phenicols

what are the important Phenicols in veterinary medicine?

Chloramphenicol

Florfenicol

are Phenicols bacteriostatic or bactericidal?

bacteriostatic, but bactericidal at high concentrations

how do Phenicols work?

they inhibit protein synthesis by binding to the 50s ribosome subunit- preventing transpeptidation

Phenicols are absorbed rapidly and prompty from the _________

upper GI

how are Phenicols distributed within the body?

most bind to plasma proteins, and the free fraction diffuses into almost all tissues (including the brain). they tend to accumulate in tissues

can Phenicols access the CNS?

yes

how are Phenicols metabolized?

liver

what species needs lower doses of Phenicols? why?

cats, because they have a genetic deficiency in glucuronyl transferase activity, which leads to longer plasma half lives

why must we take caution when administering Phenicols in cats?

because they have a genetic deficiency in glucuronyl transferase that leads to longer plasma half lives of the drug

how do Phenicols affect other drugs?

they prolong the duration of action of other drugs, because they are non-competitive microsomal enzyme inhibitors

what adverse reactions might be caused by Phenicols?

-bone marrow suppression

-irreversible aplastic anemia

-GI disturbances with oral chloramphenicol

which Phenicol is immunosuppressive, and what precautions must be taken because of this?

chloramphenicol

we cannot vaccinate animals while being treated with chloramphenicol

Chloramphenicol is not allowed in what species?

production animals, because it leaves residues that can be toxic to humans

what is the spectrum of activity of Phenicols?

broad:

G+, G- and many anaerobes (Rickettsia, Chlamydia, Bacterioides) , especially effective against Salmonella

how do bacteria gain resistance against Phenicols?

they acetylate the Phenicol, preventing it from binding to the ribosome.

they decrease their permeability.

resistance to Chloramphenicol often develops with resistance to tetracyline, erythromycin, streptomycin, ampicillin, and others

what are the veterinary uses of Phenicols?

systemic and local infections

salmonella and bacterioides

florfenicol- bovine respiratory disease

(chloramphenicol cannot be used in production animals)

what is the clinical use of Florfenicol?

bovine respiratory disease