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35 Cards in this Set
- Front
- Back
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What makes these antibiotics selective?
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Bacteria have 70$ ribisomes whereas mammalian cells have 80$ ribosomes.
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Where does Linezolid bind and what does it prevent?
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Linezolid (an oxazoladinone) bind the 50$ and prevents formation of the initiation complex.
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Where do Tetracyclines bind and what does they prevent?
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Tetracyclines bind the 30$ and prevent binding of aminoacyl tRNA.
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Where do aminoglycosides bind and what does they prevent?
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Aminoglycosides bind the 30$ and interfere with the initiation complex and cause MISREADING of mRNA.
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Where does Chloramphenicol bind and what does it prevent?
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Chloramphenicol binds 50$ and inhibits PEPTIDYL TRANSFERASE.
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Where do Macrolides, Lincosamides, typeB Streptogramins and Ketolides bind and what does they prevent?
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These drugs bind 50$ and inhibit TRANSLOCATION.
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What is one antibiotic combination to avoid?
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Because of the close proximity of the binding between Chloramphenicol, Clindamycin and Macrolides, binding of one may block the binding of others.
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What action does the Oxazolidinone LINEZOLID have?
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Binds 50$, prevents formation of initiation complex.
Bacteriostatic for G+, also a weak nonspecific MAOI (caution in people taking seritonergics) |
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What action do the Tetracyclines have?
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Broad Spectrum bacteriostatic activity against G +/- aerobic & anaerobic bacteria.
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Name the tetracyclines.
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Tetracycline, Doxycycline and Minocycline.
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Whats up with doxycycline and minocycline?
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They have more lipophilic substituents and are most active by weight. This is because the absorption of these drugs is not impaired by food, as in all the other tetracyclines.
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What are the adverse effects of Tetracyclines?
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Crosses the placenta. Tx of pregnant women or kids< 8 yo will result in discolored teeth and bone deformation.
IM administration causes painful local irritation. |
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What are the aminoglycosides?
(8) |
Streptomycin
Neomycine Gentamycin Kanamycin Tobramycin Sisomycin Amikacin Netilmicin |
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What is the action of the Aminoglycosides?
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They bind the 30$ subunit and interfere with the initiation complex, cause misreading and premature chain termination.
Broad bactericidal activity, primarily against G- bacteria. |
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What about the pharmacokinetics of the aminoglycosides?
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They have a significant PAE.
In G- bacteria, the drugs cross the outer membrane via a PORIN channel and cross the inner membrane by O2 dependent active transport. SYNERGISM occurs when administered with Beta-lactam antibiotics. |
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What are the adverse effects of the aminoglycosides?
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Ototoxicity
Nephrotoxicity Curare-like neuromuscular blockade w high doses |
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What is the action of Chloramphenicol?
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Broad spectrum, bacteriostatic for most bacteria, bacterioCIDAL for meningeal pathogens.
Binds 50$ and inhibits peptidyl transferase. |
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What are the adverse effects of Chloramphenicol?
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Direct effects on bone marrow: Dose realted normocytic anemia and idiosyncratic blood dyscrasias including APLASTIC ANEMIA!
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What is Gray baby syndrome?
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Gray baby syndrome- vomiting, flaccidity, hypothermia, resp distress, gray pallor and shock (40%fatality)
mechanism: inadequate glucuronic acid conjugation and inadequate renal excretion of the unconjugated drug. |
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What is the MLS group of antibiotics?
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Macrolides, Lincosamide, and Type B Streptogramin. Ketolide was recently added to this group aswell.
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What are the Macrolides?
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Erythromycin, Clarithromycin, and Azithromycin
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What action do the macrolides have?
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They bind the 50$ subunit and inhibit the translocation step of protein synthesis.
They are usually bacteriostatic, but can be bacteriCIDAL in high concentrations. |
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What is the unique mechanism of macrolide resistance?
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Production of a methylase (enzyme know as MLSb determinant) that modifies the ribosomal target, leading to decreased drug binding.
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What about hepatic enzymes and the macrolides?
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Erythro- and clarithro-(but not azithro) inhibit hepatic enzymes.
Erythro- interactions with liver p450's inhibits the metabolism of a variety of other drugs. |
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Adverse effects of the macrolides?
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GI, hepatic and CARDIAC (arrythmias- QT prolongation w VT)
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What is the only Lincosamide we study and what is its action?
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Clindamycin.
a congener of lincomycin that has improved pharmacokinetics and less toxicity. Binds 50$ and inhibits translocation step. |
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What is the spectrum for the Lincosamide clindamycin?
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Broad spectrum, G+ cocci. Good for anaerobes like B Fragilis, clostridium.
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Adverse effects of clindamycin?
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GI-modification of GI flora can cause pseudomembranous colitis assoc w overgrowth of C. Difficile
NM blockiing Skin Rashes- more common in HIV pts |
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What are the Type B Streptogramins?
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Synecid is a combination of Streptogramin A (DALFOPRISTIN) and Streptogramin B (QUINUPRISTIN).
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How do the Streptogramins work?
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Strep B QUINUPRISTIN- binds 50$ inhibits translocation step.
Strep A DALFOPRISTIN- induces a conformational change in 50$ subunit, ENHANCING the binding of quinupristin (strep B) |
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Spectrum of Streptogramins?
Side Effects? |
BacteriCIDAL against G+
Pain and phlebitis at site of infusion. |
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What Ketolide are we studying?
Whats its action? |
Telithromycin
same binding to 50$ and inhibition of translocation as macrolides BUT is resistant to efflux pumps and has increased ribosomal binding affinity |
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Why is Telithromycin so cool?
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Recently apporved (April 26 2004) it is especially useful in tx of drug resistant respiratory infections.
Used in community aquired pneumonia, acute sinusitis, acute exacerbations of chronic bronchitis and tonsillitis/pharyngitis |
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What are the side effects of Telithromycin?
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similar to macrolides, GI sxs, dizziness and headache.
Telithromycin also inhibits p450 enzyme (CYP34A) and increased serum concentrations of certain drugs. |
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Which 2 MLS are resistant to efflux pumps?
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Telithromycin (ketolide) and Clindamycin (lincosamide)
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