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2.1 Antimicrobial Pharm > Protein Synthesis Inhibitors > Flashcards

Protein Synthesis Inhibitors Flashcards

1
Q

What are the 8 basic categories of Protein Synthesis Inhibitors?

A
  • Initiation (Aminoglycosides, Linezolid)
  • Elongation 1 (Tetracyclines, Streptogramins)
  • Elongation 2 (Chloramphenicol)
  • Elongation 3 (Macrolides/Ketolides, Clindamycin)
  • Gylcylcyclines
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2
Q

What class of drug binds to the 30S subunit and prevents INITIATION of the whole peptide?

A
  • Aminoglycosides

- A ‘intitiates’ alphabet and the protein inhibitors

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3
Q

Aminoglycosides prevent ______-tRNA from binding to the ________ site on the 30S subunit.

A
  • Methionine-tRNA (start codon=AUG)

- P SITE is the site of initiation (contrast with ‘A site’ where incoming Aminoacyl-tRNAs arrive)

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4
Q

What drug binds the 50S subunit towards the 30S face and prevents the two from hooking up (thus prevents intiation)?

A

Linezolid

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5
Q

The two classes of drug that screw with INITIATION of bacterial protein synthesis are?

A

-Aminoglycosides and Linezolid

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6
Q

What class of drug binds at the 30S subunit and prevents the FIRST STEP IN ELONGATION of the bacterial peptide?

A

-Tetracyclines

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7
Q

Tetracyclines prevent ___________ from binding to the __________ site on the 30S subunit.

A
  • incoming Aminoacyl-tRNAs

- A SITE

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8
Q

What drugs bind to the 50S subunit and prevent the enzyme Peptidyl Transferase?

A

-Chloramphenicol

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9
Q

_________ prevents the enzyme that adds a single new amino acid to the growing peptide chain.

A

-Chloramphenicol

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10
Q

What drugs bind the 50S subunit and prevent the last step in peptide elongation (translocation)?

A

-Macrolides and Clindamycin

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11
Q

Macrolides+Clindamycin prevent the process of ____________, which involves the ribosome advancing 3 base pairs towards the 3’ end of the bacterial mRNA.

A

-translocation

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12
Q

What is the only protein synthesis inhibitor that is bacteriostatic PLUS bacteriocidal?

A
  • Aminoglycosides

- they can cause misreading of mRNA (frameshift-like effect)

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13
Q

Aminoglycosides are to Linezolid as Tetracyclines are to _______________?

A

Dalfopristin/Quinupristin (streptogramins)

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14
Q

What subunit is a common site of binding of drugs to combat VRSA and VRE?

A
  • 50S subunit

- seen in Linezolid and Dalfopristin/Quinupristin

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15
Q

How are aminoglycosides taken up into the bacteria, and what implications does this have on spectrum of action?

A
  • REQUIRES O2 dependent uptake

- therefore, NOT effective vs ANEROBES

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16
Q

What 3 aminoglycosides are used often in combo with other drugs?

A

-TAG (Tobramycin, Amikacin, Gentamicin)

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17
Q

What aminoglycoside is topical, therefore is often used in bowel sx?

A

-Neomycin

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18
Q

What aminoglycoside is used often in TB, and is DOC for bubonic plague and Tularemia?

A

-Streptomycin

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19
Q

Describe the 4 big time toxicities associated with Aminoglycosides.

A
  • Nephrotoxicity (ATN of the PCT)
  • Ototoxicity
  • Teratogenic
  • Neuromuscular blockade (decr Ach, like botox!)
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20
Q

What component of a triple antibiotic ointment (Neosporin) will most likely cause contact dermatitis?

A
  • Neomycin

- (polymyxin and bacitraicin do not)

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21
Q

The primary mechanism of resistance to Aminoglycosides is?

A

-production of conjugating enzymes (aka transferase enzymes) that chemically modify the drug

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22
Q

Tetracylines are broad spectrum drugs, but what specific infections should we remember for Doxycycline in particular?

A
  • DOC for Rickettsia infections (RMSF)
  • DOC for Spirochetes (Lyme)
  • Mycoplasma, Chlamydia
  • big in Brucella, Treponema, and Vibrio too
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23
Q

Demeclocycline is a tetracycline that should only be thought about for?

A
  • SIADH treatment!

- blocks V2R on the collecting duct

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24
Q

What are some common causes of SIADH?

A
  • lesion to posterior pituitary

- small cell CA of lung (paraneoplastic)

25
Q

What psych drug has a similar action to Demeclocycline?

A

-Lithium

26
Q

Tetracyclines block what specific step of protein synthesis by binding to 30S?

A

-block first step of ELONGATION

27
Q

Tetracyclines complex with ___________ in the gut which __________ the drug’s absorption.

A
  • divalent Cations (Mg, Ca, etc.)

