimicrobial activity
  • Susceptibility to acid and enzymatic hydrolysis
  • Biodisposition
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24
Q

PKINETICS

Vary in resistance to gastric acid
Vary in their oral bioavailability
Polar compounds
Not metabolized extensively

A

Penicillin

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25
Q

Penicillin is excreted unchanged in urine via

A

Glomerular filtration & tubular excretion

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26
Q

Penicillin is inhibited by

A

Probenecid

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27
Q

Penicillin PKINETICS

Partly excreted in bile

A

Ampicillin and Nafcillin

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28
Q

Penicillins

  • Given intramuscularly
  • Long half-lives
  • Drug is released slowly
  • Cross blood-brain barrier when meninges
    are inflamed
A

Procaine and Benzathine Penicillin G

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29
Q

Enzymatic hydrolysis of the beta-lactam ring results in

A

the lost of antibacterial activity

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30
Q

Resistance

○ Penicillinases
○ Formed by most staphylococci and gram (-)
organisms
○ Major mechanism for bacterial resistance

A

Beta-lactamases

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31
Q

Resistance

Inhibitors of this enzymes are used in combination with penicillin to prevent their inactivation

A

○ Clavulanic acid
○ Sulbactam
○ Tazobactam

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32
Q

Resistance

Structural changes in target PBPs:
Methicillin resistance in ________
Penicillin G resistance in _________

A

staphylococci
pneumococci

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33
Q

Penicillin Resistance

T/F: Changes in the porin structure in the outer membrane contribute to resistance by impeding access of penicillin to PBPs. Resistance in some gram (-) rods like P. aeruginosa

A

T

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34
Q

Narrow-spectrum penicillinase-susceptible agents

○ Prototype
○ Parenteral
○ Limited spectrum of activity
○ susceptibility to beta-lactamases

A

PENICILLIN G

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35
Q

Narrow-spectrum penicillinase-susceptible agents

infections caused by
■ Streptococci
■ Meningococci
■ gram (+) bacilli
■ Spirochetes

A

PENICILLIN G

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36
Q

Narrow-spectrum penicillinase-susceptible agents

Penicillin-resistant S. pneumoniae (PRSP) strains

A

PENICILLIN G

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37
Q

Narrow-spectrum penicillinase-susceptible agents

Some strains resistant via production of beta-lactamases
■ S. aureus
■ N. gonorrhoeae

A

PENICILLIN G

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38
Q

Narrow-spectrum penicillinase-susceptible agents

○ drug of choice for syphilis
○ activity against enterococci enhanced by
aminoglycoside

A

PENICILLIN G

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39
Q

Narrow-spectrum penicillinase-susceptible agents

○ Oral
○ Oropharyngeal infections

A

PENICILLIN V

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40
Q

Very-narrow-spectrum penicillinase-resistant agents

Treatment of known or suspected staphylococcal
infections

A

METHICILLIN (prototype), NAFCILLIN, OXACILLIN

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41
Q

Very-narrow-spectrum penicillinase-resistant agents

● Methicillin-resistant S. aureus (MRSA)
● S. epidermidis (MRSE) are resistant to other
members of this subgroup and often to multiple
antimicrobial drugs

A

METHICILLIN (prototype), NAFCILLIN, OXACILLIN

42
Q

Wider spectrum penicillinase-susceptible agents

● Wider spectrum than pen G
● Susceptible to penicillinases
● Uses similar to pen G
○ Enterococci
○ L. monocytogenes
○ E. coli
○ P. mirabilis
○ H. influenzae
○ M. catarrhalis

A

AMPICILLIN and AMOXICILLIN

43
Q

Wider spectrum penicillinase-susceptible agents

● Enhanced activity in combination with inhibitors of
penicillinases
● Synergistic (1+1=3) with aminoglycosides in
enterococcal and listerial infections

A

AMPICILLIN and AMOXICILLIN

44
Q

Wider spectrum penicillinase-susceptible agents

● Activity against gram (-) rods
○ Pseudomonas
○ Enterobacter
○ Some cases of klebsiella species
● Synergistic action with aminoglycoside

A

PIPERACILLIN and TICARCILLIN

45
Q

Wider spectrum penicillinase-susceptible agents

● Susceptible to penicillinases
● Enhanced activity in combination with inhibitors of
penicillinases

A

PIPERACILLIN and TICARCILLIN

46
Q

Penicillin main toxicity

A

allergy

47
Q

can cause neutropenia

A

Nafcillin

48
Q

causes maculopapular rashes

A

Ampicillin

49
Q

causes interstitial nephritis more than other
penicillins

A

Methicillin

50
Q

T/F: Penicillin Toxicity

● Antigenic determinants include degradation products like penicilloic acid
● Complete cross-allergenicity exists

A

T

51
Q

Penicillin Toxicity

● Oral penicillins especially ampicillin
○ Nausea and diarrhea
○ Pseudomembranous colitis
■ Maybe caused by direct irritation or by
overgrowth of gram (+) organisms or yeasts

