Tetracyclines Flashcards
What is a notable side effect of expired tetracyclines?
Nephrotoxicity
Others include: 1st trimester teratogen, hepatotoxicity in women and female dogs ONLY, GI flora disruption, tissue necrosis at injection site.
How do tetracyclines work?
Protein synthesis inhibition at the 30S ribosomal subunit.
What are some mechanisms of resistance to tetracyclines?
Resistance is plasma mediated.
Reduced penetration, active efflux, alterations to bacterial ribosome, and enzymatic degredation of the drug.
What are the non-antibiotic effects of tetracyclines?
Inhibit collagenase, anti-inflamm, oxytetracycline - relax contracted tendons in foals/calves
What do tetracyclines work on?
Strep, Chlamydia, Rickettsia, Lepto, and Mycoplasma.
WILL CLEAR CARRIER STATE IN LEPTO!
Drug of choice for Rocky Mtn Spotted Fever, Erlichia, Lyme.
Can use for kennel cough and pink eye.
Can be used for E. coli, but NOT without susceptibility testing first!
How are tetracyclines absorbed?
Oral absorption varies, and food decreases bioavailability. Older tetracyclines should NOT be used in horses due to GI flora disruption. Dairy products and antacids will prevent oral absorption.
Are tetracyclines lipid or water soluble?
Doxycycline and minocycline are more lipid soluble and cross BBB. Tetracyclines have intracellular distribution.
How are tetracyclines eliminated?
Renal AND hepatic. Enterohepatic recirculation. Doxy elim is mostly hepatic.
Are tetracyclines time or concentration dependent?
Time dependent
Are tetracyclines bactericidal or bacteriostatic?
Bacteriostatic.
Chlortetracycline:
Only used as feed additive in food animals.
Tetracycline HCL:
Small animals (capsule/liquid) and chickens (water additive)
Oxytetracycline:
Primary injectable. 4 formulations. GIven IV or IM - IM has sustained release effect.
Doxycycline:
Can be used orally in horses. Preferred tetracycline in small animals. Better membrane penetration.
Minocycline:
Similar to Doxy.
