Tetracyclines Flashcards
Chlortetracycline + Tetracycline
Bacteriostatic
Inhibits protein synthesis by reversibly binding to 30S ribosomal unit, preventing protein transcription. also believed to alter cytoplasmic membrane permeability; in high doses can inhibit protein synthesis in mammalian cells
Many bacteria are now resistant, but may be useful for mycoplasma, rickettsia, spirochetes, chlamydia
use with caution in liver and renal dysfunction, pregnancy
overuse may result in superinfections
Oxytetracycline, chlortetracycline, and tetracycline share nearly identical spectrums of activity and patterns of cross-resistance, and a tetracycline susceptibility disk is often used for in vitro testing for chlortetracycline susceptibility.
AE: GI distress, staining of developing teeth and bones, photosensitivity, GI
cats do not tolerate oral tetracycline or oxytetracycline very well; long term use may cause urolith formation in dogs
Doxycycline
Bacteriostatic, broad spectrum coverage of gram positive, gram negative, and atypical bacteria including spirochetes and mycoplasma
Inhibits protein synthesis by reversibly binding to 30S ribosomal unit, preventing protein transcription. also believed to alter cytoplasmic membrane permeability; in high doses can inhibit protein synthesis in mammalian cells
has inhibitory properties against the activity of matrix metalloproteinases and can act as a disease modifying agent for osteoarthritis
use with caution in liver and renal dysfunction, pregnancy
Tetracycline susceptibility indicates doxycycline susceptibility; however, the reverse is not true.30,31 Tetracycline-resistant bacteria can be susceptible to doxycycline, necessitating doxycycline susceptibility testing
AE: GI distress, increased liver enzymes can occur, esophagitis, esophageal erosion, strictures possible; staining of developing teeth and bones, photosensitivity,
Drug interactions with divalent or trivalent cations (mineral containing antacids, calcium products, iron products, zinc products)
GI
Minocycline
Bacteriostatic, time dependent
Inhibits protein synthesis by reversibly binding to 30S ribosomal unit, preventing protein transcription. also believed to alter cytoplasmic membrane permeability; in high doses can inhibit protein synthesis in mammalian cells
has inhibitory properties against the activity of matrix metalloproteinases and can act as a disease modifying agent for osteoarthritis
Minocycline can be a useful second tier drug in treatment of canine infections caused by some strains of MRSP
use with caution in liver, may be used in patients with mild to moderate renal insufficiency, pregnancy
Although doxycycline and minocycline are sometimes considered interchangeable, they have differences in pharmacokinetics and antibacterial activity.
AE: GI distress, increased liver enzymes can occur, esophagitis, esophageal erosion, strictures possible; staining of developing teeth and bones, photosensitivity,
