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Pharmacology > 43 Betalactams > Flashcards

43 Betalactams Flashcards

1
Q

Structure of penicillin

A

Thiazolidine ring is attached to a B-lactam ring that carries a secondary amino group (RNH-)

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2
Q

What enzymes hydrolyses the B-lactam ring

A

Bacterial B-lactamases

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3
Q

Hydrolysis of the B-lactam ring by bacterial B-lactamases yiels??

A

Penicilloic acid , which lacks antibaterial activity

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4
Q

3 groups of penicillin

A

Penicillins
Antistaphylococcal penicillins
Extended-spectrum penicillin

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5
Q

These penicillin are resistant to staphylococcal B-lactamases

A

Antistaphylococcal penicilins

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6
Q

These type of penicillin retain the antibacterial spectrum of penicillin and have improved activity against gram-negative rods

A

Extended-spectrum penicillins

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7
Q

Penicillins that can be taken orally and they are stable to gastric acid which makes them suitable for oral administration

A

Penicillin V
Dicloxacillin
Amoxicillin

Amoxicillin/potassium clavulanate
Cloxacillin

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8
Q

Penicillins have greatest activity against?

A

Gram-positive organism
Gram negative cocci
Non B-lactamase producing anaerobes

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9
Q

Penicillins have little activity against?

A

Gram negative rods

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10
Q

Anti-staphylococcal Penicillins are active against?

A

Staphylococci and streptococci

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11
Q

Anti-staphylococcal Penicillins are not active against?

A

Enterococci
Anaerobic bacteria
Gram-negative cocci and rods

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12
Q

Extended-spectrum penicillins have improved activity against?

A

Gram-negative rods

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13
Q

All groups of penicillins are susceptible to hydrolysis by?

A

B-lactamases

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14
Q

MOA of penicillins , all B-lactam antibiotics

A

Covalently binds to the active site of PBP which inhibits transpeptidation reaction and halts peptidoglycan synthesis, and the cell dies

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15
Q

Cell wall if bacteria is composed of?

A

A complex, cross-inked polymer of polysaccharides and peptides known as PEPTIDOGLYCAN

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16
Q

The polysaccharides contains what alternating amino sugars?

A

N-acetylglucosamine and N-acetylmuramic acid.

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17
Q

Where does the five amino acid peptide is linked to?

A

To the N-acetylmuramic acid sugar

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18
Q

Where does the peptide of peptidoglycan terminates in?

A

In D-alanyl-D-alanine

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19
Q

Purpose of cross-links

A

Gives the cell wall its rigidity

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20
Q

An enzyme that removes the terminal alanine in the process of forming a cross-link with a nearby peptide

A

Penicillin-binding protein

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21
Q

Purpose of bacterial cell wall

A

Maintains cell integrity and prevents cell lysis from high osmotic pressure

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22
Q

When does beta-lactam antibiotics kills the bacteria?

A

When they are ONLY actively growing and synthesizing sell wall

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23
Q

4 general mechanism of bacterial resistance

A
  1. Inactivation of antibiotic by B-lactamase
  2. Modification of target PBP
  3. Impaired penetration
  4. Antibiotic efflux
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24
Q

The most common mechanism of resistance

A

Beta-lactamase production

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25
Q

What bacterial produces AmpC B-lactamases

A

Pseudomonas aeruginosa and enterobacter sp and extended-spectrum B-lactamases

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26
Q

AmpC B-lactamases hydrolyze what kinds of drug?

A

Cephalosporins and penicillins

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27
Q

Carbapenems are highly resistant to hydrlysis to what enzyme?

A

Penicillinases and cephalosporinases

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28
Q

Carbapenems are hydrolyzed by what enzyme?

A

Metallo-B-lactamases and carbapenemases

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29
Q

In what type of bacteria causes impaired penetration?

A

Only in gram-negative species because of the impermeable outer membrane of their cell wall

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30
Q

In what membrane protein channel does beta-lactam antibiotics cross from the outer membrane into the inner membrane of gram-negative organism

A

Porins

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31
Q

Absence of porins or down regulation causes?

A

Causes impaired penetration which can greatly impair drug entry into the cell

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32
Q

Among all oral penicillins, what drug is not impaired by food

A

Amoxicillin

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33
Q

What is the most preferred route of administration in penicillin G?

