Chapter 6 inhibitors of cell wall synthesis


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Chapter 6 inhibitors of cell wall synthesis

  1. 1. Inhibitors of Cell Wall Synthesis Penicillin  Natural penicillins  Semisynthetic penicillins  Extended-spectrum penicillins
  2. 2. Penicillins Low toxicity Effective derivatives created from manipulating drug’s basic molecular structure Kills bacteria by preventing them from forming the rigid cell wall Because human cells do not have cell walls, they are not affected
  3. 3. Therapeutic Uses of Penicillins Abscesses Beta-hemolytic streptococcus Meningitis Otitis media Pneumonia Respiratory infections Tooth and gum infections Venereal diseases (syphilis and gonorrhea) Endocarditis due to streptococci
  4. 4. Penicillins’ Side Effects Diarrhea Allergies in 7% to 10% of populationPenicillins’ Dispensing Issues Take on an empty stomach  Food slows absorption  Acids in fruit juices or colas could deactivate the drug
  5. 5. The Structure of Penicillins
  6. 6. The Structure of Penicillins
  7. 7. Retention of Penicillin G
  8. 8. The Effect of Penicillinase onPenicillins
  9. 9. b-Lactam Antibiotics Penicillin  Penicilinase-resistant penicillins  Penicillins + b- lactamase inhibitors Carbapenems  Substitute a C for a S, add a double bond Monobactam  Single ring
  10. 10. Inhibitors of Cell Wall Synthesis Cephalosporins  First-generation: Narrow spectrum, gram- positive  Second-generation: Extended spectrum includes gram-negative  Third-generation: Includes pseudomonads; injected  Fourth-generation: Oral
  11. 11.  First-generation  Similar to penicillinase-resistant penicillins with greater gram-negative coverage  Used for  community-acquired infections  mild to moderate infections Second-generation  Increased activity, especially against Haemophilus influenzae  Used for  Otitis media in children  Respiratory infections  UTIs Third-generation  Active against a wide spectrum of gram-negative organisms  Long half-life, so once-a-day dosing for some  Used for  Ambulatory patients  Children (dosing before or after school)
  12. 12. Inhibitors of Cell Wall Synthesis Polypeptide antibiotics  Bacitracin  Topical application  Against gram-positives  Vancomycin  Glycopeptide  Important "last line" against antibiotic-resistant S. aureus
  13. 13. Comparison of Cephalosporin andPenicillin
  14. 14. The Inhibition of Protein Synthesisby Antibiotics
  15. 15. Inhibitors of Protein Synthesis Chloramphenicol  Broad spectrum  Binds 50S subunit; inhibits peptide bond formation
  16. 16. Inhibitors of Protein Synthesis Aminoglycosides  Streptomycin, neomycin, gentamycin  Broad spectrum  Changes shape of 30S subunit
  17. 17. Inhibitors of Protein Synthesis
  18. 18. Inhibitors of Protein Synthesis Streptogramins  Gram-positives  Binds 50S subunit; inhibits translation
  19. 19. Inhibitors of Protein Synthesis
  20. 20. Inhibitors of Protein Synthesis Oxazolidinones  Linezolid  Gram-positives  Binds 50S subunit; prevents formation of 70S ribosome
  21. 21. Inhibitors of Nucleic Acid Synthesis Rifamycin  Inhibits RNA synthesis  Antituberculosis Quinolones and fluoroquinolones  Nalidixic acid: Urinary infections  Ciprofloxacin  Inhibits DNA gyrase  Urinary tract infections
  22. 22. Quinolones Strong, rapid bactericidal action against most gram- negative and many gram-positive bacteria Antagonize the enzyme responsible for coiling and replicating DNA, causing DNA breakage and cell deathQuinolones’ Dispensing Issues Not to be given with theophylline Antacids interfere with absorption Avoid exposure to sun
  23. 23. Therapeutic Uses of Quinolones Bone and joint infections caused by gram-negative organisms Infectious diarrhea Ophthalmic infections Some sexually transmitted diseases Upper respiratory infections UTIs
  24. 24. Quinolones’ Side Effects Primarily gastrointestinal, with nausea and vomiting Dizziness Unpleasant taste Can cause joint problems such as swelling and malformations Patients taking them have a tendency to injure tendons
  25. 25. Rifamycin any of a family of antibiotics biosynthesized by a strain of Streptomyces mediterranei, effective against a broad spectrum of bacteria, including gram-positive cocci, some gram-negative bacilli, and Mycobacterium tuberculosis and certain other mycobacteria; used for the treatment of tuberculosis and the prophylaxis of meningococcal infections.
  26. 26. Adverse reactions CNS: ataxia, confusion, drowsiness, fatigue, headache, asthenia, psychosis, generalized numbness EENT: conjunctivitis; discolored tears, saliva, and sputum GI: nausea, vomiting, diarrhea, abdominal cramps, dyspepsia, epigastric distress, flatulence, discolored feces, anorexia, sore mouth and tongue, pseudomembranous colitis GU: discolored urine Hematologic: eosinophilia, transient leukopenia , hemolytic anemia, hemolysis, disseminated intravascular coagulation (DIC), thrombocytopenia Hepatic: jaundice Metabolic: hyperuricemia Musculoskeletal: myalgia, joint pain Respiratory: dyspnea, wheezing Skin: flushing, rash, pruritus, discolored sweat, erythema multiforme, toxic epidermal necrolysis, Stevens-Johnson syndrome Other: flulike symptoms, hypersensitivity reactions including vasculitis
  27. 27. prophylaxis refers to medical or public healthmeasures taken in order to prevent disease or healthproblems, rather than to treat or cure an existingcondition. Prophylaxis is also a way to stem anoutbreak of disease, or minimize the symptoms ofsomeone who has been exposed to a disease or virus.