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24 Cards in this Set
- Front
- Back
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chloramphenicol
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50s protein inhibitor
broad spectrum bacteriostatic inhibits peptidyl transferase (Peptide bond) resistance through acetyltransferases that inactivate drug adverse effects: gastrointestinal disturbances bone marrow suppression gray baby syndrome (young infants don't possess sufficient glucuronidation or renal function to eliminate drug - drug accumulates and inhibits mitochondrial fucntion - cyanosis) |
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aminoglycosides
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30s protein inhibitor
used for gram- rod infections bactericidial enter bacteria via oxygen dependent active transport mechanism mostly effective against aerobic organisms inibits protein synthesis by: blockade of initiation complex misreading of mRNA code * block of translocation antibacterial synergy when used with cell wall inhibitors (penicilin) adverse effects: ototoxicity, involving vestibular (balance) and cochlear (hearing) nephrotoxicity rare, curare-like neuromuscular blockage |
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macrolides
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50s protine synthesis inhibitor
erythromycin, clarithromycin, azitrhomycin (improved erythromycin) inhibits translocation of protein synthesis effective against same organisms as penicillins (substitue: allergy to penicillin) enchance destruction of bacteria (accumulate in macrophages) extensively metabolized; concentrated and excreted in bile adverse effects: GI effects, contraindications in patients with low hepatic function, inhibits CYP3A (potential accumulation of other drugs) |
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clindamycin
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lincosamide that functions in a similar fashion as macrolides
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fluoroquinolones (ciprofloxacin)
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nuclei acid inhibitors
bactericidial; low activity vs. anaerobes inhibits DNA replication by inhibiting DNA gyrase (topoisomerase II) - blocks relaxation of supercoiled DNA required for DNA transcription/duplication avoid using in young, pregnant b/c of data showing some erosion of cartilate* |
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metronidazole (flagyl)
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DNA synthesis inhibitor
mostly active vs anaerobic bacteria AND certian aquatic portozoa (bever fever) -reduced form of drug disrupts DNA structure side effects: nausea, vertigo, metallic taste in mouth disulfiram like effect (like cephalosporin) |
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Nitrofurantion (Macrobid)
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DNA synthesis inhibitor
anaerobic reduced form inactivates or alters baterial ribosomal proteins and other macromolecules (vital biochemical processes - protein synthesis, metabolism, DNA synthesis, etc.) are inhibited. mostly used in urinary tract infections just know: disrupts DNA synthesis + used for urinary tract infection |
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polymixins
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cell membrane inhibitor
cationic, detergent like properties interact with and disrupt phospholipids in cell membranes selective; gram - used topically or injected into caviities |
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Antibiotic resistance
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variety of resistance leads to antibiotic resistance
1. enzymatic destruction of drug (b-lactamases) 2. prevention of prenetration of drug (penicillin) 3. alteration of drug's target site 4. rapid ejection of drug (ABC transporters) |
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Antimicrobials:
Inhibitors of Metabolism sulfonamides (sulphamethoxazole) |
Folate Antagonists
sulfonamides structurally related to PABA bacteria can't absorb folic acid (must synthesize it); sulfonamides compete with PABA for enzyme dihydropteroate synthetase which makes folic acid. used in conjuction with trimethoprim |
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Bacterial resistance of Sulpha Drugs
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altered target enzyme (mutation in enzyme)
increaesd drug inactivation increaesd PABA synthesis |
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sulphasalazine
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Folate Antagonists
sulfonamides not orally absorbed (unlike other sulpha drugs) treats inflammatory bowel disease |
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Sulpha drugs inactivation and side effects
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metabolized by acetylation and elimination by the kidney
potential to precipitate at low urine pH side effects: crystalluria and nephrotoxicity hypersensitivity (rashes) - alleric rxn kernicterus (binding to albumin can displace other drugs or bilirubin) |
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trimethoprim
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Folate Antagonists
inhibitor of bacterial dihydrofolate reductase 20-50x potent than sulphonamides used in combination with sulphonamides. |
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co-trimoxazole
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trimethoprim + sulphamethoxzole
synergistic effect -careful if patient is deficient in folate -used in urinary tract, prostate and respiratory infections |
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penicillins
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penicillin G (benzylpenicillin)
susceptible to b-lactamases poorly absorbed; acid labile (gastirc acid) - IV penicillin V good absorbtion via GI tract but less potent |
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b-lactamase resistant penicillins
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cloxacillin, methicillin
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Extended spectrum penicillins
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amoxicillin (+ clavulanic acid)
penicillinase susceptible Penicillins vs Pseudomonas piperacillin (+tazobactam) |
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probenecid
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usually excretion (of penicillin) via kidney using tubular secretion
-probenecid inhibits this secretion and increases duration of action |
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cephalosprorins
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cephalexin, cefprozil, cefotaxime, cefepime
most IV, well distributed only 3rd gen. reaches CSF (cerebrospinal fluid) eliminated unchanged in urine adverse effects allergy produce disulfiram-like effect block aldehyde dehydrogenase (therefore do no take with alcohol) |
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carbapenems
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cell wall inhibitors
broadest spectrum of all b-lactams ex. imipenem penicillinase-resistant cleaved in kideny tubule by dihydropeptidase which gives toxic metabolites; often given with cilastatin (inhibition of DHP) |
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vancomycin
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cell wall inhibitor
glycopeptide antibiotic bactericidal used to treat MSRA organisms (methicillin-resistant Staph aureus). given IV (can't ingest a protein -glycopeptide) binds to peptides of peptidoglycan monomers; blocks formation of glycosidic bonds and peptide cross links adverse effects: fever, chills, rashes, 'red-man syndrome' resistance by VRE (vancomycin resistant enterococci) |
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bacitracin (polysporin)
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cell wall inhibitor
prevents peptidoglycan monomers synthesized in cytosol from being transported across cytoplasmic membranes polypeptide antibiotic inhibits recycling of lipid carrier use restricted to topical applications (skin, eye, nose, mouth) b/c serious toxic effects on kidney. |
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tetracycline
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30s protein synthesis inhibitor
broad spectrum antibiotic bacteriostatic -blocks binding of aminoacyl-tRNA accumulated via active transport proteins in bacterial membranes -widespread resistance incomplete absorption after oral administration absorption is decreased with milk, antacids, iron due to chelation/preciptation of drug undergo enterohepatic recycling (drug in bile to colon but transported back up ; drug lasts longers) binds to tissue undergoing calcification adverse effects: gastric/intestinal irritation risk of superinfections stained teeth; bone deform. (children) photosensitivity |