A

GI Disturbances

52
Q

● Derivatives of 7-aminocephalosporanic acid
● Contain the beta-lactam ring structure

A

CEPHALOSPORINS

53
Q

First generation Cephalosporins

A

● Cephalexin
● Cefazolin
● Cefadroxil
● Cephalotin,
● Cephradine
● Cephapirin
Cephalexin is the prototype

54
Q

2nd generation Cephalosporins

A

● Cefuroxime
● Cefoxitin
● Cefotetan
● cefamandole
Cefuroxime is the prototype

55
Q

3rd generation Cephalosporins

A

● Ceftriaxone
● Cefotaxime
● Cefoperazone
● Ceftazidime
● Cefixime

56
Q

4th generation Cephalosporins

A

Cefepime

57
Q

Pkinetics

● Oral
● Some given parenterally

A

Cephalosporins

58
Q

Cephalosporins with side chains undergo

A

hepatic metabolism

59
Q

Cephalosporins Major elimination is via

A

renal tubular excretion

60
Q

Cephalosporins

Excreted mainly in the bile

A

Cefoperazone and ceftriaxone (3rd generation)

61
Q

Do not enter the CSF when the meninges are
inflamed

A

1st- and 2nd-generation

62
Q

Cephalosporins Resistance

Less susceptible to penicillinases produced by
_________

A

staphylococci

63
Q

Resistance

● Structural differences from penicillin
● Decrease membrane permeability to the drug
● Changes in PBPs
● MRSA are also resistant to this drug

A

Cephalosporins

64
Q

Cephalosporins Resistance

Resistance develops through the production of other
_______

A

beta-lactamases

65
Q

Clinical Uses

● Gram (+) cocci
○ Staphylococci
○ Streptococci
● E. coli
● K. pneumoniae

A

First generation: Cefazolin (IV), cephalexin (oral)

66
Q

Clinical Uses

● Surgical prophylaxis in selected conditions
● Minimal activity
○ Gram (-) cocci
○ Enterococci
○ MRSA
○ Most gram (-) rods

A

First generation

67
Q

Clinical Uses

● Less activity against gram (+)
● Extended coverage for gram (-)
● Marked differences in activity occur among the drug

A

2nd generation

68
Q

Clinical Uses

B. fragilis

A

2nd generation: Cefotetan, cefoxitin

69
Q

Clinical Uses

H. influenzae or M. catarrhalis

A

Cefamandole, cefuroxime, cefaclor

70
Q

Clinical Uses

Increased activity against gram (-) organisms
resistant to other beta-lactam drugs

A

3rd generation: Ceftazidime, cefoperazone, cefotaxime

71
Q

Clinical Uses

Ability to penetrate the blood-brain barrier

A

3rd generation: Ceftazidime, cefoperazone, cefotaxime

Except cefoperazone, cefixime

72
Q

Clinical Uses

● Providencia
● S. marcescens
● Beta-lactamase producing strains
○ H. influenzae
○ Neisseria
● Less active against enterobacter strains that produce
extended-spectrum beta-lactamases

A

3rd generation

73
Q

Clinical Uses

Pseudomonas

A

3rd generation: Cefoperazone, ceftazidime

74
Q

Clinical Uses

○ B. fragilis
○ a & b for serious infection

A

3rd generation: Ceftizoxime

75
Q

Clinical Uses

Drug of choice for gonorrhea

A

3rd generation: Ceftriaxone (IV) and cefixime

76
Q

Clinical Uses

○ Single injection for acute otitis media
○ As effective as 10 days of amoxicillin

A

3rd generation: Ceftriaxone

77
Q

Clinical Uses

○ More resistant to beta-lactamases produced by gram (-) organisms
■ Enterobacter
■ Haemophilus
■ Neisseria
■ Some penicillinase-resistant pneumococci

A

4th generation

78
Q

Clinical Uses

Combines the gram (+) activity of 1st gen and wider
gram (-) spectrum of 3rd gen

A

4th generation

79
Q

Cephalosporins Toxicity

A

Allergy & oth adverse effects

80
Q

Other Beta Lactams Drugs

● Monobactam
● Resistant to beta-lactamases produced by certain gram (-) rods
○ Klebsiella
○ Pseudomonas
○ Serratia

A

Aztreonam

81
Q

Other Beta Lactams Drugs

● No activity against gram (+) and anaerobes
● An inhibitor of cell wall synthesis binding to PBP3
● Synergistic with aminoglycosides
● Given IV
● Eliminated via renal tubular secretion
● Half-life is prolonged in renal failure
● No cross-allergenicity with penicillin

A

Aztreonam

82
Q

Other Beta Lactams Drugs

Adverse effects
○ GI upset with possible superinfection
○ Vertigo
○ Headache
○ Rare hepatotoxicity
○ Skin rash

A

Aztreonam

83
Q

Other Beta Lactams Drugs

● Carbapenems
● Chemically different from penicillins
● Retain the beta-lactam ring
● Low susceptibility to beta-lactamases