- decrease

28
Q

Give somes sources of divalent cations.

A
  • antacids
  • milk
  • Fe containing supplements
29
Q

What are the big 3 side effects for Tetracyclines?

A
  • discolored teeth (Ca chelation)
  • Photosensitivity
  • GI distress
30
Q

What is the only type of infection that warrants Doxycycline to children?

A

-Rocky mountain spotted fever (Rickettsia rickettsii)

31
Q

What are 3 classes of drugs that cause photosensitivity?

A
  • Quinolones
  • Tetracyclines
  • Sulfonamides
32
Q

What is the main mechanism for bacterial resistance to tetracyclines?

A

-efflux pumps (ex: P glycoprotein)

33
Q

What is the name and function of the enzyme blocked by Chloramphenicol?

A
  • Peptidyl Transferase

- adds another amino acid to the peptide chain

34
Q

What are 2 key uses for Chloramphenicol?

A
  • meningitis (H. flu, N. men, Strep pneumo)

- sepsis

35
Q

Describe the use of Chloramphenicol.

A
  • not used much in US due to side effects

- used more in poor countries since its cheap

36
Q

What clue in Chloramphenicol’s name tells us its highly lipid soluble, thus good for CNS?

A

-all drugs with ‘phen’ in the name have a ring, thus are highly lipid soluble

37
Q

Describe the metabolism of Chloramphenicol.

A

-Conjugated in the liver by UDP-glucuronyl transferase

38
Q

What type of patients lack the key enzyme in metabolism of Chloramphenicol, and how does this manifest?

A
  • Neonates have reduced UDP-glucuronyl transferase

- Grey baby syndrome +kernicterus (bilirubin dep. in brain)

39
Q

What else is UDP-glucuronyl transferase important in, and what diseases are involved?

A
  • conjugation of bilirubin in liver
  • Gilbert’s syndrome: mild decrease in UGT
  • Crigler Najjar 1: absent UGT
40
Q

What 2 side effects must we know for Chloramphenicol?

A
  • Grey baby syndrome

- Anemia/Bone marrow suppression

41
Q

Macrolides are a class of drug that inhibit the _________ step of peptide elongation, known as _________

A
  • last

- translocation

42
Q

Macrolides are extremely wide spectrum, so what are some key infections to know?

A

-G+ cocci, ATYPICALS, LEGIONELLA, MAC, H. pylori, etc

43
Q

Macrolides all end in __________

A

thromycin

44
Q

Macrolides all inhibit P450 in the liver EXCEPT

A

Azithromycin (more water soluble)

45
Q

GI distress is the primary SE of Macrolides. Why is it more substantial here than other antibiotics?

A
  • stimulates MOTILIN receptors in the gut

- along with possible disruption of normal flora

46
Q

What are some side effects to know for Macrolides?

A
  • GI distress
  • Reversible deafness @ hi dose (Ex: MAC)
  • prolonged QT interval
  • cyp450 inducer (know Digoxin especially!)
  • eosinophilia, skin rash
47
Q

What is the one Ketolide to know?

A

Telithromycin

48
Q

Describe when+why Telithromycin is used in place of macrolides.

A
  • when bug in Macrolide resistant!
  • macrolides use domain V of 23S area of 50S subunit (is site of resistance)

-ketolides use DOMAIN II of 23S area of 50S subunit

49
Q

What is the big gene in resistance to Macrolides, how does it help the bug out, and who uses it?

A
  • erm gene (erythromycin ribosome methylase)
  • methylates an Adenine @ domain V
  • G+ can exhibit this (STREP PNEUMO!!)
50
Q

Clindamycin has the same MOA as ___________

A

Macrolides

51
Q

In contrast to macrolides, Clindamycin has a _____________ spectrum

A

narrow

52
Q

What 2 infectious groups should be immediately thought of with Clindamycin?

A
  • Anaerobic infections above the diaphragm

- osteomyelitis (Staph aureus)

53
Q

Pt presents with osteomyelitis, with hx of Sickle cell anemia. Do we use Clindamycin?

A
  • NO! the bug is Salmonella

- use Quinolones

54
Q

Pt presents with osteomyelitis, with hx of IVDU/diabetes. Do we use Clindamycin?

A
  • NO! the bug is Pseudomonas

- use Quinolones

55
Q

What is the primary side efffect of Clindamycin?

A

Pseudomembranous colitis (due to C. diff overgrowth)

56
Q

How would you treat the primary side effect of Clindamycin?

A
  • Metronidazole

- Vancomycin as alternate

57
Q

What is the big side effect to know with Linezolid?

A

-bone marrow suppression/thrombocytopenia

58
Q

Streptogramins are only used when the bug is resistant to _________

A

vancomycin (VRSA, VRE)

2.1 Antimicrobial Pharm (9 decks)

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