Tetracyclines

Question 1

MOA

Answer 1

Inhibits protein synthesis by binding to the 30S subunit

Bacteriostatic–>Time-dependent

Question 2

MOR

Answer 2

Tetracycline-specific efflux pumps

Ribosomal protection proteins

Enzymatic inactivation

Question 3

Spectrum of activity (Tetracyclines)

Answer 3

Gram (+) aerobes–>monocycline and doxycycline are most active
- MSSA

Gram (-) aerobes
- H. influenza

Anaerobes

Atypical bacteria
- Legionella pneumonphila, chlamoydophila, pneumoniae, and psittaci

Question 4

Spectrum of activity (Tetracycline analogs)

Answer 4

Gram (+) aerobes
- MSSA, MRSA

Gram (-) aerobes
- EEACKSS
- Tetracycline analogs are NOT active against Proteus or Pseudomonas aeruginosa

Anaerobes:
- ADA
- BDA

Atypical bacteria

Question 5

Absorption

Answer 5

Tigecycline and eravacycline are only available IV; doxycycline and minocycline are available IV and PO. tetracycline is only available PO

Absorption of the oral tetracyclines and omadacycline is impaired by concurrent ingestion of ZICAM + bismuth

Question 6

Distribution

Answer 6

Widely distributed into tissues and fluids–> prostatic and seminal fluids

Only small amounts of tetracyclines and tetracycline analogs diffuse into the CSF

Question 7

Elimination

Answer 7

Tetracyclines are excreted mainly by non-renal routes, and do not require dose adjustments in renal insufficiency

Tetracycline analogs are mainly eliminated by biliary/fecal excretion
- No renal dose adjustments but dose adjustments of tigecycline and eravacycline are required in severe hepatic impairment

Question 8

Clinical uses (Tetracyclines)

Answer 8

Mild to moderate outpatient community-acquired pneumonia (doxycycline)

Chlamydial infections including nongonococcal urethritis

Question 9

Clinical uses (Tetracycline analogs)

Answer 9

NOT proteus spp. or Pseudomonas spp.

Question 10

Adverse effects

Answer 10

GI–>N/V/D

Photosensitivity

Pregnancy Category D–> permanent discoloration teeth (black/gray)