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Pharmacology > Protein Synthesis Inhibitors > Flashcards

Protein Synthesis Inhibitors Flashcards

1
Q

What do Protein Synthesis inhibitors target?

A

the ribosome that synthesizes the protein from the mRNA code

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2
Q

What is the Bacterial ribosome unit?

A

50S and 30S

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3
Q

What is the Mammalian ribosome unit?

A

60S and 40S

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4
Q

Which are the Amninoglycosides

A

GANS
Gentamycin
Amikacin
Neomycin: tropical ONLY
Streptomycin

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5
Q

Spectrum of Aminoglycosides

A

Bactericidal
Aerobic gram -ive infections: narrow
Some gram _ive infections
Myobacterial Infections
DOC: Pseudomonas Aeruginosa

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6
Q

Topical admin of Aminoglycosides are for

A

serious sight-threatening eye infections, Otitis media, infection of nasal vestibuli
*not recommended for skin infections

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7
Q

How are Aminoglycosides used for Anaerobic gram +ive infections

A

co-admin with Metronidazole or Clindamycin

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8
Q

How are Aminoglycosides used synergistically

A

with Penicillins against serious infections caused by:
Satphylococci
Streptococci
Enterococcci

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9
Q

How do Aminoglycosides enter the cell?

A

Penetrate across the outer membrane via the porins via passive diffusion
-> actively transported across bacterial cell membrane into cytoplasm

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10
Q

MOA of Aminoglycosides

A

inhibit protein SYnthesis by:
1. prevent the formation of initiation complex
2. Polyribosomes are broken down to non-functional monosomes
3. mRNA is incorrectly read and incorrect AAs are joined to form non-functional or toxic proteins

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11
Q

MOA of Streptomycin

A

changes the shape of the 30S r-RNA and causes mRNA to be read incorrectly

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12
Q

Resistance mechanisms against Aminoglycosides

A
  1. mutation of 30S ribosomal unit binding site: against Streptomycin ONLY
  2. Inhibition of its transport into cell: change in porins
  3. Inactivation by enzymes (Acetyl transferases, Adenyl transferases and Nucleotidyl transferases)
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13
Q

Admin of Aminoglycosides

A

IM admin: once daily dose is preferable for incr. efficacy and decr. toxicity
NO GIVEN ORALLY

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14
Q

Absorption of Aminoglycosides

A

rapidly and completely absorbes–> distributed in ECF and tissues
Penetration into CSF is weak

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15
Q

Excretion of Aminoglycosides

A

mainly unaltered (70-90%) within 24 hrs in urine

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16
Q

Bactericidal effect of Aminoglycosides depend on

A

its concentration
–> greater the conc., the higher the rate of killing

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17
Q

Effect of Aminoglycosides

A

exert a prolong post-antibiotic effect

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18
Q

Toxcity of Aminoglycosides depen on

A

critical plasma levels and time of exposure

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19
Q

Exceptions in Aminoglycosides use

A

when used for synergy againt Endocarditis

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20
Q

SEs of Aminoglycosides

A

Narrow TI toxicity
Nephrotoxic and ototoxic: therapy of >5 days, incr. doses, in elderly and renal insufficiency
Neuromuscular blockage
Electrolyte disturbance
Liver damage
Headache
Skin rash
Fever

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21
Q

Aminoglycosides Narrow TI toxicity depends on

A

Plasma conc.
Duration of exposure
Dosages are in accordance with age, body weight and renal function

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22
Q

How do Aminoglycosides cause Nephrotoxicity

A

they move into the proximal tubule cells vua an uptake system for Oligopeptides
*tubular cells are very sensitive and can be easily damaged

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23
Q

Is the Nephrotoxicity caused by Aminoglycosides reversible

A

yep, generally

24
Q

Which are the most Nephrotoxic Aminoglycosides

A

Neomycin
Gentamycin
Tobramycin

25
Q

What is Ototoxicty

A

damage to the inner ear sensory cells of Vestibular apparatus and Organ of Corti

26
Q

Is Ototoxicty caused by Aminoglycosides reversible

A

only partly

27
Q

Vestibular damage AEs due to Aminoglycosides

A

vertigo
Ataxia
loss of balance

28
Q

Which are the most Vestibulotoxic Aminoglycosides

A

Gentamycin
Streptomycin

29
Q

Cochlear damage AEs due to Aminoglycosides

A

deafness

30
Q

Which are the most Ototoxic Aminoglycosides

A

Amikacin
Neomycin
Kanamycin

31
Q

Effect of Streptomycin taken during Pregnancy

A

causes deafness in child

32
Q

How do the Aminoglycosides cause Neuromuscular Blockage

A

by decr. prejunctional ACh release and decr. post synaptic sensitivity
SEs: drooping of eyelid)

