Tetracyclines Flashcards
Tetracyclines
Broad spectrum STATIC vs G+, G- and some intracellular organisms
What is the mechanism of Tetracyclines?
Inhibit binding of aminoacyl tRNA to acceptor site of ribosome
Tetracycline
- Short acting Tetracycline
* Used for acne
Minocycline
- Long acting (highly lipophilic) Tetracycline
- Used for acne
- Associated with pulmonary complications
- Appears to be neuroprotective
- Side effects: reversible skin pigmentation and blue-black gum coloration
Demeclocycline
- Intermediate acting Tetracycline
- Used for chronic dilution hyponatremia in Syndrome of Inappropriate ADH (SIADH)
- Photosensitivity common
What is the mechanism of Syndrome of Inappropriate ADH (SIADH)?
Inhibits a protein kinase in the kidney’s collecting ducts on which ADH depends
Doxycycline
- Long acting (highly lipophilic) Tetracycline
* Oral and IV
What are some side effects common to all Tetracyclines?
- GI upset (take w/food!)
- Slowed growth
- Brown discoloration of teeth (permanent)
- Photosensitivity (particularly w/demeclocycline)
What can happen if you take an expired Tetracycline Rx?
Fanconi-like Syndrome
• Nephrotoxic metabolite → nausea, vomiting, polyuria, polydipsia, glucosuria, aminoaciduria, metabolic acidosis
What things lower absorption of all Tetracyclines and how?
Dairy products and antacids through chelation with calcium phosphate
Tigecycline
• Parenteral, long acting Tetracycline
• Derivative of minocycline
• Used for complicated skin, intraabdominal infections and community acquired bacterial pneumonia
- Increased risk of mortality if hospital-acquired pneumonia
What is the mechanism of Tigecycline?
- Same as Tetracyclines but tidal in some species
* Greater activity vs tetracycline-sensitive G+/G- and MRSA from greater steric hindrance
In which patients should the Tigecycline dose be lowered and why?
Pts w/severe hepatic impairment or else clearance will go down → half-life will go up → increased risk of toxicity
