Protein Synthesis Inhibitors

Question 1

Macrolides MOA

Answer 1

Inhibition of protein synthesis, binds 50S ribosomal subunit, selective toxicity - no binding to mamillian ribosome. Bacteriostatic

Question 2

Macrolide Examples

Answer 2

Erythromycin
Clarithromycin
Azithromycin

Question 3

Macrolide distribution

Answer 3

Wide, except for CNS. Crosses placenta

Question 4

Erythromycin Metabolism/excretion

Answer 4

Liver, excreted in bile. Avoid in liver disease.

Excreted in breast milk - check infants for thrush

Question 5

Clarithromycin metabolism/excretion

Answer 5

Renally eliminated, may require adjustment

Excreted in breast milk - check infants for thrush

Question 6

Macrolide uses, gram + cocci

Answer 6

alternative in penicillin allergic patients

Streptococci (phayngitis), pneumococci (pneumonia)

Question 7

Macrolide uses, gram - cocci

Answer 7

Moraxella catarrhalis (otitis media, community acquired pneumonia)

Question 8

Macrolide uses, gram - bacilli

Answer 8

H. influenzae –> upper respiratory infections, bronchitis

Azithromycin and Clarithromycin are the best

Question 9

Macrolide uses, atypicals

Answer 9

Chlmydia (trachoma, community acquired pneumonia, urethritis) -- Azithromycin 
Mycoplasma pneumoniae (community-acquired pneumonia)

Question 10

Azythromycin Metabolism

Answer 10

NOT metabolized, high tissue penetration

Excreted in breast milk, check infant for thrush

Question 11

Macrolide drug interactions

Answer 11

Erythromycin and clarithromycin are inhibitors of cytochrome p450

Question 12

Macrolide heart ADR

Answer 12

prolongs the QT interval – caution with other QT-prolonging drugs

Question 13

Tetracycline MOA

Answer 13

Inhibition of bacterial protein synthesis, binds 30S ribosome, selective toxicity due to human cell ability to efflux the drug. Bacteriostatic

Question 14

Tetracycline Examples

Answer 14

Doxycycline

Minocycline

Question 15

Tetracycline Absorption

Answer 15

Give on an empty stomach, impaired by milk products

Question 16

Tetracycline distribution

Answer 16

Tissue and fluid penetration is excellent - including placental and fetal circulation

Question 17

Tetracycline Metabolism/excretion

Answer 17

Concentrates in liver, use with caution in liver impairement.
Doxycycline is choice for those with renal disease

Question 18

Doxycycline use, gram + cocci

Answer 18

Methicillin resistant staphylococcus aureus (skin infection, pneumonia)
Most organisms are resistant

Question 19

Doxycycline use, gram - cocci

Answer 19

Moraxella catarrhalis (otitis media, CAP)
Most organisms are resistant

Question 20

Doxycycline uses, gram - baccili

Answer 20

Heamophilis Influenzae (otitis media, CAP)
Helicobacter pylori (peptic ulcer disease)

Question 21

Doxycycline use, atypicals

Answer 21

Chlamydia (trachoma, urethritis, CAP)
Mycoplasma pneumoniae (CAP)

Question 22

Tetracycline ADR

Answer 22

Teeth and bones! Avoid in later half of pregnancy and in children under 8 years old.
Photosensitivity
Yeast overgrowth

Question 23

Tetracycline DDI

Answer 23

Antacids or iron supplements - decreases bioavailability by forming insoluble salts in the stomach

Question 24

Clindamycin MOA

Answer 24

Inhibition of protein synthesis by binding to 50S ribosome

Bacteriostatic

Question 25

Clindamycin Distribution

Answer 25

Penetrates most tissues well, ESPECIALLY BONE | NOT into CSF,

Question 26

Clindamycin metabolism

Answer 26

Hepatic. | Excreted in breast milk

Question 27

Clindamycin use, gram + cocci

Answer 27

Streptococci ( pneumonia, pharyngitis) MSSA MRSA

Question 28

Clindamycin use, anaerobes

Answer 28

Bacteroides fragilis (abcesses)

Question 29

Clindamycin ADR

Answer 29

Pseudomembranous colitis - allows Clostridium difficile to become overgrown

Question 30

Aminoglycoside MOA

Answer 30

Inhibits protein synthesis initiation, is transported into bacteria, requiring O2 so NOT effective against anaerobes Bactericidal, concentration dependent.

Question 31

Aminoglycoside Examples

Answer 31

Tobramycin | Gentamycin

Question 32

Aminoglycoside Absorption

Answer 32

Not absorbed orally, too polar. | IM or IV

Question 33

Aminoglycoside distribution

Answer 33

Limited to ECF, excluded from the CNS and eye but inflammation increases its penetration Accumulates in renal cortex and inner ear

Question 34

Aminoglycoside metabolism/ecretion

Answer 34

Not metabolized, purely excreted by kidneys - renal dosing necessary

Question 35

Aminoglycoside uses, gram negative

Answer 35

Pseudomonas aeruginosa | E. coli (UTI*)

Question 36

Aminoglycoside ADR

Answer 36

Ototoxic | Renal toxic