A

Intravenous administration

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34
Q

At least how many hours should you take oral penicillin before or after a meal

A

1-2 hours before of after a meal

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35
Q

Other areas of the body where penicillin is excreted

A

Excreted into sputum and breast milk

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36
Q

Penicillin is rapidly excreted by?

A

Kidneys

Tubular secretion - 90% of renal excretion
Glomerular filtration - 10%

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37
Q

HL of penicillin G

A

30 mins

In renal failure = 10hrs

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38
Q

HL of ampicllin and extended-spectrum penicillin

A

1hr. (Slower than penicillin G)

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39
Q

Primarily excretion of nafcillin

A

Biliary excretion

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40
Q

Where does oxacillin, dicloxacillin and cloxacillin are secreted or eliminated?

A

The kidneys and biliary excretion

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41
Q

An oral drug of penicillin that can be given without meals

A

Amoxicillin

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42
Q

A drug of choice for infections such as:
streptococci
gram-positive organisms
non-B-lactamase producing anaerobes
gram-negative anaerobic organisms

A

Penicillin G

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43
Q

Route of administration of penicillin G

A

IV

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44
Q

oral form of penicilin

A

Penicillin V

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45
Q

. A drug that is effective in treating B-hemolytic streptococcal pharyngitis

A

Benzathine penicillin

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46
Q

Intramuscularly, this is Effective in th treatment of syphilis

A

Benzathine penicillin G

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47
Q

Dicloxacillin, given orally is suitable for treatment of mild to moderate ____ infections

A

Localized staphyloccal

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48
Q

The first antstaphylococcal penicillin that is no longer used due to high rates of adverse effects

A

Methicillin

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49
Q

What drugs should you give in serious staphylococcal infections such as endocarditis

A

Oxacillin and nafcillin

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50
Q

Why is extended spectrum penicillins have greater activity against penicillin against gram0negative bacteria

A

Because of their enhanced ability to penetrate the gram-negative outer membrane

They are also inactivated by B-lactamases

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51
Q

An extended spectrum penicillin that is given orally to treat and lower respiratory tract infections

A

Amoxicillin

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52
Q

Extended spectrum penicilllins that are the most active oral B-lactam antibiotic against pneumococci

A

Ampicillin and amoxicillin

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53
Q

Extended-spectrum penicillin that is effective for shigellosis

A

Ampicilin

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54
Q

An extended-spectrum penicillin that is no longer used for empirical therapy of UTI and typhoid fever

A

Ampicillin

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55
Q

Two class of aminopenicilins

A

Amoxicillin and ampicillin

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56
Q

Classes of carboxypenicillins

A

Carbenicillin and ticarcilin

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57
Q

A drug that is only availale as a co-formulation with the B-lactamase inhibitor tazobactam

A

Piperacillin

58
Q

B-lactamase inhibitors that can be combined with amoxicillin, ampicillin, piperacillin and ticarcillin

A

Clavulanic acid, sulbactam or tazobactam

59
Q

Serious advse effects of penicillins

A

Hypersensitivity

60
Q

How to evaluate patients if they have type 1 hypersnsitivity

A

By Skin testing

61
Q

An antibiotic drug that is similar to penicillin but are more stable to many B-lactamases and have a broader spectrum of activity

A

Cephalosporins

62
Q

What can hydrolyse most cephalosporins

A

Strains of E coli and klabsiella sp expressing extended-spectrum B-lactamases

63
Q

Cephalosporin Drugs that are very active against gram positive cocci such as streptococci and staphylococci

A

First-generation cehalosporins

Cefazolin, cefadroxil, cephalexin

64
Q

Widely used first gen cephalosporins in the USA

A

Cephalexin

65
Q

Excretion of cephalexin is mainly by?

A

Glomerular filtration and tubular secretion into the urine.

66
Q

Drugs that block tubular secretion

A

Probenecid

67
Q

The only first-generation parenteral cephalosporin still in generaluse

A

Cefazolin

68
Q

Route of administration of cefazolin

A

IV or intramuscularly

69
Q

Excretion of cefazolin

A

Kidney (dose adjustment req for renal impaired function)

70
Q

A drug of choice for surgical prophylaxis

A

Cefazolin

71
Q

Cephalosporins that are relatively active against organisms inhibited by first-generation drugs

A

Second-generation cephalosporins

72
Q

Examples of 2nd generation cephalosporins

A

Cefoxitin
Cefotetan
Cefuroxime

73
Q

The three 2nd generation cephalosporins that are available in the USA

A

Cefactor
Cefuroxime
Cefprozil

74
Q

Second generation cephalosporins should not be used in treating what infection?

