aminoglycosides Flashcards Preview

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Flashcards in aminoglycosides Deck (42):
1

 Some drugs and aminoglycosides
• As the plasma level is increased above the MIC, the drug kills an increasing proportion of bacteria at a more rapid rate

conc dependent

2


 Any antibiotic, including penicillins and cephalosporins
• Directly related to time above MIC
• Independent of concentration once the MIC is reached

TIME DEPENDENT

3

 Structurally related amino sugars attached by glycosidic linkages

aminoglycosides

4

are aminoglycosides polar or not

polar

5

RoA of aminoglycosides

 Given intramuscularly or intravenously for systemic effects

6

Are aminoglycosides absorbed orally?

no

7

tissue penetration of aminoglycosides (full partial limited)

Limited

8

 Does it readily cross the blood-brain barrier

no

9

 Major mode of excretion

Glomerular filtration

10

 Excretion is directly proportional to ---- clearance

creatinine

11

With normal renal function, elimination half-life is

2-3 h

12

 Peak serum levels
 Measured at

30-60 minutes after administration

13

 Trough serum levels
 Measured when

just before the next dose

14

MoA of AG

 Bactericidal (irreversible) inhibitors of protein synthesis

15

 Penetration of bacterial cell wall is partly dependent on ___________

O2-dependent active transport

16

 Transport is enhanced by ________

cell wall synthesis inhibitors

17

 Bind to _____ AND Interfere with protein synthesis

30S ribosomal unit

18

ag interfere with protein synthesis by

1. Block formation of initiation complex
2. Cause misreading of the code on the mRNA template
3. Inhibit translocation

19

MECHANISMS OF RESISTANCE

 Failure to penetrate into the cell
 Plasmid-mediated formation of inactivating enzymes

20

• Primary mechanism of resistance

Plasmid-mediated formation of inactivating enzymes

21


 Catalyze the acetylation of amine functions
 Transfer of phosphoryl or adenyl groups to the O2 atoms of hydroxyl groups on the aminoglycoside

Group transferases

22

transferases produced by enzyme can inactivate

• Amikacin
• Gentamicin
• Tobramycin
• Not streptomycin
• Netilmicin is less susceptible and is active against more strains of organisms

23

for Serious infections caused by aerobic gram (-) bacteria
• E. coli Enterobacter
• Klebsiella Proteus
• Providencia Pseudomonas
• Serratia

GENTAMICIN, TOBRAMYCIN, and AMIKACIN

24


 Tuberculosis
 Plague
 Tularemia
 Multi-drug-resistant (MDR) strains of M. tb resistant to streptomycin maybe susceptible to amikacin

STREPTOMYCIN

25


 Used topically
 Locally
• In the GIT
• Eliminate bacterial flora

NEOMYCIN

26


 Reserved for serious infections resistant to other aminoglycosides

NETILMICIN

27


 Aminocylitol related to aminoglycosides
 Back-up drug
 Intramuscular as single dose for gonorrhea

SPECTINOMYCIN

28

A. OTOTOXICITY
 Auditory or vestibular damage (or both) maybe irreversible or reversible?

IRREVERSIBLE

29

DRUGS RESPONSIBLE FOR
• Auditory impairment

Amikacin and kanamycin

30

DRUGS RESPONSIBLE FOR
Vestibular dysfunction

Gentamicin and tobramycin

31

OTOTOXICITY Risk is proportionate to the
• High if dosage is not modified in renal dysfunction

plasma levels

32

 Increased with the use of loop diuretics
 Contraindicated in pregnancy

OTOTOXICITY Risk

33

RESPONSIBLE FOR
• Allergic skin reactions like contact dermatitis

Neomycin

34

C.
 Rare
 Curare-like block may occur at high doses

NEUROMUSCULAR BLOCKADE

35

is neuromuscular blockade reversible or irre

reversible

36

neuromuscular blockade causes

respiratory paralysis

37

treatment of neuromuscular blockade

Calcium
Neostigmine

38

treatment of neuromuscular blockade requires

Ventilatory support

39

nephrotoxicity more common in (2)

 Patients concurrently receiving
• Amphotericin B
• Cephalosporins
• Vancomycin
Elderly

40

is nephrotoxicity reversible or irre

rever

41

 Most nephrotoxic drugs

Gentamicin and tobramycin

42

nephrotoxicity is in the form of

acute tubular necrosis

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