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Flashcards in 8.4 Deck (14):
1

Which drugs are in the category Macrolides? (4)

1) Erythromycin
2) Clarithromycin
3) Azithromycin
4) Telithromycin

2

What is the MOA of Macrolides?

Reversibly bind to the 50S subunit inhibiting translocation.

3

How do Macrolides gain resistance? (3)

3 main mechanisms (usually plasmid encoded):
• Reduced membrane permeability or active efflux
• Production of esterase that hydrolyze drugs (by
enterobacteriaceae)
• Modification of ribosomal binding site (by chromosomal mutation or by a methylase)

4

Macrolides are effective against which bacteria?

Most active against Gram-positive bacteria (some activity against Gram-negatives)

5

What is the DOC for Mycoplasma Pneumoniae?

Macrolides (along with tetracyclines)

Macrolides more safe in pregnancy.

6

What is the DOC for whooping cough?

Erythromycin

7

What is the clinical applications for macrolides?

- Used in empiric therapy of community-acquired
pneumonia (outpatient & in combination with B-lactam for inpatients)

- Treatment of upper respiratory tract & soft-tissue infections (eg, Staph, H.influenzae, S.pneumoniae,
enterococci)

8

What is important to know about the PK of Erythromycin, clarithromycin & telithromycin?

CYP P450 inhibition (NOT azithromycin)

9

What are the adverse effects of Macrolides?

• GI irritation
• Hepatic abnormalities (erythromycin & azithromycin)
• QT prolongation
• Severe reactions are rare (anaphylaxis, colitis)

10

What are the contraindications for Macrolides?

• Statins (due to macrolides inhibiting CYP P450)
• Telithromycin – fatal hepatotoxicity, exacerbations of
myasthenia gravis, & visual disturbances  don’t use for
minor illnesses

11

What is the MOA of Chloramphenicol?

• Enters cells via active transport process
• Binds reversibly to 50S ribosomal subunit (site adjacent to site of action of macrolides & clindamycin)

12

How does Chloramphenicol cause bone marrow toxicity?

Can inhibit protein synthesis in mitochondrial ribosomes

13

Chloramphenicol inhibits which cytochrome enzymes?

1) 3A4
2) 2C9

14

What are the adverse effects of Chloramphenicol?

• GI distress

• Bone marrow depression
• dose-related reversible depression
• severe irreversible aplastic anemia

• Gray baby syndrome (cyanosis), due to drug
accumulation