A

Enterobacter infection (due to resistant mutants expressive a chromosomal B-lactamase that hydrolyze these compounds)

75
Q

The most commonly used oral cephalosporin in the USA

A

Cefuroxime axetil

76
Q

What is the preferred parental route of second generation cephalosporin? Is it IV or IM?

A

IV because IM is painful and should be avoided

77
Q

Second generation drug that has an improved activity against pneumococcus and H influenzae

A

Cefuroxime

78
Q

Oral, first generation drug used for treating skin and soft tssue infections and UTI

A

Cephalexin

79
Q

A third generation cephalosporin that is the only agent with useful activity against psuedomonas aeruginosa

A

Ceftazidime

80
Q

What hydrolyzes 2nd and 3rd gen cephalosporins

A

AmpC B-lactamases

81
Q

HL of ceftriaxone

A

7-8 hours
Can be injected once every 24 hrs in dosage of 15-50 mg/kg/d

82
Q

Two dosage recommendation for ceftriaxone

A

IF:
2g every 12hours - treatment of meningitis
2g every 24hours - treatment for endocarditis

83
Q

HL of third gen cephalosporins

A

1 - 1.7 (except for ceftriaxone)

84
Q

Regimen of choice for treating most gonococcal infections

A

IM ceftriaxone with azithromycin

85
Q

Excretion of ceftriaxone

A

Biliary tract (no dose adjustment)

86
Q

Where do the third gen cephalosporins are secreted?

A

Kidney(dose adj) except for ceftriaxone which is excreted in the biliary tract

87
Q

Approved treatment for meningitis

A

Ceftriaxone and cefoxamine

88
Q

The only available fourth generation cephalosporin

A

Cefepime

89
Q

4th gen cehalosporins are resistant to hydrolysis by?

A

Chromosonal B-lactamases

90
Q

4th gen cephalosporins are hydrolyzed by?

A

Extended-spectrum B-lactamases

91
Q

Cefepime is cleared by the?

HL of cefepime?

A

Kidneys

2hours

92
Q

Useful in the treatment of enterobacter infections

A

Cefepime (4th gen)

93
Q

Cefepime is commonly used empirically in patients presenting with?

A

Febrile neutropenia

94
Q

Prodrug of the active metabolite ceftaroline, first drug to be approved for clinical use in the USA

A

Ceftaroline fosamil

95
Q

Reason why ceftaroline is effective against methicillin resistant staphylococci

A

Has increased binding to PBP2a, which mediates methicillin resistance in staphylococci

96
Q

Ceftaroline is not active against

A

AmpC or extended spectrum B-lactamase producing organism

97
Q

A cephalosporin that is active against methicillin resistant staphylococci

A

Ceftaroline

98
Q

HL and excretion of ceftaroline

A

2.7 HL - excreted renally (dose adj)

99
Q

A cephalosporin combined with B-lactamase inhibitors that is FDA-approved for the treatment of complicated intra-abdominal infections and UTI

A

Ceftolozane-tazobactam
And
Ceftazidime-avibactam

100
Q

HL of ceftolozane-tazobactam and ceftazidime-avibactam and excretion

A

2-3hrs - excreted renally (does adj)

101
Q

Adverse effect of cephalosporins

A

Hypersensitivity reactions:
Allergy, anaphylaxis

102
Q

Patients with a history of anaphylaxis to penicillins should not receive what kind of cephalosporin

A

First or second
While
Third and fourth - administered with caution

103
Q

Adverse effect of cephalosporin in
IM
IV

A

IM - local irritation
IV - thrombophlebitis

104
Q

Cephalosporins that contain a methylthiotetrazole group may cause???

A

Hypoprothrombinemia and bleeding disorder

105
Q

the only methylthiotetrazole-containing agent used in the USA

A

Cefotatan

106
Q

What medicine to take in order to prevent hypoprothrombinemia and bleeding disorders in patients taking cephalosporins that contain a methylthiotetrazole group?

