MACROLIDES AND OTHER
ANTIBIOTICS
MACROLIDE ANTIBIOTICS
• Group of antibiotics with a
macrocyclic lactone
structure to which one or
more deoxy sugars are
at...
Macrolides: Erythromycin
• It was isolated from Streptomyces erythreus in 1952
• It was the first of these drugs to find c...
Erythromycin: Mechanism of action
• Bacteriostatic at low but cidal at high concentrations
• Cidal action also depends on ...
Erythromycin: Resistance
• Becoming a serious problem
• Several mechanisms are:
– Inability of organism to take up the ant...
Pharmacokinetics
• Erythromycin base is acid labile but all others (newer)
are stable
• Given as enteric coated tablets
• ...
Pharmacokinetics

Cont…

• Concentrates in liver
• Inflammation allows greater tissue penetration
• 70-80% plasma protein ...
Adverse effects
• Epigastric distress
• Cholistatic jaundice
• Ototoxicity (at high doses)
• Hypersensitivity
Interactions
Uses
• As an alternative to pencillin
– Strep. Inf, Diptheria, Tetanus, Syphylis and Gonorrhoea

• As a first choice drug ...
Roxithromycin
• Acid stable
• Good enteral absorption and tissue
penetration
• 95% plasma protein bound
• Has longer half ...
Clarithromycin
• Acid stable
• Bioavailability is 50% due to first pass metabolism
• Follows zero order kinetics
• Longer ...
Azithromycin
• Extended spectrum
• Better tolerability
• More active against H.influenza but less active
against gram poss...
Other antibiotics
Clindamycin
• Mechanism of action is same as that of erythromycin
• Resistant mechanisms are same as those of
erythromycin...
Clindamycin

Cont…

• Absorption is good
• Distributes well but not to CSF and brain
• Excreted in urine and bile
• Plasma...
Clindamycin

Cont…

Adverse effects:
• Skin rashes
• Diarrhoea and pseudomembranous entero colitis
(C.difficile)
Vancomycin
• Glycopeptide antibiotic
• Discovered in 1956 as a pencillin substitute
• Effective against MRSA, Strep.virida...
Vancomycin
Pharmacokinetics:
• No absorption from oral route
• Slow IV infusion is employed for treatment of
systemic infe...
Vancomycin
Adverse effects:
• Fever, chills, phlebitis at the infusion site
• Flushing (red man syndrome)
• Dose related h...
Linezolid
• Was introduced recently to combat resistant
gram possitive organisms such as:
– MRSA and VRSA
– VR enterococcu...
Linezolid

Cont…

Mech of action:
• Inhibits bacterial protein synthesis by inhibiting the
formation of 70s initiation com...
Linezolid
Restance:
• Decreased binding to the target site confers
resistance
Pharmacokinetics:
• Completely absorbed on o...
Linezolid

Cont…

Side effects:
• Well tolerated
• GI upset, nausea, diarrhoea, headache and rash
• Thrombocytopenia (2%)
Polypeptide Antibiotics
• Low molecular weight cationic polypeptide antibiotics
• All are powerful bactericidal agents
• N...
8. macrolides and others
8. macrolides and others
8. macrolides and others
8. macrolides and others
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  • Transcript of "8. macrolides and others"

