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22 Cards in this Set
- Front
- Back
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Name some Macrolides
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Erythromycin, clarithromycin, azithromycin. |
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What is the mechanism of action of macrolides? |
They bind to 50S subunit of bacterial ribosomes, inhibiting translocation |
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How is the effect of macrolides? |
Bacteriostatic |
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How is the mechanism of resistance against macrolides? |
Resistance is often encoded by a plasmid. It can be mediated by: - Drug efflux - Enzymatic inactivation - Changing binding-site of macrolides on the ribosomes |
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Pharmacokinetics of Erythromycin? |
- It is not acid stable, so food intake interferes with absorption. - CYP3A4 inhibitor |
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Adverse effects of macrolides? |
- Prolonged QT - Hepatotoxicity - GI symptoms |
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Where does clarithromycin accumulate and why is this good? |
It accumulates in the middle ear, and is very effective for treatment of otitis media. |
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Where does azithromycin accumulate and why is it beneficial? |
In macrophages. It gets carried to the site of infection. |
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Clinical use of macrolides? |
- In patients allergic to penicillins due to similar spectrum. - Against atypical pneumonia caused by mycoplasma, legionella and chlamydophila. |
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Name some aminoglycosides |
Gentamycin, streptomycin, tobramycin, neomycin, spectinomycin, amikacin |
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Mechanism of action of aminoglycosides? |
Aminoglycosides penetrate the outer membrane of gram- through porin channels, and go through the cytoplasmic membrane by secondary transport. The latter depends on oxygen and pH. Inside the cell, they bind to 30S ribosomal subunit, inhibiting protein synthesis and induce misreading. |
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Common mechanisms of resistance against aminoglycosides? |
- Enzymatic deactivation by cytoplasmic enzymes (most common) - Decreased penetration or changing the binding site of the aminoglycoside on the 30S subunit. |
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How is the effect of aminoglycosides? |
The effect is concentration-dependent, so higher doses kills more bacteria. They are bacteriocidal and have a postantibiotic effect where there is suppression of bacterial growth after treatment. |
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Where do aminoglycosides accumulate? |
In inner ear and the kidney
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How is the dosing with aminoglycosides? |
Dose should be calculated based on body weight or decrease in GFR in renal failure. The effectiveness depends on maximum serum concentration. |
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What are the adverse effects of aminoglycosides? |
- Nephrotoxic - Ototoxic, damaging vestibulocochlear nerve - Neuromuscular blockade with paralysis in patients with myasthenia gravis or for those who take calcium channel blockers and peripheral muscle relaxants. |
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Clinical use of Amikacin? |
Used to treat aminoglycoside-resistant bacteria. |
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Clinical use of gentamycin? |
First choice for sepsis with unknown microbe and focus, together with beta-lactams. |
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Clinical use of neomycin? |
Used topically or given orally to eliminate gut bacteria before a surgery.Is very toxic. |
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What does spectinomycin treat and why is it beneficial? |
Resistant cases of gonorrhea. It is not ototoxic or nephrotoxic like the other aminoglycosides. |
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Clinical use of Streptomycin? |
Second-line drug against tuberculosis |
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Clinical use of Tobramycin? |
Used against pseudomonas. |
