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Pharm Exam 5 > Protein Synthesis Inhibitors I > Flashcards

Protein Synthesis Inhibitors I Flashcards

1
Q

The bacterial ribosome is ___S.

A

70

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2
Q

Bacterial ribosome subunits.

A

50 and 30s

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3
Q

Drugs that are inhibitors of protein synthesis.

A

Tetracyclines
Chloramphenicol
Macrolides

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4
Q

These protein synthesis inhibitors inhibit the 30s subunit of the bacterial ribosome.

A

Tetracyclines

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5
Q

These protein synthesis inhibitors inhibit the 50s bacterial ribosomal subunit.

A

Chloramphenicol

Macrolides

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6
Q

These protein synthesis inhibitors prevent aminoacyl tRNA from bringing over an amino acid.

A

Tetracyclines

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7
Q

Tetracyclines bacteriocidal or static?

A

Static

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8
Q

Tetracycline MOA

A

Prevents aminoacyl-tRNA from binding to its acceptor site on the ribosome.

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9
Q

How do tetracyclines penetrate the microorganism?

A

Active and Passive diffusion

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10
Q

Mechanism of resistance for tetracycline.

A

1) Decreased drug penetration into the microorganism.
2) Increased drug efflux from the microorganism.
3) Decreased affinity for the 30s ribosome.
4) Cross-resistance among all Tetracyclines.

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11
Q

Cross-resistance

A

Resistance to a substance bc of exposure to a similarly-acting substance.

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12
Q

T/F: if patient is resistant to one tetracycline, they may not be resistant to all the tetracyclines.

A

False.

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13
Q

Which organ eliminates most Tetracyclines from the body?

A

Kidney

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14
Q

Which organ eliminates tetracyclines with a low renal clearance?

A

Gall bladder

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15
Q

These tetracyclines are eliminated through the gall bladder.

A

Doxy and Minocycline

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16
Q

What is Arestin AKA?

A

Minocycline

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17
Q

Clinical uses of Tetracyclines

A

1) GI and GU infections (but most bacteria causing these infections are resistant, so we try to use different drugs).
2) Local administration in periodontitis (Minocycline/Arrestin).

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18
Q

Adverse effects of Tetracycline use.

A

1) Tooth discoloration
2) Headaches and nausea
3) Photosensitivity
4) Liver damage
5) Superinfection

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19
Q

What is superinfection?

A

When you get another infection while treating an infection you currently have.

The new organism will be resistant to the antibiotic you used to treat the primary infection.

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20
Q

Organisms that cause superinfections.

A

1) Staph aureus
2) Candida albicans
3) C. difficile

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21
Q

Risk factors for superinfections.

A

1) In-hospital stays for more than 6 days.

2) Use of a broad spectrum antibiotic.

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22
Q

These tetracyclines do NOT accumulate in the body with kidney dysfunction bc they’re eliminated by the liver.

A

Doxy and Minocycline

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23
Q

Tetracycline drug interactions:

A

1) Bony structures and teeth.

2) Can cause Nitrogen retention when used with diuretics.

24
Q

This protein synthesis inhibitor does NOT bind to mammalian ribosomes.

A

Chloramphenicol

25
Q

This protein synthesis inhibitor is:

Broad-spectrum
Inexpensive
Orally administered

A

Chloramphenicol

26
Q

Reversibly binds to the 50s subunit of bacteria to inhibit protein synthesis, and does not affect mammalian ribosomes.

A

Chloramphenicol

27
Q

Chloramphenicol specificity

A

More specific at inhibiting gram-negative organisms.

28
Q

Microbes inhibited by Chloramphenicol

A

H. influenzae

Neisseria meningitidis

29
Q

This is made by plasmids to inactivate chloramphenicol .

A

Chloramphenicol acetyltranferase

30
Q

Chloramphenicol resistance

A

1) Presence of mutants that are less permeable to chloramphenicol.
2) Plasmids make Chloramphenicol acetyltransferase to acetylate chloramphenicol, this inactivating it.

