5. Individual cephalosporins differ in their: a) Antibacterial spectrum and relative potency against specific organism b) Susceptibility to β -lactamases from different organisms c) Pharmacokinetic properties d) Local irritancy on i.m. injection MOA Inhibition of cell wall synthesis
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7. FIRST GENERATION Developed in 1960s Have high activity against Gram +ve but weaker against Gram –ve bacteria Cephalothin -1 st cephalosporin used clinically Active against- streptococci, staphylococci, gonococci meningococci etc.
8. SECOND GENERATION More active against Gram –ve organisms Some members active against anaerobes Cafoxitin - highly resistant to β -lactamases produced by gram –ve bacteria. Used in- surgical infections lung abscess
9. THIRD GENERATION Introduced in 1980s Highly active against gram-ve bacteria All are highly resistant to β -lactamases from gram –ve bacteria Cefotaxime Potent action on aerobic gram-ve as well as gram+ve bacteria Not so active on anaerobes
10. USE Hospital acquired infections Septicaemias Infections in immunocompromised patients FOURTH GENERATION CEPHALOSPORINS Developed in 1990s Highly resistant to β -lactamases Active - P.Aeruginosa and S.aureus
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14. CARBAPENEMS Imipenem Extremely potent & very broad spectrum β -lactam antibiotic Effective against- gram+ve cocci P.aeruginosa anaerobes like- B.fragilis C.difficile Disadvantage - rapid hydrolysis by enzyme dehydropeptidase I Overcome by- giving in combination with cilastatin