❞ كتاب Florfenicol ❝

Florfenicol من كتب طب بيطرى

© 2007 The United States Pharmacopeial Convention
All rights reserved
1
FLORFENICOL
(Veterinary—Systemic)
Some commonly used
brand names
for veterinary-labeled products
are:
Aquaflor
and
Nuflor.
Note: For a listing of dosage forms and brand names by country
availability, see the
Dosage Forms
section(s).
Category:
Antibacterial (systemic).
Indications
Note: The text between
EL
US
and
EL
describes uses that are not included
in U.S. product labeling. Text between
EL
CAN
and
EL
describes uses
that are not included in Canadian product labeling.
The
EL
US
or
EL
CAN
designation can signify a lack of product
availability in the country indicated. See the
Dosage Forms
section of this monograph to confirm availability.
General considerations
Florfenicol is a broad-spectrum, pr
imarily bacteriostatic, antibiotic
with a range of activity similar
to that of chloramphenicol,
including many gram-negative and gram-positive organisms;
{R-1}
however, florfenicol does not carry
the risk of inducing human
aplastic anemia that is asso
ciated with chloramphenicol.
{R-13}
Florfenicol has been dem
onstrated to be active
in vitro
and
in vivo
against
Mannheimia (Pasteurella) haemolytica, Pasteurella
multocida,
and
Haemophilus somnus.
{R-1; 2}
In vitro
studies have
demonstrated florfenicol activity against
Enterobacter cloacae,
Escherichia coli, Klebsiella pneumoniae, Salmonella typhi,
and
Shigella dysenteriae
{R-2; 15; 16}
but with at least a 2- to 10-fold
higher minimum inhibitory con
centration than that for the
Mannheimia, Pasteurella
and
Haemophilus
species listed
above.
{R-15; 16}
It also has activity against some chloramphenicol-
resistant strains of bacteria,
{R-17}
possibly because it is less affected
by the major enzyme produced in
plasmid-mediated bacterial
resistance against chloram
phenicol and thiamphenicol.
{R-2; 26}
Although the activity of florfenicol against obligate anaerobes is
not addressed in the literature, it
is likely to be quite effective.
{R-28}
Accepted
EL
CAN
Enteric septicemia (treatment)
EL
—
Catfish:
Florfenicol Type A
medicated article is indicated in
the control of mortality due to
enteric septicemia caused by
susceptible strains of
Edwardsiella
ictaluri
.
{R-36}
EL
US
Furunculosis (treatment)
EL
—
Salmon:
Florfenicol Type A
medicated article is indicated in the treatment of furunculosis
caused by susceptible strains of
Aeromonas salmonicida
.
{R-11}
EL
US
Keratoconjunctivitis, infectious (treatment)
EL
—
Cattle:
Florfenicol
injection is indicated in Canadian product labeling in the
treatment of infectious bovine keratoconjunctivitis caused by
Moraxella bovis.
{R-3; 33; 34}
Pneumonia, bacterial (treatment)—
Cattle:
Florfenicol injection is indicated in the treatment of
bacterial pneumonia and associated respiratory infections
(bovine respiratory disease
complex) in cattle caused by
susceptible
H. somnus, M. haemolytica,
and
P. multocida.
{R-1;
3}
EL
CAN
Florfenicol injection is also indicated in the control of
bacterial pneumonia and associated respiratory disease in
cattle at high risk of developing infection associated with
susceptible
H. somnus, M. haemolytica,
and
P. multocida.
EL
{R-
1; 3; 32}
Pigs
:
EL
CAN
Florfenicol oral solution
EL
and
EL
US
florfenicol injection
EL
are indicated in the treatment of bacterial pneumonia and
associated respiratory infec
tions caused by susceptible
Actinobacillus pleuropneumoniae,
P. multocida,
EL
CAN
Salmonella choleraesuis,
and
Streptococcus suis
Type
2
EL
.
{R-3; 37}
Pododermatitis, infectious (treatment)—
Cattle:
Florfenicol injection is
indicated in the treatment
of infectious pododermatitis
(interdigital phlegmon) asso
ciated with susceptible
Bacteroides
melaninogenicus
and
Fusobacterium necrophorum.
{R-1; 3; 30}
Regulatory Considerations
U.S.—
Withdrawal times have been estab
lished for florfenicol in catfish
and cattle; however, it is not labeled for use in lactating dairy
cattle or in veal calves
(see the
Dosage Forms
section).
{R-1; 36}
Canada—
Withdrawal times have been esta
blished for florfenicol in cattle
and salmon; however, it is not
labeled for use in lactating
dairy cattle
or in veal calves (see the
Dosage Forms
section).
{R-3; 11}
Chemistry
Source:
A fluorinated derivative of thiamphenicol.
{R-12}
Chemical name:
Acetamide, 2,2-dichloro-
N
-[1-(flouromethyl)-2-
hydroxy-2-[4-(methylsulfonyl)phenyl]ethyl]-[
R
-(
R*,S*
)]-.
{R-4}
Molecular formula:
C
12
H
14
C
l2
FNO
4
S.
{R-14}
Molecular weight:
358.21.
{R-4}
Description:
Melting point 153 to 154
̊
C.
{R-12}
Solubility:
Soluble in water.
{R-12; 13}
Lipid soluble.
{R-13}
Pharmacology/Pharmacokinetics
Mechanism of action/Effect:
Florfenicol is a bacteriostatic
antibiotic that inhibits protein synthesis by binding to ribosomal
subunits of susceptible bacteria
, leading to the inhibition of
peptidyl transferase
{R-1; 13; 26}
and thereby preventing the transfer of
amino acids to growing peptide
chains and subsequent protein
formation. The bacterial receptor that is the site of action for
florfenicol is considered to be the same as that for
chloramphenicol and thiamphenicol.
{R-13; 26}
In the treatment of
bovine respiratory disease, florfenicol may be considered
bactericidal against some
Mannheimia
(
Pasteurella) hemolytica
and
Pasteurella multocida
when it is administered to achieve
minimum inhibitory concentrations (MICs);
{R-14}
the minimum
bactericidal concentrations (MBCs) are very close to the MICs.
Florfenicol has a fluorine atom instead of the hydroxyl group located
at C-3 in the structure of ch
loramphenicol and thiamphenicol.
{R-13}
This may allow florfenicol to be
less susceptible to deactivation
by bacteria with plasmid-transm
issible resistance that involves
acetylation of the C-3 hydroxyl
group in chloramphenicol and
thiamphenicol, and prevents th
eir interaction with bacterial
ribosomes.
{R-13; 26}
Other actions/effects:
Florfenicol, like thiamphenicol, lacks the
nitro group located on the chloramphenicol aromatic ring that has
been associated with
chloramphenicol-induced, non–dose-related,
irreversible aplastic anemia in people.
{R-13; 24; 25}
However,
chloramphenicol and thiamphenico
l also cause a dose-dependent,
reversible bone marrow suppression in some animals and
people
{R-13}
due to mitochondrial injury.
{R-24}
It is theoretically
possible that florfenicol coul
d cause some dose-dependent,
reversible bone marrow suppression, but it has not been clinically
reported.
{R-13}
Absorption:
Bioavailability—
Intramuscular administration:
Calves,
3 to 6 months of age—78.5% (range 59.3 to 106%),
with a dose of 20 mg per kg of body weight (mg/kg).
{R-1;
2; 8}
Cattle,
lactating—38
±
14%, with a dose of 20 mg/kg.
{R-9}
Horses
—81%, with a dose of 22 mg/kg
-
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