Antibiotic Prescribing During Renal or Hepatic Insufficiency PDF

Criteria of antibiotic choice depends on 1- patient 01 Safety + cost + limiting conditions (hepatic or renal disease) 2- Antibiotic 02 Spectrum + pharmacokinetics ( ability to reach the site of infection) 3-bacteria 03 Resistance to the antibiot...

Criteria of antibiotic choice depends on 1- patient 01 Safety + cost + limiting conditions (hepatic or renal disease) 2- Antibiotic 02 Spectrum + pharmacokinetics ( ability to reach the site of infection) 3-bacteria 03 Resistance to the antibiotic Aminoglycosides : nephrotoxicity- neurotoxicity –ototoxicity Penicillins ,beta-lactams ,quinolones: neurotoxicity (seizures, confusion/encephalopathy) Quinololnes : arrhythmia ,tendon rupture (especially when combined with cortecosteroids) Linezolid myelosuppression – serotonin syndrome Linezolid is a monoamine oxidase inhibitor that may increase the risk of serotonin syndrome Isoniazide : seizures – hepatotoxicity Rifampicin: hepatotoxicity- renal toxicity –hematological toxicity Antibiotic spectrum can kill G +ve and G –ve bacteria kills only G+ve or G –ve  Antibiotic spectrum cont. which antibiotics are narrow spectrum ???? keep in your mind the following word GLAM G= glycoeptides ( G+ve) L= lincosamides ( G+ve) A= aminoglycosides (G-ve) M = macrolides ( G+ve)  Antibiotic spectrum cont. Glycopeptides (vancomycin, teicoplanin) why Glycopeptides has no effect on gram negative?  As it is hydrophilic (cannot pass outer lipid member of g -ve) and bulky can't pass in porins of the membrane  Hydrophilic ?? (As it contains sugar in structure)  Antibiotic spectrum cont. Lincosamides (clindamicin ,lincomycin) bacteriostatic also are hydrophillic and bulky so cannot pass inside G-ve bacterial cell but has an effect on anaerobes so used for dental and vaginal infections  11 Antibiotic spectrum cont. Macrolides (erythromycin ,clarithromicin ,azithromicin ,roxithromycin) bacteriostatic  active against some G-ve bacteria but mainly G+ve action  12 Antibiotic spectrum cont. Aminoglycosides (gentamicin, amikacin, tobramycin, neomycin, and streptomycin)  Active against G-ve bacteria ,but To kill G+ve it needs help from another cell wall acting drug (penicillin)  Bacteriostatic VS bactericidal  For most infections, bacteriostatic and bactericidal antibiotics inhibit/kill organisms at the same rate, and should not be a factor in antibiotic selection.  Antibiotic can be cidal against certain bacteria and static against other example linezolid static against staph.aureus hile cidal against str.pneumonia.  Bactericidal antibiotics have an advantage in certain infections, such endocarditis, meningitis, and febrile leukopenia, but there are exceptions even in these cases. Antibiotics prescribing during renal or hepatic insufficiency 01 Examples on antibiotics that are renally eliminated : Most b-lactams with or without b-lactamase inhibitors- Aminoglycosides -TMP–SMX-Azthreonam-Vancomycin- Ciprofloxacin-Levofloxacin-Gatifloxacin-gemifloxacin Antibiotics prescribing during renal or hepatic insufficiency cont.  In case of hepatic impairment : give another renally eliminated 02 alternative with similar spectrum ??? why Examples on antibiotics that are hepatically eliminated : Cefoperazone- Ceftriaxone- Doxycycline –Minocycline- Moxifloxacin-Macrolides-Nafcillin-Clindamycin-Isoniazid Ethambutol-Rifampin-Metronidazole-Tigecycline-Linezolid Antibiotics prescribing during renal or hepatic insufficiency cont. 03 Empiric VS definitive antibiotic therapy 1  Empiric therapy depends on clinical experience of the clinician ( he know the possible causative microorganisms and 1 2 take the decision depending on knowledge) 3 4 2 Definitive therapy depends on sample culture results ‫‪Invitro susceptibility testing‬‬ ‫معلومه مهمه جدا جدا وبتعمل صدام كبير بين بعض الصيادله واألطباء‬ the answer is of course NO why ???? Because the antibiotic concentration is different in invitro isolated samples than invivo sites  example to understand : 1-klebsiella pneumoniae from CSF give sensitive to cefazolin while cefazolin is unable to pass BBB to reach klebsiella site 2- culture of E-coli may give resistant to unasyn although it is active due to high unasyn concentrations in urine (site of E-coli) ‫عشان كده مش دايما المزرعه صح وممكن تالقي الطبيب له رأي مخالف وفي هذه الحاله من حقك‬  Pharmacokinetics of the antibiotic Ability to penetrate tissues to reach site of infection (cefazolin example) Bioavailability is important factor during oral therapy Examples of antibiotics with poor bioavailability Vancomycin –Acyclovir- Cefdinir- Cefditoren Nitazoxanide- (without food)- Fosfomycin  Pharmacokinetics of the antibiotic Antibiotic Penetration limitations 1 abscess ( drainage is a must) 2 Foreign body-related infection 3 Protected focus e.g., cerebrospinal fluid 4 Organ hypoperfusion/diminished blood supply  Duration of antibiotic Therapy In most bacterial infections 1–2 weeks is sufficient. Certain conditions require longer treatment duration such as 1- weak immunity e.g., diabetes, SLE, alcoholic liver disease, neutropenia, diminished splenic function, 2-chronic bacterial infections e.g., endocarditis, osteomyelitis.  Duration of antibiotic Therapy cont. take care excessive antibiotic exposure without clinical reason negatively affect host (bacterial resistance) I like it as an overfilled mobile battery Mechanism of action of antibiotics Sulfonamides inhibit Folate Synthesis SulFOnamide and FOlate contain “FO”. 27 By Fluoroquinolones quintuplets have identical copies of DNA (DNA replication). “QUIN” in fluoroQUINolones and QUINtuplets to remember DNA replication inhibition. By Macrolides, aminoglycosides, lincosamides, and tetracyclines all inhibit protein synthesis. “MALT” malt powder that is sometimes found in “protein” shakes. To remember Macrolides, Aminoglycosides Lincosamides, and Tetracyclines (MALT). By exclusion penicillins, cephalosporins, carbapenems, and glycopeptides inhibit cell wall synthesis: THANK YOU