31
Q

How is chloramphenicol inactivated?

A

Acetylation and by conjugation with glucuronic acid (glucuronidation).

32
Q

Very important adverse effect of Chloramphenicol.

A

Inhibits CYP450, so Warfarin and Phenytoin levels increase in the body.

33
Q

These drugs cause Chloramphenicol metabolism.

So more chloramphenicol is needed to have a therapeutic effect when the person is taking these drugs.

A

Rifampin and Phenobarbital

34
Q

Chloramphenicol distribution in the body.

A

Concentration in CNS = that in serum

35
Q

How is Chloramphenicol inactivated?

A

Glucuronidation and acetylation.

36
Q

How does the dose affect Chloramphenicol in cases of renal insufficiency?

A

It doesn’t!

Because the liver breaks down Chloramphenicol.

37
Q

This organ breaks down Chloramphenicol.

A

Liver

38
Q

How is the dose of Chloramphenicol affected in cases of hepatic failure?

A

Need to lower the dose bc the liver can’t properly break it down.

39
Q

How is dose of Chloramphenicol affected by newborns?

A

Has to be reduced bc babies don’t have the means to glucuronidate, and thus, breakdown Chloramphenicol.

40
Q

Too high a dose of Chloramphenicol in babies causes this.

A

Gray Baby Syndrome:

Vomiting, flaccidity
Hypothermia
Gray color
Shock
Vascular collapse
41
Q

Large protein synthesis inhibitors derived from Streptomyces.

A

Macrolides

42
Q

Prototype for the macrolides.

A

Erythromycin

43
Q

Clinical use of Erythromycin Macrolide

A

1) Penicillin substitute for those allergic to Penicillin with strep or pneumococci infections.
2) Starred: As prophy against bacterial endocarditis during dental procedures in people with valvular heart disease.

44
Q

This antibiotic is beginning to replace Erythromycin.

A

Clindamycin

45
Q

Macrolides MOA

A

Inhibit formation of the 50s subunit, and prevent protein elongation in the 50s subunit.

46
Q

Optimal pH for Erythromycin to work.

A

Basic (so it needs a protective coating for when we take it orally and it goes into the acidic stomach).

47
Q

These protein synthesis inhibitors do not affect mammalian ribosomes.

A

Chloramphenicol

Macrolides

48
Q

4 Types of resistance to Erythromycin

A

1) Reduced permeability of the cell membrane (so the antibiotic can’t get into the bacterial cell).
2) Increased efflux out of the cell.
3) Production of esterases that break down macrolides.
4) Methylation of rRNA

49
Q

Cross resistance is seen in which protein synthesis inhibitor antibiotics?

A

Tetracyclines and Macrolides

50
Q

Why do patients with renal failure not need to reduce their dose of Erythromycin?

A

BC it’s excreted in the liver.

51
Q

What does dosing of macrolides depend on?

A

Lipid solubility.

52
Q

Dosing:
Erythromycin
Clarithromycin
Azithromycin

A

Erythromycin 4x/day
Clarithromycin 2x/day
Azithromycin 1x/day

53
Q

Erythromycin adverse reactions.

A

Anorexia, N,V,D

GI intolerance

Erythromycin inhibits CYP 450 (like Chloramphenicol!).

Leads to increased serum concentration of drugs that undergo metabolism thru CYP450 enzymes:
Warfarin
Cyclosporine

Possible QT prolongation

54
Q

This macrolide dosage is 4 times a day, so patient compliance is low.

A

Erythromycin

55
Q

This macrolide has to be taken once a day, so it has high patient compliance.

A

Azithromycin

A = first letter of the alphabet = 1 time a day

56
Q

These protein synthesis inhibitors inhibit CYP450 enzymes, so Warfarin and Phenytoin levels increase.

A

Chloramphenicol and Erythromycin

Pharm Exam 5 (8 decks)

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