Phenicols Flashcards
what are the physicochemical properties of phenicols?
very lipid soluble with high volumes of distribution
what is the distribution of phenicols?
penetrate intracellularly and widely distributed
do phenicols cross the blood brain barrier?
yes
how are phenicols metabolized?
majority hepatic metabolism
P450 enzyme inhibitor
what is the mechanism of action of phenicols?
inhibition of protein synthesis at the 50S ribosomal subunit
mostly bacteriostatic
what is the efficacy of phenicols dependent on?
time above MIC
for as much of interval as possible
who is chloramphenicol used in?
dogs: tablet or capsule
horses commonly
who is florfenicol used in?
beef cattle
what drug can be effective against enterococcal infections?
chlorampheenicol
what is an adverse effect of chloramphenicol in primates (including humans)?
fatal aplastic anemia
does fatal aplastic anemia occur with florfenicol?
no
how common is fatal aplastic anemia in primates?
1 in every 25,000 to 60,000 patients
what can florfenicol cause in horses?
severe diarrhea and colitis
what can long-term use of phenicols lead to?
bone marrow suppression
reversible upon discontinuation of the drug
why are phenicols prone to drug interactions?
inhibition of P450 enzyme system
who should we be cautious in using phenicols in?
cats
pregnancy
neonates except foals: excreted well into milk as well
is chloramphenicol banned in all food animal use?
yes
do phenicols cross the blood brain barrier?
yes
do phenicols concentrate well in urine (parent drug)?
not well enough for UTIs
what is florfenicol used in beef cattle for?
repository
bovine respiratory disease and foot rot
what is the four quadrant coverage of chloramphenicol?
E. coli: +
Staphylococcus: +
Steptococcus: +
anaerobe: +
outside of the four quadrants, what does chloramphenicol/phenicols work against?
B. fragilis: +
Chlamydia: +/-
Mycoplasma: +
Rickettsia: +
how bad is aplastic anemia caused by chloramphenicol?
fatal without a bone marrow transplant
is fatal aplastic anemia from chloramphenicol dose dependent?
no
can you use phenicols in horses?
florfenicol no
chloramphenicol yes
