Tetracyclines Flashcards
What are the main targets of tetracyclines?
Broad Spectrum: G+/G-, some intracellular
How are tetracyclines excreted?
Undergo enterohepatic recycling - levels persist
What is the main mechanism of tetracyclines?
Inhibit binding or aminoacyl tRNA to acceptor site
What are the short acting (T1/2 ~ 6-8 hrs) tetracyclines?
Tetracycline - alternate oral or topical for acne
Oxytetracycline - ophthalmic w/ polymyxin B
What is the intermediate acting (T1/2 ~ 12 hrs) tetracycline?
Demeclocycline - for dilutional hyponatremia w/ SIADH
What is demeclocyclines mechanism in SIADH?
Inhibits a protein kinase in ducts on which ADH depends
What are the long acting (T1/2 ~ 16-18 hrs) tetracyclines?
Doxycycline - oral and IV
Minocyclin - acne et al.
Describe doxycycline.
highly lipophilic, 95% absorbed
Significant excretion in feces - inactive
What is minocycline associated with?
Pulmonary lupus, hypersensitivity pneumonitis, pleural effusions
How does minocycline demonstrate immunomodulatory and antiinflammatory activity?
Blocks synthesis of nitric oxide and activation of microglia > neuronal damage but improves stroke outcome
In what cases is minocycline neuroprotective?
Neurodegenerative disease
Rheumatoid arthritis
What are other side effects of Minocycline?
SLE like syndrome w/ + ANA
In chronic use > nail, skin, sclera pigmentation (reversible), black pigmentation of thyroid, blue-black gums (permanent)
What are some general side effects of tetracyclines?
GI Upset
Photosensitivity
Brown discoloration of teeth (cross placenta)
Slowed growth
What happens if an expired tetracycline is prescribed?
Fanconi-like syndrome from nephrotoxic epianhydrotetracycline
What are the symptoms of fanconi-like syndrome?
N & V, polyuria, glucosuria, acidosis, et al.