A

PO of vitamin K. 10mg twice weekly

107
Q

Drugs with a monocylclic B-lactam ring

A

Monobactams

108
Q

The only monobactam available in the USA

A

Aztreonam

109
Q

Monobactams spectrum of activity is limited only to?

A

Aerobic gram-negative organisms ( P aeruginosa )

Wala slay activity sa gram + or anaerobes

110
Q

Monobactams are stable to what B-lactamases

A

AmpC B-lactamases and extended spectrum B-lactamases

111
Q

Does aztreonam crosses the BBB?

A

Yes

112
Q

Route of administration of aztreonam

A

IV every 8hrs, 1-2g dose

113
Q

Patient with history of penicillin anaphylaxis should be treated with ?

A

Aztreonam and not with 1,2,3,4th gen cephalosporins

114
Q

Traditional B-lactamase inhibitors, resembles B-lactam molecule

A

Clavulanic acid, sulbactam, tazobactam

115
Q

B-lactamase inhibitors are available only in fixed combinations with specific what drug?

A

Penicillins and cephalosporins

116
Q

The first drug of class in carbapenems

A

Imipenem

117
Q

Has a wide spectrim with good activity against most gram-negative rods, gram0positive organisms and anaerobes

A

Imipenem ( carbapenems )

118
Q

What inactivates imipenem and where is it inactivated

A

Dehydropeptidases in renal tuules

119
Q

Inhibitor or renal dehydropeptidase

A

Cilastatin

120
Q

Route of administration, g given nd HL of imipenem

A

IV
0.25g - 0.5g every 6-8hrs
1hr HL

121
Q

A carbapenem that is not degraded by renal dehydropeptidase

A

Ertapenem

122
Q

The longest HL of a carbapenem

A

Ertapenem ( 4 hrs )

123
Q

Carbapenems are highly active against

A

Treatment of enterobacter infections (they are resistant o destruction by the B-lactamase produced by these organims)

124
Q

Most common adverse effect og carbapenem

A

Imipenem - nausea, vomiting, diarrhea, skin rashes

125
Q

An antibiotic isolated from the bacterium now known as amycolatopsis orientalis

A

Vancomycin

126
Q

Antibioticc isolated bacterium

A

Amycolatopsis orientalis

127
Q

Antiobiotic that is active primarily against gram positive bacteria due to its large molecular weight and lack of penetration through gram-negative cell membranes

A

Vancomycin

128
Q

MOA of vancomycin

A

Inhibits cell wall synthesis by binding to the D-Ala-D-Ala terminus which inhibits the transglycosylase, preventing elongation of peptidoglycan and cross linking.

129
Q

Resistance to vancomycin in enterococci is due to?

A

Modification of D-Ala-D-Ala binding site in which the terminal D-Ala is replace with D-lactate.

130
Q

Vancomycin is bactericidal for gram-positive bacteria in concentrations of?

A

0.5-10 mcg/ml

131
Q

Vancomycin is active against manny gram-positive anaerobes including?

A

C difficile

132
Q

PO vancomycin is a treatment against?

A

Colitis caused by C difficile

133
Q

This drug is widely distributed in the body including adipose tissue.

A

Vancomycin

134
Q

90% of vancomycin is exrcreted by?

A

Glomerular filtration

135
Q

Parenteral vancomycin treats?

A

Infections and endocarditis caused by methicillin-resistant staphylococci

136
Q

Vancomycin in combination with gentamicin treats

A

Enterococcal endocarditis

137
Q

Vancomycin in combinations with cefotaxime, ceftriaxone or rifampin treats?

A

Meningitis

138
Q

Used as a first line treatment for C difficile colitis

A

Oral vancomycin

139
Q

Common adverse effects of vancomycin

A

“Red man” syndrome

140
Q

A glycopeptide antibiotic that is very similar to vancomycin but its difference is that, this drug can be given intramuscularly

A

Teicoplanin

141
Q

How to prevent red man syndrome

A

Treat with antihistamine such as diphenhydramine

Bc this syndrome released histamine

142
Q

A semisynthetic lipoglycopeptide derived from vancomycin

A

Telavancin

Pharmacology (15 decks)

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