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133 Cards in this Set
- Front
- Back
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Sulfonamides are structurally similar to what endogenous compound?
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PABA
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What are Sulfonamides effective against?
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Gp and Gn for UTI's and respiratory infections
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Sulfonamides mimic PABA and inhibit which enzyme?
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dihydropteroate synthase
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Sulfonamides are synergistic when combinded with what class of drugs?
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dihydrofolate reductase inhibitors
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What agent is used with a Sulfonamide for synergy?
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Trimethoprim
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Alone are these agents bacteriostatic or bacteriocidal?
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Alone static, together cidal
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Trimethoprim mechanism
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inhibits DHF reductase (enzyme is present in bacteria and humans)
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Most common use of Sulfamethoxazole
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UTI, Cotrimazole = sulfa + trimeth
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Sulfa drug used in treatment of leprosy along with rifampin
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Dapsone
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long acting sulfa drug
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sulfadoxine 100-230 hr half life
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Toxicity of this drug class may lead to hemolytic reactions in patients with G6PDH deficiency
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Sulfa drugs
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Why is it necessary to give sulfa drugs with lots of fluid?
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to prevent crystallization
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Why shouldnt you give sulfa drugs to infants?
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they can't excrete glucorinate bilirubin which leads to kernicterus
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Example of a flouoroquinolone drug
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Ciprofloxacin
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flouoroquinolone killing kinetics
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exhibit concentration-dependent killing
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flouoroquinolone main treatment
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UTI and travelers diarrhea
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more effective at treating UTI's flouoroquinolone or sulfa+trimeth
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flouoroquinolone
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flouoroquinolones are not effective against?
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MSRA, anaerobic bacteria
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flouoroquinolone mechanism
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blocks topo 2 (dna gyrase), blocks topo 4
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flouoroquinolone static or cidal
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cidal
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Absorption of flouoroquinolones are impaired by.....
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ca, mg, and antacids
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flouoroquinolone toxicities
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p450 interaction
contraindicated with NSAIDs Cartilage damage (flouoroquinolone bone) |
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Two urinary tract antiseptics
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Nitrofurantoin, Methenamine
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Nitrofurantoin use
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UTI's
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Nitrofurantoin activated by?
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bacterial reduction
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Nitrofurantoin mechanism
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free radical damage
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Why isnt Nitrofurantoin effective against pseudomonas and proteus
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These bugs increase urine pH
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Methenamine use
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lower urinary tract sterilization
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Methenamine mechanism
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activated by low pH to yield formaldehyde
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Name a drug used for tetracycline resistance
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Tigecycline which is a glycylcycline
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tetracycline static or cidal
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tetracycline is STatic
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tetracycline mechanism
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accumlates in bacteria not humans,
binds to 30s subunit. Blocks aminoacyl-tRNA buy AT 30, CCELL at 50 |
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tetracycline is impaired by
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food and divalent metals
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Tigecycline route of admin and use
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IV, MRSA and other drug resistant bacteria
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If a patient has renal impairment what adjustment should be made to a tetracycline dose
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it should be lowered
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how are proteus and psuedo resistant to tetracyclines (all)
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express a multidrug transporter
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tetracycline toxicity
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discoloration of teeth, photosensitivity,inhibition of bone growth from ca chealation, fanconi's syndrome
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Aminoglycosides cidal or static
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cidal
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Aminoglycosides kinetics
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concentration dependent killing
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Aminoglycosides half life
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strong postantibiotic effect
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Aminoglycosides effective against
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aerobic gram negative enteric
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Aminoglycosides are synergistic with?
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Blactams
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Aminoglycosides are not effective against
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anaerobics
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Aminoglycosides mechanism
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cause misreading of mRNA after binding to 30s subunit
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Aminoglycosides route of admin
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IV
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Can Aminoglycosides penetrate the CNS
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no
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What do Aminoglycosides require for uptake into bacteria
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O2
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Aminoglycosides dosing schedule
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once daily dosing to prevent toxicity
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Aminoglycosides toxicity
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NOT, nephrotoxicity, ototoxicity, teratogen, neuromuscular blockade
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Chloramphenicol mechanism, static or cidal
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inhibits 50s peptidlytransferase, static
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Chloramphenicol interferes with what in humans?
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mitochondrial ribosomes
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Chloramphenicol toxicity
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bone marrow suppression
aplastic anemia gray baby syndrome (lack udp-glucuronly transferase) |
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Chloramphenicol resistance in bacteria
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plasmid encoded chloramphenicol acetlytransferase prevents binding to ribosome
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-
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-
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-
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-
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Kennedy Bugs
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Kennedy Bugs
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the last two amino acids on the pentapeptide made in the cytosolic phase are?
