Antibacterials: Tetracyclines

Question 1

Oxytetracycline

Answer 1

• family: tetracycline
• mechanism: Binds reversibly to the 30S subunit, blocking the binding of aminoacyl-tRNA to the acceptor site on the mRNA-ribosome complex
• kinetics: Short-acting
• clinical: chlamydia, mycoplasma, acne, rickettsia
• toxicity/interactions: Phototoxicity, Bone/teeth deposition, GI distress, Hepatotoxicity,
• misc: CI in children + pregnant women

Question 2

Chlortetracycline

Answer 2

• family: tetracycline
• mechanism: Binds reversibly to the 30S subunit, blocking the binding of aminoacyl-tRNA to the acceptor site on the mRNA-ribosome complex
• kinetics: Short-acting, not as stable in acid solution as others
• toxicity/interactions: Phototoxicity, Bone/teeth deposition, GI distress, Hepatotoxicity,
• misc: CI in children + pregnant women

Question 3

Doxycycline

Answer 3

• family: tetracycline
• mechanism: Binds reversibly to the 30S subunit, blocking the binding of aminoacyl-tRNA to the acceptor site on the mRNA-ribosome complex
• kinetics: Longer-acting, excreted in feces
• clinical: amebiasis, malaria prevention, Lyme disease
• toxicity/interactions: Phototoxicity, Bone/teeth deposition, GI distress, Hepatotoxicity, Vestibular Toxicity
• misc: CI in children + pregnant women

Question 4

Methacyclin

Answer 4

• family: tetracycline
• mechanism: Binds reversibly to the 30S subunit, blocking the binding of aminoacyl-tRNA to the acceptor site on the mRNA-ribosome complex
• kinetics: Intermediate-acting
• clinical: gonorrhea
• toxicity/interactions: Phototoxicity, Bone/teeth deposition, GI distress, Hepatotoxicity,
• misc: CI in children + pregnant women

Question 5

Minocyclin

Answer 5

• family: tetracycline
• mechanism: Binds reversibly to the 30S subunit, blocking the binding of aminoacyl-tRNA to the acceptor site on the mRNA-ribosome complex
• kinetics: Longer-acting, reaches very high concentrations in tears/saliva
• clinical: eliminates meningococcal carrier state
• toxicity/interactions: Phototoxicity, Bone/teeth deposition, GI distress, Hepatotoxicity, Vestibular Toxicity,
• misc: CI in children + pregnant women