    1. 1. MACROLIDES AND OTHER ANTIBIOTICS
    2. 2. MACROLIDE ANTIBIOTICS • Group of antibiotics with a macrocyclic lactone structure to which one or more deoxy sugars are attached • In 1950 the first drug of this class was isolated: Picromycin • In 1952 Erythromycin and Carbomycin were introduced into clinic. O CH3 H3C HO CH3 HO N H3C H3C H3C O O O O O CH3 Picromycin CH3 CH3
    3. 3. Macrolides: Erythromycin • It was isolated from Streptomyces erythreus in 1952 • It was the first of these drugs to find clinical application, both as a drug of choice and an alternative to penicillin in individuals who are allergic to β-lactam antibiotics • Slightly water soluble • Macrolides are stable in aqueous solutions at or below room temperature. They are unstable in acidic or basic conditions or at high temperatures.
    4. 4. Erythromycin: Mechanism of action • Bacteriostatic at low but cidal at high concentrations • Cidal action also depends on the organism and its rate of multiplication • More active in alkaline medium • Acts by inhibiting bacterial protein synthesis • Bind irreversibly to a site on the 50s subunit of the ribosome and interferes with ‘translocation’
    5. 5. Erythromycin: Resistance • Becoming a serious problem • Several mechanisms are: – Inability of organism to take up the antibiotic or presence of efflux pump – Decreased affinity – Presence of plasmid associated erythromycin esterase • Both clarithromycin and azithromycin show cross resistance with erythromycin • But telithromycin can be effective against macrolideresistant organisms
    6. 6. Pharmacokinetics • Erythromycin base is acid labile but all others (newer) are stable • Given as enteric coated tablets • Food delays absorption by retarding gastric emptying • Its acid esters are better absorbed • Widely distributed in the body except CSF • Diffuses into prostatic fluid, accumulates in macrophages
    7. 7. Pharmacokinetics Cont… • Concentrates in liver • Inflammation allows greater tissue penetration • 70-80% plasma protein bound • Partly metabolized and excreted primarily in the active form (some enterohepatic circulation) • Renal excretion is minor (5%) • Its plasma t1/2 is 1.5hr, but it persists longer in tissues
    8. 8. Adverse effects • Epigastric distress • Cholistatic jaundice • Ototoxicity (at high doses) • Hypersensitivity
    9. 9. Interactions
    10. 10. Uses • As an alternative to pencillin – Strep. Inf, Diptheria, Tetanus, Syphylis and Gonorrhoea • As a first choice drug for: – Atypical pneumania – Whooping cough – Chancroid • As a second drug choice: – – – – Campylobactor enteritis Legionnaire’s pneumonia Chlamydia trachomitis Pencillin resistant Staphylococcal infections
    11. 11. Roxithromycin • Acid stable • Good enteral absorption and tissue penetration • 95% plasma protein bound • Has longer half life 12hrs
    12. 12. Clarithromycin • Acid stable • Bioavailability is 50% due to first pass metabolism • Follows zero order kinetics • Longer half life (3-6hrs), its metabolite is also active • Antibacterial spectrum is wider: – Micobacterium avium complex – M. leprae – Toxoplasma gondii
    13. 13. Azithromycin • Extended spectrum • Better tolerability • More active against H.influenza but less active against gram possitive cocci • Rapidly absorbed from empty stomach • Longest half life (3days) • Spectrum is identical to clarithromycin, except that it is less active against Staphylococci and Streptococci
    14. 14. Other antibiotics
    15. 15. Clindamycin • Mechanism of action is same as that of erythromycin • Resistant mechanisms are same as those of erythromycin • It inhibits most of the gram possitive cocci • Highly active against a vareity of anaerobes, specially B. fragilis • Aerobic gram negative bacilli are not effective
    16. 16. Clindamycin Cont… • Absorption is good • Distributes well but not to CSF and brain • Excreted in urine and bile • Plasma half life is 3hrs
    17. 17. Clindamycin Cont… Adverse effects: • Skin rashes • Diarrhoea and pseudomembranous entero colitis (C.difficile)
    18. 18. Vancomycin • Glycopeptide antibiotic • Discovered in 1956 as a pencillin substitute • Effective against MRSA, Strep.viridans, enterococci and clost.difficile • Acts by inhibiting cell wall phospholipid synthesis as well as peptidoglycon polymerization (transglycolation step)
    19. 19. Vancomycin Pharmacokinetics: • No absorption from oral route • Slow IV infusion is employed for treatment of systemic infections or for prophylaxis • Metabolism is minimal • 90-100% excreted through glomeruar filtration Cont…
    20. 20. Vancomycin Adverse effects: • Fever, chills, phlebitis at the infusion site • Flushing (red man syndrome) • Dose related hearing loss Cont…
    21. 21. Linezolid • Was introduced recently to combat resistant gram possitive organisms such as: – MRSA and VRSA – VR enterococcus faecium, E. faecalis – Pencillin resistant streptococci
    22. 22. Linezolid Cont… Mech of action: • Inhibits bacterial protein synthesis by inhibiting the formation of 70s initiation complex
    23. 23. Linezolid Restance: • Decreased binding to the target site confers resistance Pharmacokinetics: • Completely absorbed on oral administration • IV preparations also available • Widely distributed throughout the body • Partly metabolized non enzymatically • Excreted in urine • Plasma half life is 5hrs Cont…
    24. 24. Linezolid Cont… Side effects: • Well tolerated • GI upset, nausea, diarrhoea, headache and rash • Thrombocytopenia (2%)
    25. 25. Polypeptide Antibiotics • Low molecular weight cationic polypeptide antibiotics • All are powerful bactericidal agents • Not used systemically due to toxicity • All are produced by bacteria • Clinically used ones are: – Polymyxin B – Colistin – Bacitracin
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