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D-alanines
"The pentapetide chain ends in a D-ala D-ala terminal amino acid sequence." |
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Peptidoglycansynthetase function and antiobiotic that inhibits it
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Transfers building block pentapeptide to cell wall
Vancomycin |
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Function of transpeptidase and group of antibiotics that blocks this step
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crosslinks sugars on bacterial cell wall
blocked by beta lactams |
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Penicillin mechanism
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Penicillin blocks the reactive site of transpeptidase
It binds permanently and doesn't hydrolyze off so transpeptidase doesn't work. |
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How does Penicillin eventually results in cell lysis?
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blocking transpeptidase will cause the cell to activate autolytic enzymes. It thinks it needs to fix the cell.
This explains why penicillin is cidal and that it only effects growing microorganisms. |
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Beta lactamases function
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hydrolyses beta lactam rings in activating beta lactam antibiotics
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Penicillin G narrow or wide spectrum?
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narrow, so many bugs have beta lactamases
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Penicillin G excreted via?
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kidney rapidly
thus Adjust Penicillin dosage mainly based on RENAL FUNCTION |
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Penicillin G oral absorption high or low?
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low 25%
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Penicillin G vs Penicillin V, which is more acid stable?
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Penicillin V
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major toxicity of Penicillin?
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hypersensitivity reactions,
a rare one is steven johnsons hemolytic anemia thrombocytopenia serum sickness nephropathy |
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Example of a penicillinase resistant penicillin beginning with N
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Nafcillin
use naf for staph |
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Nafcillin is eliminated via?
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bilary excretion
almost all penicillins are renally eliminated except nafcillin |
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Aminopenicillins decribe
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think of them as AMPed up penicillins. They are still sensitive to penicillinase but have wider coverage
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Direction for patients regarding taking Aminopenicillins
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Must take on an empty stomach so many patients get GI distress and stop taking it. Affects gram + and gram -.
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Why is Amoxicillin preferred over Ampicillin
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AmOxicillin has greater oral availability and better effect on GI
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Which drug is used to treat pseudomonas
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piperacillin
only give via.. IV or IM, gastric acid inactivates it also has non-linear pharacokinetics |
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What can be given along with amoxicillin to enhance its spectrum
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clauvanic acid which is a penicillinase inhibitor. Alone it has no activity against bacteria
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What are Cephalosporins?
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beta lactam drugs that are less susceptible to penicillinases, they are bactericidal
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Cephalosporins are excreted primarily via
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Kidney
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What two enzymes does cycloserine inhibit
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Alanine racemase
D-ala,D-ala, synthetase What is its use? G-+ but it has many toxicities |
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Bacitracin mechanism
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inhibits recycling of lipid carrier so the sugar cannot be moved to the membrane
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Two 1st generation Cephalosporins
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Cefazolin
Cephalexin Uses? Rarely a drug of choice Cefazolin is used for prophyllaxis in surgery, Cephalexin has a similar spectrum |
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A second generation cephalosporin and uses
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Cefoxitin
IV, some mixed infections, PID, Lung absess, surgical prophyllaxis |
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Two third generation cephalosporins
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-Ceftriaxone
-Ceftazidime uses both penetrate CNS and are resisitant to many beta lactamases Ceftriaxone - gonorrhea,lyme disease, meningitis Ceftazidime-Pseudo |
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Imipenem-Cilastatin
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Highly resistant to beta lactamases
broken down by dehydropeptidase1 in kidney, so given with Cilastatin serious side effects? seizures |
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Carbapenem beginning with M
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Meropenem
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What Carbapenem can be used in a patient with an allergy to penicillin?
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Aztreonam
limited to aerobic gram N. good for enterobacteracie and pseudo hypersensitivity thrombophlebitis at site of injection adverse effects? |
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This drug inhibits peptidoglycan synthetase
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Vancomycin
Resistance is developed when dala dala is mutated to dala-dlac IV Kidney thrombophlebitis at site of injection chills, fever ototoxicity flushing due to rapid infusion/histamine release mode of admin? excretion? adverse effects? |
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Overall protein synthesis inhibitors are bacterio.....
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static
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Prototype macrolide
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Erythromycin
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Erythromycin mechanism
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binding to a protein (23s) on the 50s portion of the ribosome. Binding in this way will promote dissociation by blocking the translocation of tRNA from the A to the P sites, preventing any movement of the ribosome. If this complex is “stuck” for a while, the ribosome “thinks” that protein synthesis has been completed, and will thus release the incomplete protein
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Erythromycin is used most in what class of bacteria, and why?
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gram + since gp bacteria accumulate 100x more of the drug then gram negative bacteria
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How can the 23s RNA be changed to prevent erythromycin binding.
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methylation
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Other then macrolides what other two classes will bind to 23s RNA
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M = macrolides, L = lincosamides, S = streptogramin B
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application of which mls drug induces methylase resistance
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macrolides
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Erythomycin is excreted via
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bilary excretion
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Macrolides _____ cytochrome P-450
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inhibit
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Erythomycin common cause of non-compliance
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gi upset due to interference with motilin receptors
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Erythomycin interesting side effects
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liver toxicity
hearing loss at high doses . Another “interesting” side effect of erythromycin is the ability to prolong the QT segment with ventricular tachycardia, which usually only occurs in combination with other drugs. eosinophilia |
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Clarithromycin differs from Erythomycin how..
