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Chloramphenicol
ID Week 2
9
Pharmacology
Graduate
04/15/2010

Additional Pharmacology Flashcards

 


 

Cards

Term
How does chloramphenicol work?
Definition

Binds to 50S ribosomal subunit, inhibiting protein synthesis.

Note: Binds to similar site on 50S ribosome as macrolides.

Term
Which antibiotics work by binding to the 50S ribosomal subunit?
Definition

Macrolides

Chloramphenicol

Linezolid

Lincosamides (clindamycin)

Term
Which antibiotics work by binding to the 30S ribosomal subunit?
Definition

Tetracyclines and tigecyline

Aminogylcosides

Term
What are targets of chloramphenicol?
Definition

Gram+, Gram-, aerobic and anaerobic

Mycoplasma, Chlamydia, Rickettsia

Term
Is chloramphenicol bacteriostatic or bactericidal?
Definition

Bacteriostatic.

Term
Why is chloramphenicol rarely used?
Definition

Serious adverse effects (bone marrow toxicity)

Term
What are adverse effects of chloramphenicol?
Definition

Serious side effects limit use.

 

Bone Marrow Toxicity:

-- Bone marrow suppression (reversible): due to inhibition of mitochondrial protein synthesis

-- Aplastic anemia (rare, but fatal): onset weeks to months after drug is stopped

-- Higher risk of developing leukemia later in life


Gray Baby Syndrome in newborns (40% fatal)

-- Only with chloramphenicol; due to mitochondrial protein synthesis inhibition (according to Shewach) 

Note: Textbooks says it's due to lack of liver enzymes that metabolize drug, leading to toxic buildup

-- Severe GI and respiratory disturbances

Term
How is chloramphenicol eliminated?
Definition

Glucouronidation in liver to inactivate, then excreted renally.

Note: Neonates lack UDP-glucuronyl transferase and can't eliminate chloramphenicol and its toxic metabolites. This leads to Gray Baby Syndrome (Shewach says Gray Baby Syndrome is due to mitochondrial protein synthesis inhibition).

Term
What are clinical uses of chloramphenicol?
Definition

Almost never used due to risk of serious adverse effects (aplastic anemia).


Used for staphylococcal and unknown mixed brain abscesses (great CSF penetration). Alternative treatment for meningitis caused by N. meningitidis, S. pneumoniae, H. influenzae if patient is allergic to penicillins/cephalosporins (activity is somehow cidal against these organisms).

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