Tetracyclines Flashcards
tetracyclines bind very strongly with divalent and trivalent metal ions to form ______________________ which can interfere with drug dissolution and bioavailability
insoluble complexes
what happens with divalent cations orally?
chelate and prevent oral absorption
how are tetracyclines eliminated?
renal and hepatic
tetracyclines bind to the 30S ribosomal subunit. what does this do?
inhibits protein synthesis
prevents addition of amino acids to a growing peptide chain
what tetracyclines are more lipid soluble and cross most barriers, including the blood brain barrier?
doxycycline and minocycline
how common is cross-resistance within tetracyclines?
common
what are the common tetracycline agents?
chlortetracycline
oxytetracycline
tetracycline
doxycycline
what is the spectrum like with tetracyclines?
one of broadest
great deal of resistance exists for many common bacterial pathogens
what is the primary injectable tetracycline in veterinary medicine?
oxytetracycline
what is the preferred tetracycline in small animal?
doxycycline
what is the drug of choice for tick-borne disease and Leptospirosis?
doxycycline
what is a common adverse effect of tetracyclines?
gastrointestinal floral disruption
why is doxycycline used to treat Leptospirosis?
to clear renal carrier state
what is a unique adverse effect of doxycycline?
hepatotoxicity
sudden collapse following _________________________ is one adverse effect of tetracyclines
rapid IV administration
what can tablets of doxycycline cause in cats?
esophageal ulcers/strictures
who should you not use IV doxycycline in?
equine: cardiac arrhythmias, collapse, death
what things are divalent cations?
dairy products and antacids
what decreases the bioavailability of tetracyclines?
food: 60% decrease
what is the distribution of tetracyclines?
vary by agent
what is the distribution of doxycyclines and minocycline?
lipid soluble: cross most barriers, including blood brain barrier
what is resistance of tetracyclines mediated by?
plasmids
what determines the efficacy of tetracyclines?
time-dependent maybe
are tetracyclines bacteriostatic or bactericidal?
bacteriostatic
what is a less commonly used tetracycline?
minocycline
is there a lot of resistance with tetracyclines?
yes
what is the four quadrant coverage of tetracyclines?
E. coli: -
Staphylococcus: *
Streptococcus: *
anaerobes: *
what do tetracyclines work for that are not in the four quadrants?
Chlamydia
Rickettsia
Leptospirosis
Mycoplasma
what is the distribution like of doxycylcine?
more lipid soluble: better barrier penetration, including prostate and blood brain barrier
what drug is used during initial Leptospirosis stabilization?
ampicillin because it is cheaper than doxycycline
does ampicillin or doxycycline have better tissue penetration?
doxycycline
what do all of the tetracyclines except for doxycycline cause as an adverse effect?
staining of teeth from in utero exposure or exposure prior to eruption of adult teeth
what is a unique adverse effect of tetracyclines for cats?
esophageal strictures/ulcers
tablets: doxycycline
what drug is not safe to use IV in horses?
doxycycline
cardiac arrhythmias, collapse, death