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more stable in acid
well absorbed |
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clarithromycin is metabolized by
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metabolized by the liver, with hepatic disease, dosage reduction may have to occur. eliminated renally
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azithromycin unique property
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Azithromycin can penetrate tissues extremely well
advantages over other macrolides? tolerated orally does not inhibit p450 |
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Telithromycin weird effects
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visual disturbances
exacerbates myasthenia gravis (DEF DON"T GIVE TO A PATIENT WITH MA) reversible hepatic dysfunction Qtc prolongation Its a ketolide, not a macrolide same mechanism as marcolides not a substrate for efflux pumps doesnt induce methlyation |
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How is Clindamycin difference from erythomycin in terms of resistance
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Clindamycin does not induce methlyation of 50s subunit, also it is not a substrate for the marolide efflux pump
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,Clindamycin is excreted via
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urine and bile
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main toxicity of clindamycin
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pseudomembranous colitis
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only instance where vancomycin is given orally
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when it needs to treat pseudomembranous colitis in the GI tract
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metronidazole mechanism
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under anaerobic conditions, the bacterial nitroreductase forms radicals reduction products by reducing the N02 on the drug.These products disrupt the DNA and other macromolecules by forming covalent bonds
basically it forms toxic metabolites that damage DNA |
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Metronidazole use
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anaerobic infections
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Metronidazole toxicity 4
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disulfarim like reaction
metallic taste headache dark urine also it inhibits p450 |
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daptomycin mechanism
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membrane depolarizer
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Linezolid is used for what cases?
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Vancomycin resistant organism
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Linezolid mechanism
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binds to 23s rna and inhibits formation of 70s ribosome
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A woman developed bleeding that required a reduction in her anticoagulant dose while being treated for an infection. Which antibiotic was most likely responsible for this drug interaction?
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Erythromycin, toxic with oral anticoagulants
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A man with a skin infection due to MRSA is treated with a n agent that binds to 23s RNA. Which ADR is associated with this antibiotic?
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Anemia and thrombocytopenia
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Which of the following classes of antibiotics acts by binding reversibly to the 50s ribosome, blocks peptidyl transferase and results in tpreventing translocation from A to P site?
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STREPTOGRAMINS
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An asthmatic patient with a documented allergic skin reaction to ampicillin is hospitalized for treatment of a severe respiratory infection due to pseudomonas aeroginosa. Which is of the following is the best choice for this patient?
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Not piperacillin, because it is a penicillin. The best possible choice is vancomycin, even though not necessarily a MRSA reaction, all the problems are avoided.
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Linezolid adverse reactions
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bone marrow suppression
anemia, thrombocytopenia contraindicated in phenyketonurics optic neuropathy |
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Linezolid drug interactions
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mild mao inhibitor if taken with foods rich in tyramine
may cause serotonin syndrome in drugs with pseduoepherdrine |
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Daptomycin uses
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skin infections from staph a.
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What class of antibiotics, and what class of diuertics potentiate ototoxicity?
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Aminoglycosides and Loop Diuretics
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What class of antibiotics must not be used in children 8yrs or younger?
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Tetracyclines
bone growth inhibition teeth discoloration pregnant women are at risk for hepatic risk |
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Safest of all antibiotics? maybe some GI upset at high does
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the macrolides
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1st generation vs 3rd generation cephalosporins bacterial coverage
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the lower the generation the better gram + coverage, the higher the generation the better gram - coverage.
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Oldest anti-tb agent
cannot enter cells lots of resistance |
streptomycin
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This drug penetrates macrophages, is bactercidal, small mw and inhibits mycolic acid formation
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Isoniazid (INH)
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INH toxicity
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Peripheral Neuropathy
Hepatic Toxicity INH injures neurons and hepatoctyes also rash, fever, jaundice |
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How is INH metabolized
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by NAT2 to INH-Acetylated,
there are both fast and slow acetylaters |
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This drug inhibits RNA polymerase in gp gn and mycobacteria. It is bactericidal in mycobacteria. It has many drug drug interactions.
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Rifampin
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This drug penetrates macrophages, and is active at a pH of 5.5
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Pyrazinamide
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Toxicity of Pyrazinamide
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hepatic, hyperuricemia (gouty arthritis)
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This drug is renally eliminated requireing dose reduction, inhibits arabinosyl transferases
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Ethambutol
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Toxicity of Ethambutol
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Decreased Uric acid excretion
Retrobulbar neuritis - loss of visual acuity/red green color blindness |
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INH decreases hepatic metabolism which can lead to increased levels of this drug
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phenytoin toxicity
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What anti-tb drugs induces p450
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Rifampin
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