AN OVERVIEW OF CEPHALOSPORINS IN VETERINARY MEDICINE Cephalosporins are wide-spectrum β-lactum bactericidal antibiotics, relatively non-toxic, with the chemical properties being similar to penicillins, but are comparatively more stable to pH,temperature changes and β- lactamases. They were first introduced for clinical use in the 1960s. Cephalosporins are weak acidic drugs produced from Cephalosporium acremonium. Structurewise, they contain a dihydrothiazine ring and a β-lactam ring having the common 7-aminocephalosporanic acid nucleus.Modifications of this acid nucleus and semisynthetic sidechain substitutions produce differences in antibacterial spectra, β-lactamase sensitivities and pharmacokinetic properties. Cephamycins are derived from Streptomyces species or are synthetic derivatives produced by substituting oxygen for sulfur (methoxy group) in the cephalosporin nucleus. (John F Prescott, 2006). The mode of action of cephalosporins being bacterial cell wall synthesis inhibition is similar to that of the penicillins. The site of action of beta-lactam antibiotics is the penicillin-binding proteins (PBPs) on the inner surface of the bacterial cell membrane that are involved in synthesis of the cell wall. In actively growing cells, the
An overview of Pharmacological aspects of cephalosporin class of antibiotics for animal use
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AN OVERVIEW OF CEPHALOSPORINS
IN VETERINARY MEDICINE
Cephalosporins are wide-spectrum β-lactum bactericidal antibiotics, relatively non-
toxic, with the chemical properties being similar to penicillins, but are comparatively
more stable to pH,temperature changes and β-lactamases. They were first introduced for
clinical use in the 1960s.
Cephalosporins are weak acidic drugs produced from Cephalosporium acremonium.
Structurewise, they contain a dihydrothiazine ring and a β-lactam ring having the common
7-aminocephalosporanic acid nucleus.Modifications of this acid nucleus and semisynthetic
sidechain substitutions produce differences in antibacterial spectra, β-lactamase
sensitivities and pharmacokinetic properties. Cephamycins are derived from Streptomyces
species or are synthetic derivatives produced by substituting oxygen for sulfur (methoxy
group) in the cephalosporin nucleus. (John F Prescott, 2006).
The mode of action of cephalosporins being bacterial cell wall synthesis inhibition is
similar to that of the penicillins. The site of action of beta-lactam antibiotics is the
penicillin-binding proteins (PBPs) on the inner surface of the bacterial cell membrane that
are involved in synthesis of the cell wall. In actively growing cells, the cephalosporins bind
to the PBPs within the cell wall and lead to interference in production of cell wall
peptidoglycans resulting in subsequent lysis of the cell in an isoosmotic environment. The
differences in affinity for the types of PBPs by different beta-lactam antibiotics and the
bacterial defense mechanisms explain the variations in bactericidal activity among
cephalosporins. (Donowitz GR and Mandell GL, 1988). Major adverse reactions to
cephalosporins are also similar to those experienced with penicillin. The free base acid
stable forms of cephalosporins are used for oral administration and sodium salt derivatives
are used for parenteral administration. Cephalosporins are well distributed in to most of the
body fluids and tissues such as the kidneys, lungs, joints, bone and biliary tract. However,
with the exception of some of the third generation agents, they penetrate poorly in to the
CSF.
Classification: Cephalosporins have been originally classified into three generations based
primarily on their spectrum of antibacterial activity (Caprile KA, 1988). An expanded
classification has been developed on the basis of antimicrobial activity, including β-lactamase
stability and pharmacological properties (Wise, 1997).
Generationwise, from first to fourth, the spectrum of activity against gram negative
organisms and the stability against β-lactamase increase commonly together with the same
or reduced spectrum of activity against gram positive organisms ,with the exception of fourth
generation agents, which have enhanced activity against gram positive ones. Some of the more
recently developed cephalosporins which may not easily fit into anyone of the generations are
usually included in the generation to which their antibacterial properties most closely
resemble. Most of the cephalosporins are usually active against beta haemolytic streptococci
and against beta lactamse producing staphylococci. Methicillin resistant Staphylococcus,
Mycobacteria and Enterococci spp are resistant to all cephalosporins.
Generation
Spectrum of activityGram Gram + ve -ve
β-lactamase stability
Examples
Oral Parenteral
First + + + + + CephalexinCefadroxilCefadrineCephradineCephaloglycin
Cattle Ceftiofur SC route Local ear swelling, may develop a transciently drooping ear, medication leakage or bleeding from the site just after injection
Strict SC, Hygiene,Aseptic administration
Incompatibilities: The admixture of any cephalosporin with other medications in the
same syrienge is not recommended. The admixture of beta-lactam antibacterials (penicillins
and cephalosporins) and aminoglycosides may result in substantial mutual inactivation and
therefore should not be mixed in the same syrienge, intravenous bag or bottle.
Laboratory value alterations : There may be alteration in the laboratory values of
the patient receiving cephalosporin therapy. Some of the laboratory values affected were 1.
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