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Pharmacology of Cephalosporins : General Overview. Flavio Guzmán, M.D. http://pharmamotion.com.ar. β - lactams : cell wall inhibitors. β -lactam ring. The β - lactam ring is a common structure for : Penicillins Cephalosporins Monobactams Carbapenems
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Pharmacology of Cephalosporins:General Overview Flavio Guzmán, M.D. http://pharmamotion.com.ar
β-lactam ring • Theβ-lactam ring is a commonstructurefor: • Penicillins • Cephalosporins • Monobactams • Carbapenems • Bacteria will target this ring togainresistance.
Cellwallinhibitors: importantfeatures • Cellwallinhibitorshavebacericidaleffect. • Theyactsinergisticallywithamynoglycosides • Time-dependentkinetics: the more time thedrugbindsthe bacteria, the more effectiveitis.
Mechanism of action 1 • Beta-lactams bind PBP (Penicillin Binding Proteins). • Some PBP havetranspeptidaseactivity. • Transpeptidaseactivityisessential in cellwallsynthesis.
Chemicalstructure of cephalosporins • Derived from 7-aminocephalosporanic acid. • They suffer the “attack” of bacteria at their beta-lactam ring.
1st Generationcephalosporins: antibacterialcoverage Active mainly against Gram positive cocci. Less active against Gram negative.
2nd generationcephalosporins. Antibioticcoverage Increased coverage against Gram negatives, while keeping coverage against Gram +.
3rd generationcephalosporinsCoverage Increased coverage against Gram negatives. Decreased coverage against Gram +
4th generationcephalosporinsAntibacterialcoverage Coverage against Gram + and Gram -, good activity against β-lactamase producing bacteria.