33
Q

DIs with Aminoglycosides

A

General Anaesthetics: incr. neuromuscular blocking effect–> respiratory distress
Neuromuscular blocking agents:
Oto/Nephrotoxic agents: vancomycin, Amphotericin B
Loop diuretics: incr. nehprotoxicty

34
Q

Cautions and CIs in Aminoglycosides

A

Elderly
Renal insufficency
Neonates
Strong Caution-CI: Pregnancy(Streptomycin)
CIs: Myasthenia gravis

35
Q

Effect of Macrolides at different dosages

A

Low: Bacteriostatic
High: Bactericidal

36
Q

Name a Protoype Macrolide

A

Erythromycin

37
Q

Which are the newer Macrolides

A

Azithromycin
Clarithromycin
Roxithromycin

38
Q

PK of Newer Macrolides

A

longer elimination T1/2=less dosing
lower GIT SEs

39
Q

Spectrum/Uses of Macrolides

A

Alternative drug for those allergic to Penicillin
Respiratory infections
Neonatal infections
Ocular infections
Genital Chlamydial infections
Treatment of Community-acquired pneumonia (shows incr. resistance)

40
Q

Macrolides are 2nd line agents in

A

Endocarditis

41
Q

Uses of Newer Macrolides

A

Eradication of H.Pylori in PUD in penicillin allergy patients:
C/A+ metronidazole+ Omeprazole
2nd line agents in Rickettsial infections

42
Q

Spectrum/Uses of Erythromycin

A

Corynebacterium Diphtheriae infections
2nd line agent in acne

43
Q

Which Macrolides are CI in Pregnant women

A

Erythromycin/Azithromycin
*CI in syphilis for pregnant women allergic to Pencillins

44
Q

MOA of Macrolides

A

Attach reversibly to bacterial 50S subunit–> bind to it close to the sites for Chloramphenicol and Clindamycin–> competitively inhibit binding when given together
–> inhibit translocation

45
Q

MOA of Erythromycin

A

binds to 50S and prevents movement along mRNA

46
Q

Resistance mechanisms against Macrolides

A
  1. Reduced cell membrane permeability or active efflux–> reduced entry+efflux
  2. Production of Esterases that hydrlise macrolides
  3. Modification of ribosomal binding site
47
Q

What affects Erythromycin absorption

A

formulation uses
Gastric acidity
Food

48
Q

Admin of Macrolides

A

Orally as Stearate salt or Esterified form(estolate: shows nest absorption not affected by gastric activity)

49
Q

Admin of Erythromycin

A

Base and stearate: food decr. its absorption

50
Q

T1/2 of Macrolides

A

E: 1.5-2 hrs
C: 3-4 hrs
A: 11-14 hrs

51
Q

Metabolism and Excretion of Macrolides

A

M: liver, high protein binding
E: bile, small unchanged amount in urine

52
Q

SEs of Macrolides

A

GIT intolerance: abd pain, cramping, NV, diarrhea
Allergic rxns: rare
Hepatotoxicty: estolate admin >10 day
Inhibit liver enzymes: only 2

53
Q

Which Macrolides inhibit the CYP450 enzymes

A

Erythromycin
Clarithromycin

54
Q

How do Macrolides cause Hepatotoxicty

A

-Estolate taken >10 days cuases IRREVERSIBLE Cholestatic Jandice
-Benign serum elevations of Serum Transaminase

55
Q

DIs with Macrolides

A
  1. Serum conc. of different drugs incr. (theophylline and warfarin
  2. Reduced efficacy of COC
56
Q

Caution/CIs with Macrolides

A

Liver disease
Impaired biliary function
CIs: porphyria (erythromycin)
Heart disease (clarithromycin & Azithromycin): prolonges QT interval=arrythmias may occur

Pharmacology (50 decks)

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