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
-
من كتب طب بيطرى - مكتبة كتب الطب.