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24 Cards in this Set
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Aminoglycosides pharmacokinetics (admin, distrib, elim, protein binding)
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Admin - Not absorbed well, IV/IM
Distrib - No CNS penetration Elim - via kidney unchanged Protein - Very little binding |
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Aminoglycosides Mech
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Cidal. Bind to 30s ribosomal subunit preventing protein synth. Also cause misreading of mRNA leading to translation of a mutant protein which becomes a pore which disrupts the cell membrane and can cause death.
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Aminoglycoside Spectrum
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Used for aerobic G- bacilli, staph, and certain mycobacteria. (only aerobic b/c entrance into cell is an active process requireing O2)
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Aminoglycoside Resistance
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1) Modification of enzymes that inactivate aminoglycosides (major mech). Adenyltransferase, acetyltransferase, phosphotransferase.
2) Altered ribosomal binding site 3) Altered aminoglycoside uptake |
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Aminoglycosides Side effects
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Nephrotoxicity - Major one. accumulation leads to proximal tubular damage of kidneys. Will see dark brown casts in urine.
Ototoxicity - Vestibular and auditory. Irreversible, risk factors include length of therapy, repeated exposre, loop diuretics, increased age, renal probs. NM blockade, inhibit presynaptic release of Ach and decreased post syn sensitivity. |
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Streptomycin (class, spectrum, side effects)
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Class: Aminoglycoside
Spectrum: Used alone for TB, used with penicillin for strep, enterococci, tularemia, plague, brucellosis SE: Hypersensitivity, Ototoxicity, less nephrotox than other aminos |
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Gentamicin (class, spectrum, side effects)
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Class: Aminoglycoside, is the workhorse
Spectrum: Aerobic G-, pseudomonas, kelbsiela, Serratia. Strep and pneumococci are resistant. SE: Ototox is worst. Is also the most nephrotoxic amino, |
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Tobramycin (class, spectrum, side effects)
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Similar to gentamicin but costs more and is better against pseudomonas. Also less toxic.
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Kanamycin (class, spectrum, side effects)
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Class: Aminoglycoside
Spectrum: No longer used in U.S. Used topically. Used against some G- and pre-surgery. SE: Oto and nephro, and cause super infection if used to sterilize bowel pre surgery. |
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Amikacin (class, spectrum, side effects)
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Class: aminoglycoside
Spectrum: Broadest spectrum, useful in hospitals, has a resistance to many enzymes which break it down, therefore saved for reserve for real bad cases. Works on pseudomonas. SE: Oto and nephro with emphasis on auditory. |
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Neomycin (class, spectrum, side effects)
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Class: Aminoglycoside
Spectrum: Broad, good for + and - but to toxic for systemic use; only topical. Used to sterilize bowel pre surgery and for burns, wounds, and ulcers. SE: Hypersensitivity when topical, severe oto and nephro when taken systemically, superinfection if taken to sterilize bowel. |
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Tetracycline pharmacokinetics (Admin, Distrib, Elim, protein bound)
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Admin: Well absorbed in SI, can be given orally. Absorb impaired by food, divalent cations, dairy, and antacid. Doxo and minocyclin are unaffected.
Distrib: Well, crosses placenta, enters CNS. Elim: Most are metabolized and excreted by kidneys. Doxycycline almost all feces. Impaired liver function is a contraindication (kidney is fine). Protein: Is bound to protein. |
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Tetracycline mech
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Static. Binds to 30s subunit inhibiting protein synth. Never given in combo with penicillin b/c is staitc.
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Tetracycline Resistance
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Plasmid encodes for proteins which interfere with its active uptake and pumps which pump out the antibiotic. Resistance to one is usually resistance to all.
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Tetracyclenes Side effects
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Never give to children before they have their permanent teeth (or pregnant women) or they will be brown and discolored.
Some have photox. Hypersensitivity - Can cause pruritis and vaginitis in addition to usual. GI Liver |
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2 main types of tetracyclene super infections
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Staph entercolitis and pseudomembranous colitis caused by C. difficile
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Tetracyclene Spectrum
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Static. Better at treating G-. Can treat G+ cocci First choice for:
Rickettsia Mycoplasma Chlamydia Brucellosis Cholera Plague Lyme disease. Alternative for: Clostridium, Leptospira, Actinomyces, resp infections, acne. |
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Tetracyclenes examples and key side effects
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Demecocycline and Minocycline cause phototoxcicity in addition to general SEs. All tetracyclenes end in -cyclene.
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Chloramphenicol pharmakokinetics (admin, distrib, elim, protein)
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Admin: Can be given orally
Distrib: Enters CNS as well as placenta and breast milk Elim: Inactivated by glucuronidation and p450 in liver. Counterindicated if hepatic failure. Metabolism can be induced or inhibited. Protein: Yes, 50% is bound. |
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Chloramphenicol Mech
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Static but cidal to H. influenzae. Binds to 50s subunit preventing protein synth.
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Chloramphenicol resistance
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Occurs via induction of acetyltransferase which acetylate and inactivates the Ab.
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Chloramphenicol Side Effects
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Irreversible aplastic anemia - Most important SE. While rare, leads to bone marrow depression and is up to100% fatal (why its not commonly used)
Reversible decreased iron and hemaglobin content Hypersensitivity In neonates, can cause gray baby syndrome - grey color, vomiting, feeding probs, rapid resp., cyanosis. |
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Chloramphenicol Spectrum
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Broad bu only usually used if there is a resistance to tetracyclenes:
Meningitis Typhoid fever Abscesses Rocky Mountain Brucellosis |
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Chloramphenicol drug interactions
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Can inhibit microsomal enzymes which biotransform other drugs. Can also increase the half-life and [] of drugs bound to albumin like warfarin.
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