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Common Antibiotics |
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Penicillins ¨ Interfere with bacterial cell wall synthesis ¨ Excreted via urine ¨ Poor CNS penetration unless meninges inflamed ¨ Allergy e.g. rashes/ anaphylaxis (encephalopathy) ¨ If allergic to one penicillin, will be allergic to another ¨ Diarrhoea, especially ampicillin which may precipitate pseudomembraneous colitis
Penicillin G ¨ Inactivated by penicillinases ¨ Useful for streps, meningococci, gas gangrene ¨ IV route only as inactivated by gastric acid ¨ 1.2—2.4g QDS IV
Phenoxymethyl– penicillin ¨ Similar antibacterial spectrum as Pen G ¨ Stable in gastric acid, but absorption can be unpredictable ¨ Effective in strep tonsillitis, URTI in children and continuing on from IV Pen G ¨ Prophylaxis against streps after rheumatic fever and pneumococcus after splenectomy ¨ 500mg P.O QDS
Flucloxacillin ¨ Not inactivated by penicillinases ¨ Major use of penicillin V resistant staph ¨ 250mg QDS PO/IM, 250mg—1g QDS IV
Amoxycillin ¨ Broad spectrum antibiotic, better absorbed than ampicillin ¨ Active against gram +ve and some gram –ve organisms ¨ Inactivated by penicillinases ¨ Rashes in glandular fever ¨ Prophylaxis of infective endocarditis ¨ 250mg QDS PO, 0.25—1g QDS IV and up to 3g PO TDS for up to 24 hours
Metronidazole ¨ Good for anaerobes ¨ Cheap ¨ Reaction with alcohol, breast feeding ¨ Taste, rashes, peripheral neuropathy ¨ 200—400m PO TDS, 1g PR TDS, 500mg IV TDS
Cefuroxime ¨ Broad spectrum 2nd generation cephalosporin ¨ Less susceptible to inactivation by penicillinases than 1st generation ¨ 10% allergy cross-over with penicillin allergic patients ¨ 250mg PO BD, 750mg IV QDS/TDS up to 1.5g initially ¨ Cefaclor 250mg PO TDS
Augmentin ¨ Amoxicillin 250 or 500mg with clavulinic acid 125mg ¨ Active against penicillinases ¨ Useful for cellulites / peri-operative prophylaxis ¨ Jaundice, Steven Johnson syndrome, nephritis ¨ 250/125 or 500/125mg PO TDS, 1.2g TDS IV
Erythromycin ¨ Similar in spectrum to penicillin ¨ Nausea / diarrhoea in higher doses ¨ 250—500mg QDS PO, 1g TDS IV over 20mins
Simple infections in the head and neck region: ¨ Penicillin V ¨ Amoxicillin ¨ Metronidazole
Severe infections/ cellulites: ¨ Cefuroxime QDS / Metronidazole TDS ¨ Augmentin |