A

IMIPENEM, MEROPENEM, AND ERTAPENEM

84
Q

Other Beta Lactams Drugs

● Wide activity against
○ Gram(+) cocci
○ Gram (-) rods
○ Anaerobes
● For pseudomonal infections
○ Combine with aminoglycosides

A

IMIPENEM, MEROPENEM, AND ERTAPENEM

85
Q

Other Beta Lactams Drugs

● Given IV
● Useful for infections caused by organisms resistant to other antibiotics
● Drug of choice for Enterobacter

A

IMIPENEM, MEROPENEM, AND ERTAPENEM

86
Q

Other Beta Lactams Drugs

● Rapidly deactivated by renal
dehydropeptidases I
● Imipenem-cilastatin inhibits
renal dehydropeptidases I,
increases half life, and
inhibits formation of
nephrotoxic metabolites
● Renal excretion

A

IMIPENEM

87
Q

Other Beta Lactams Drugs

● Similar to imipenem
● Not metabolized by
dehydropeptidases
● Renal excretion

A

MEROPENEM

88
Q

Other Beta Lactams Drugs

● Longest half-life among
the carbapenems (4 hours)
● Renal excretion

A

ERTAPENEM

89
Q

Other Beta Lactams Drugs

○ Used in fixed combination with certain hydrolyzable
penicillins
○ Plasmid-encoded beta-lactamases
■ Gonococci
■ Streptococci
■ E. coli
■ H. influenzae

A

BETA-LACTAMASE INHIBITORS: CLAVULANIC ACID, SULBACTAM, and TAZOBACTAM

90
Q

OTHER INHIBITORS OF CELL WALL SYNTHESIS

● Bactericidal glycoprotein
● Binds to the D-Ala-D-Ala terminal of the nascent
peptidoglycan pentapeptide side chain
● Inhibits transglycosylation

A

VANCOMYCIN

91
Q

OTHER INHIBITORS OF CELL WALL SYNTHESIS

● Prevents elongation of peptidoglycan chain ¡ Interferes with cross-linking
● Narrow spectrum of activity

A

VANCOMYCIN

92
Q

OTHER INHIBITORS OF CELL WALL SYNTHESIS

● Drug-resistant gram (+) organisms
○ MRSA
○ Penicillin-resistant pneumococci
○ C. difficile

A

VANCOMYCIN

93
Q

OTHER INHIBITORS OF CELL WALL SYNTHESIS

Due to decreased affinity of the drug to the binding
site
○ Replacement of D-Ala by D-lactate

A

Vancomycin-resistant enterococci (VRE) and
vancomycin-resistant S. aureus (VRSA)

94
Q

OTHER INHIBITORS OF CELL WALL SYNTHESIS

● Not absorbed orally
● Maybe given for bacterial enterocolitis
● When given IV, penetrates most tissues

A

VANCOMYCIN

95
Q

OTHER INHIBITORS OF CELL WALL SYNTHESIS

● Eliminated unchanged in urine
● Dosage modification in patients with renal impairment

A

VANCOMYCIN

96
Q

OTHER INHIBITORS OF CELL WALL SYNTHESIS: VANCOMYCIN

Rapid IV infusion may cause diffuse blushing a syndrome known as

A

Red man syndrome

97
Q

Vancomycin toxic effects

A

○ Chills
○ Fever
○ Phlebitis
○ Ototoxicity
○ Nephrotoxicity

98
Q

OTHER INHIBITORS OF CELL WALL SYNTHESIS

● Antimetabolite inhibitor of cytosolic enolpyruvate
transferase
● Prevents the formation of N- acetylmuramic acid which is essential in peptidoglycan chain formation

A

FOSFOMYCIN

99
Q

OTHER INHIBITORS OF CELL WALL SYNTHESIS

● Resistance occurs via decreased intracellular
accumulation of the drug
● Excreted in the kidney with urinary levels exceeding the MICs for many urinary tract pathogens

A

FOSFOMYCIN

100
Q

OTHER INHIBITORS OF CELL WALL SYNTHESIS

● In a single dose
○ Drug is less effective than the 7-day course of
treatment with fluoroquinolones
● Multiple dosing can result to resistance rapidly
● Diarrhea is common
● Synergistic with beta-lactam and quinolones in specific infections

A

FOSFOMYCIN

101
Q

OTHER INHIBITORS OF CELL WALL SYNTHESIS

● Peptide antibiotic
● Interferes with a late stage in cell wall synthesis in gram
(+) organisms
● Marked toxicity
● Limited to topical use only

A

BACITRACIN

102
Q

OTHER INHIBITORS OF CELL WALL SYNTHESIS

● Antimetabolite
● Blocks the incorporation of D-Ala into the pentapeptide
side chain of the peptidoglycan
● Used only in TB caused by organisms resistant to first-line
antituberculous drugs
● Potentially neurotoxic
○ Tremors
○ Seizure
○ Psychosis

A

CYCLOSERINE

[MT 6314] Pharmacology & Toxicology (20 decks)

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