Cephalosporins antibiotics

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Cephalosporins antibiotics

  1. 1. Content • Introduction and Definition A • Advantage and Disadvantage • SAR • Classification B C • Mechanism of action • Therapeutic uses • Pharmacokinetics • Side effect
  2. 2.  Wide-spectrumβ-lactumbactericidal, chemical properties being similar to the penicillins  Cephamycins : Streptomyces species or are synthetic derivatives produced by substituting oxygen for sulfur (methoxy group) in cephalosporin nucleus.  Cephalosporium acremonium, containing common 7-aminocephalosporanic acid nucleus the
  3. 3. Advantages 1. Non-toxic 2. ↓ risk of allergy. 3. More stable in acidic medium [less ring strain] 4. Higher penicillinase resistance. 5. Good activity ≠ Gve & G+ve Disadvantage 1. Difficult to isolate & purify [with highly polar side chain] 2. Lower potency [less strained ring] 3. ↓ absorbed orally.
  4. 4. Mechanism of action: Cephalosporins are bactericidal and have the same mode of action as other beta-lactam antibiotics (such as penicillin). Cephalosporins disrupt the synthesis of the peptidoglycan layer of bacterial cell walls.  The peptidoglycan layer is important for cell wall structural integrity.
  5. 5. These has been conventionally classified into four generations. Based on Generation system • This is based on chronological sequence of development, but more importantly ,takes into consideration the overall antibacterial spectrum as well as potency. • First-generation cephalosporins are predominantly active against Gram-positive bacteria, and successive generations have increased activity against Gram-negative bacteria (albeit often with reduced activity against Gram-positive organisms).
  6. 6. First generation: Developed in 1960, active against Gm+ weaker on Gm- orgnisms. • Cephalothin: 1st cephalosporin used. (Parenteral) active against: Streptococci, Staphylococci, gonococci, meningococci, C.diptheriae and clostridia. • Cephalexin: Orally active. commonly used. (SPORIDEX) • Cefadroxil: Excellent tissue penetration (cefadrox) Excreted unchanged in urine. Dose adjustment in renal impaired patients. • Cephazolin: Active against klebsiella and E.coli. (Parenteral) Preferred parenteral 1st gen cephalosporin for surgical prophylaxis , (ALCIZONE/ORIZOLIN)
  7. 7. Second generation: • Cefuroxime: Resistant to Gm- beta lactamase (Parenteral) Important use: meningitis caused by H. influenzae, • Cefuroxime axetil: Ester of cefuroxime, effective oral Uses: URTI, LRTI, UTI, skin and soft tissue infection group B streptococci,salmonella, E.coli (CEFTUM,ZOCEF)
  8. 8. Third generation • Broad-spectrum. • Active against Gm- enterobacteriacae. • Some are anti-pseudomal • Resistant to beta-lactamase. Cefotaxim: (TAXIM/OMNATAX)  Prototype of third generation cephalosporin.  Widely distributed in body tissues and fluids, penetrates CSF best when meninges are inflamed. Uses: Aerobic Gm- bacteria infection, poor on anaerobes (B. fragilis), Staphylococci and pseudomonas. prominent indications: meningitis 11
  9. 9. Ceftriaxone: • Longer duration of action. (MONOCEF/CEFERA) • Good CSF penetration. USES: Bacterial meningitis Multi-Resistant typhoid fever Complicated Uniary tract infection Ceftazidime: • Active against pseudomonas. • Burn. 12 (CEFZID/TAZID)
  10. 10. Cefoperazone: (CEFOMYCIN/NOVACIP) • Strong anti-pseudomonal property. • Cidal against S.typhi, B.fragilis. • More susceptible to beta-lactamase. USES: severe urinary, biliary, respiratory, skin-soft tissue infection, meningitis and septicaemia. Cefixime: • • (ORIFIX/TAXIM-O/OMNATAX) Orally active 3rd generation Broad spectrum of action- enterobacteriaceae, H. influenzae, Strep pyogenes. Not active against Staph and Pseudomonas . Cefpodoxim proxetil. (CEPODEM) • Orally active 3rd generation • Active against enterobacteriaceae and streptococci. • Excellent outcome in RTI, UTI and soft-tissue infection. Cefdinir: (SEFDIN/ADCEF) • Orally active • 13 Excellent results in pneumonia,COPD,ENT & skin infections.
  11. 11. Fourth generation: Cefepime: (CEPIME/MEGAPIME) • Highly resistant to beta-lactamase. • Active against pseudomonas and Staph besides host of organisms Uses: Serious life-threatening hospital acquired pneumonia Febrile neutropenia. Bacterremia and septicaemia. Cefpirome: (CEFROM/CEFORTH) • Treatment of serious and resistant hospital acquired infections including septicaemia ,pneumonia. • Covers some Gm+ organisms as well.
  12. 12. Cephalosporins are given parenterally and orally. Extent of binding to plasma protein vary from one to another. e.g. Cefazolin is 80% protein bound ( hence, long t1/2 ) Cephalexin is 10-15% protein bound Relatively lipid insoluble ( like penicillins ) Hence,do not penetrate cells or the CNS, except for third generations. Mostly excreted unchanged by the kidney (glomerular & tubular secretion ), except, ceftazidime & cefoperazone( glomerular) Probenecid slows their elimination and prolong their half-live ( except Ceftazidime & cefoperazone) Half-life 30-90 min; ceftriaxone 4-7 hr
  13. 13. 1. Alternative to penicillin in allergic patients 2. Upper respiratory tract infections and otitis media cefaclor cefuroxime axetil cefixime cefprozil 3. Septicaemia caused by G- bacteria ( P.aeruginosae) A penicillin(eg.Piperacillin/ Ticarcillin) +aminoglycoside OR A cephalosporin(eg. ceftazidime ) + AG 4. Urinary tract infections Cefuroxime, Cefixime . 5. Prophlaxis in surgery Appendectomy ( bowel anaerobes ) eg. Cefoxitin Obstetrical &gynecological, urological, orthopedic procedures, etc ( S. aureus & S. epidermidis ) eg. Cefazoline 6. Meningitis- N. Meningitidis Ceftriaxone Cefotaxime( pref. in neonate)
  14. 14. 1. Hypersensitivity reactions- most common Anaphylaxis, bronchspasm, urticaria Maculopapular rash- more common 2. Nephrotoxicity ; esp. cephradine 3. Thrombophlebitis ( i.v admin. ) 4. Superinfections 5. Diarrhea-oral cephalosporins, cefoperazone, ceftriaxone & moxalactam. 6. cefamandole, moxalactam & cefoperazone may cause: a) bleeding disorders b) Flushing, tachycardia, vomiting with alcohol intake
  15. 15. ^ "cephalosporin" at Dorland's Medical Dictionary ^ "Cephalosporin spectrum of resistance". Retrieved 1 July 2012. ^ Stork CM (2006). "Antibiotics, antifungals, and antivirals". In Nelson LH,
  16. 16. M. Zaharna Clin. Chem. 2009

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