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Pharm Exam 1 > Protein Synthesis Inhibitors > Flashcards

Protein Synthesis Inhibitors Flashcards

1
Q

List the tetracyclines

A

tetracycline, doxycycline, minocycline, tigecycline*

*technically a glycylcyline

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2
Q

List the aminoglycosides

A

streptomycin, gentamycin, neomycin, amikacin

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3
Q

What pregnancy category do the protein synthesis inhibitors belong to?

A

Pregnancy Category D

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4
Q

Describe the mechanism of action of tetracyclines

A

They reversibly bind to the 30S subunit of ribosomes, blocking tRNA from binding at the A site and preventing addition of amino acids. They are bacteriostatic.
**only accumulate in bacteria, not eukaryotes

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5
Q

Adverse effects of tetracyclines

A

Modification of gut flora, superinfection, outdated meds can cause nephrotoxicity
**monocycline can cause vestibular dysfunction from CNS penetration

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6
Q

Indications for tetracyclines

A

Gram+/- bacteria.

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7
Q

ADME of tetracyclines

A

Widely distributed, particularly in bones and teeth. Absorption impaired by food and divalent metals (Mg2+, Fe2+, etc). Oral admin w/ small intestine absorption EXCEPT tigecycline (given IV). Doxy/mino have longer half-lives. Doxy/mino/tige excreted via bile so they’re safer for renal impaired patients.

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8
Q

Mechanisms of resistance in tetracyclines

A

Increased efflux/decreased influx, ribosome protection, inactivation via acetylation

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9
Q

Contraindications for tetracyclines

A

Children under 8, pregnant or breastfeeding women

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10
Q

Describe the mechanism of action of aminoglycosides

A

Bactericidal. Irreversibly binds to 30S subunit, blocking initiation of protein synthesis & elicits termination. Also incorporates incorrect amino acids. Increases permeability & leakage of cell membrane. Concentration-dependent killing.

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11
Q

Indications for aminoglycosides

A

Aerobic G- enteric bacteria

  • *synergistic effect w/ B-lactams for endocarditis
  • *has strong postantibiotic effect (hours) in the absence of detectable drug levels
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12
Q

ADME of aminoglycosides

A

Poorly absorbed orally, so given IV. Requires oxygen to cross cell-membranes, so does not work in anaerobic conditions. Uptake increased by cell wall inhibitors (e.g. B-lactams). Excreted via urine.

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13
Q

Mechanisms of resistance in aminoglycosides

A

*Enzymatic inactivation! Also, impaired uptake (e.g. anaerobic conditions) and mutation of ribosomal protein (usually affects streptomycin)

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14
Q

Adverse effects of aminoglycosides

A

Common. 10-25% ototoxic (can be irreversible, especially amikacin and neomycin) with vestibular and auditory damage. Also 10-25% nephrotoxic.

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15
Q

What drug classes are protein synthesis inhibitors?

A

Tetracyclines, Aminoglycosides, and Chloramphenicol

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16
Q

Describe the mechanism of action of chloramphenicol

A

Bacteriostatic. It binds to the 50S subunit of the ribosome and inhibits peptidyltransferase activity (anticodon can’t move between A and P sites).
**It can interfere with eukaryotic mitochdrial ribosomes causing cell death from inhibition of aerobic metabolism.

17
Q

ADME of chloramphenicol

A

Absorbed rapidly after oral administration. Metabolized in the liver and inhibits some P450 enzymes so be careful. Penetrates CNS, CSF, breast milk, and placenta.

18
Q

Adverse effects of chloramphenicol

A

Bone marrow suppression (reversible), aplastic anemia (irreversible), “Gray Baby” syndrome (infants lack UGT needed to excrete the drug)

19
Q

Name the macrolides

A

Erythromycin, azithromycin, clarithromycin

20
Q

Mechanism of action for erythromycin, azithromycin, clarithromycin, and clindamycin

A

Bind to the 50S ribosomal subunit inhibiting translocation and thus stopping protein synthesis.

21
Q

Erythromycin is effective against

A

Gram + organisms, some Gram -. Good alternate for those w/ hx of penicillin/cephalosporin allergy.

22
Q

Mechanism of resistance of erythromycin

A

Efflux, mutation at the binding site (methylase adds a methyl group to the binding site so drug can’t bind), or inactivation

23
Q

ADME of erythromycin

A

PO or parenteral, but food interferes. Biliary excretion. Reaches fetus but not CNS. P450 inhibitor.

24
Q

Adverse effects of erythromycin

A 
Liver toxicity (acute cholestatic hepatitis), reversible hearing loss, prolonged QT w/ VTACH
GI intolerance (stimulates gut motility)
*sometimes given post-op for this reason
25
Q

ADME of clarithromycin

A

Metabolized by liver, renal excretion.

26
Q

Adverse effects of clarithromycin

A

Reversible hearing loss, Category C, drug-drug interactions (P450 inhibitor)

27
Q

ADME of azithromycin

A

Taken up well by the tissues, which slowly leak drug back into system for long half-life. Doesn’t penetrate CNS.
***NOT a P450 inhibitor like other macrolides.

28
Q

Indications for clindamycin

A

Very much like erythromycin, and is good for MRSA!

*Doesn’t work against Gram - aerobes b/c poor permeability of outer membrane.

29
Q

ADME and adverse effects for clindamycin

A 
Hepatic metabolism (reduce dose if hepatic dz) and urine/bile excretion. 
*Can cause C. diff!
30
Q

Mechanisms of action and resistance of metronidazole

A

Disrupts DNA by forming covalent bonds once activated by nitroreductase. Resistance occurs when nitroreductase levels are reduced.
*Treats C. diff

31
Q

ADME and adverse effects of metronidazole

A

Disulfiram-like rxn when taken w/ alcohol (lots of vomiting). Liver metabolism, P450 inhibitor. Can make urine dark red/brown and tastes metallic.

32
Q

What drugs can be given in the case of vancomycin resistance?

A

Linezolid (protein synthesis inhibitor) and daptomycin (membrane depolarizer)

33
Q

Mechanism of action of linezolid

A

Used for vanc-resistant infections, Gram +. Prevents formation of the initiation complex (binds 23S RNA on 50S and prevents it from attaching to 70S) so bacteria can’t synthesize protein

34
Q

Adverse effects of linezolid

A

Myelosuppression (thrombocytopenia, leukopenia, anemia) and reversible peripheral/optic neuropathy. Mild inhibitor of monoamine oxidase (htn if taken w/ foods rich in tyramine aka “wine and cheese effect”)

35
Q

Mechanism of action of daptomycin

A

Should be reserved for vanc-resistant Gram + infections, specifically S. aureus and VRE. Uses Ca++ to form ion-conducting pore to influx Na+ and efflux K+

36
Q

ADME and adverse effects of daptomycin

A

Excreted via urine (adjusted dose for renal dz patients). Can cause muscle weakness/discomfort, may want to stop statins/other agents associated with rhabdomyolysis.

Pharm Exam 1 (8 decks)

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