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71 Cards in this Set
- Front
- Back
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What are the three components of a penicillin drug?
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1) Thiazolide ring
2) Beta-Lactam ring 3) Secondary amino group (side chain) |
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What is the significance of the beta-lactam ring?
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1) Essential for biological activity of penicillin
2) If cleaved, the product lacks activity 3) Adding side chains or combining with beta-lactamase inhibitors can protect the ring. |
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What is the significance of the secondary amino group?
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Determine the pharmacologic and anti-bacterial properties.
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What do PBP's do?
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They catalyze the transpeptidase reaction that forms cross links between peptides.
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What is the mechanism of action for beta-lactam antibiotics?
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-Structural analogs of the substrate for PBP's
-Bind to PBP active site preventing peptidoglycan synthesis. |
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Beta-lactam drugs are only bactericidal if
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The bacteria are actively growing and synthesizing cell wall.
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What is the MIC?
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Minimum concentration of antibiotic to inhibit bacterial growth. (Minimum Inhibitory Concentration)
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Do beta-lactams exhibit time dependent killing?
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Yes; depends on presence of sustained concentrations of active drug above MIC
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What are four mechanisms of resistance to Beta-lactams?
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1) Inactivation of antibiotics by beta-lactamases
2) Modification of target PBPs 3) Impaired penetration of drug to target PBP's (G-) 4) Presence of an efflux pump (G-) |
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What are two organisms that produce beta-lactamases which hydrolyze penicillins? (Meaning this is their mechanism of resistance to penicillin)
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E. coli and Staph aureus
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What organism produces beta-lactamases which hydrolyze cephalosporins and penicillins?
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Pseudomonas aeruginosa
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What is pneumococci's mechanism of resistance to penicillins?
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Modification of target PBP
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What is Staph's mechanism of resistance to methicillin?
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Modification of target PBP
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What two factors affect the absorption of penicillins?
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Acid stability and protein binding.
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Most penicillins (except amoxicillin) should be what?
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separated from a meal by one to two hours.
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Why are IV penicillins preferred over IM?
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irritation and pain with IM
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What are two penicillins that are formulated to delay absorption and provide prolonged blood and tissue concentration.
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benzathine and procaine.
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What are the only penicillins suitable for oral use?
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1) PCN VK
2) Dicloxacillin/Cloxacillin 3) Ampicillin/Amoxicillin |
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Which tissues cannot be penetrated by penicillins?
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eye, prostate and CNS
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Can oral penicillin agents penetrate bone?
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NO!!!!!!!!!!!!!!!!
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What is the method of elimination for most penicillins?
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renal baby!
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What is the method of elimination for Nafcillin?
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Biliary
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What is the method of elimination for oxacillin, dicloxacillin and cloxacillin and what does this mean in terms of dosing?
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Renal AND biliary so no renal adjustment is necessary.
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Ureidopenicillins like piperacillin has what kind of excretion?
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20-30% biliary so less renal adjustment is needed for renal dysfunction.
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Most penicillins have what kind of half lives and what does this mean in terms of dosing.
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Short half lives (30-60 min) means more frequent dosing necessary.
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What are the natural penicillins?
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Penicillin G, PCN VK, enzathine and Procaine Penicillin G
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Natural penicillins are generally active against which organisms?
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Gram + (streptococci, enterococci, penicillin susceptible Strep pneumoniae), Gram - cocci (meningococci) and non-beta-lactamase producing anaerobes.
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How is penicillin G given?
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IV
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What is penicillin G used for?
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meninGitis! and endocarditis! (Penicillin G for you and ME-Meningitis and Endocarditis)
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How is PCN VK given?
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orally, poor bioavailability
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What is PCN VK given for?
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Throat infections, respiratory tract infections, soft tissue infections
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What are the uses for Benzathine and Procaine Penicillin G?
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IM injection for pneumonia and gonorrhea but not used anymore since most strains are resistant.
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WHat are the penicillinase-resistant penicillins?
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methicillin, nafcillin, oxacillin, cloxacillin, dicloxacillin
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What are penicillinase resistant penicillins active against?
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Staph and strep. These drugs are resistant to staph beta-lactamases due to a side chain hence their name
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Penicillinase resistant penicillins are NOT active against? And why?
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enterococci, anaerobes and Gram - cocci and rods. They produce a new PBP.
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Why is methicillin no longer used?
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nephrotoxicity
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Nafcillin and oxacillin are the drug of choice for what? What is the caveat?
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Staph infections? Use vanco for empiric treatment until susceptibility is determined.
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What are the main classes of extended spectrum penicillins?
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Aminopenicillins, carboxypenicillins and ureidopenicillins
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Extended spectrum penicillins have what kind of activity?
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Improved activity against Gram - organisms due to enhanced ability to penetrate Gram - outer membrane.
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Are extended spectrum penicillins inactivated by beta-lactamases?
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YES!!!!!!!!!
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Name the two aminopenicillins?
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Ampicillin and amoxicillin.
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The aminopenicillins are the first group of penicillins with what?
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activity against Gram- organisms.
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How is ampicillin given?
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IV
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What is the spectrum of action for ampicillin?
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used IV for serious infections with anaerobes, enterococci, Listeria, Gram -bacilli (E. coli and H. flu)
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What is ampicillin NOT active against?
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Pseudomonas, Klebsiella, Enterobacter, Citrobacter, Serratia
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How is amoxicillin given usually?
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Orally-better oral absorption.
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What is amoxicillin active against?
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Same stuff as ampicillin: anaerobes, enterococci,Listeria, E. coli, H. flu...
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What are some uses for amoxicillin?
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sinusitis, otitis, lower respiratory tract infections.
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Which drug has replaced PCN VK as the drug of choice for prophylaxis for endocarditis prior to dental procedures?
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Amoxicillin!!!!!!!!!!!!!!!!!!!!!!
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Name a carboxypenillin.
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Ticarcillin
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What is Ticarcillin's spectrum of action?
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Covers PSEUDOMONAS and enterbacter. Less active against enterococci, DOES NOT COVER KLEBSIELLA!
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What are two very significant adverse effects associated with Ticarcillin?
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Prolonged bleeding time due to platelet dysfunction and hypokalemia.
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Name a Uriedopenicillin
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Piperacillin
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What is the spectrum of action of Piperacillin?
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Covers Pseudomonas, Enterobacter, Klebsiella
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What is piperacillin used for?
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In combo with aminoglycoside against Pseudomonas; used for pneumonia, bacteremia, UTI's, osteomyelitis and soft tissue infections.
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What are beta-lactamase inhibitors used for?
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To extend the activity of penicillins. (like beta-lactamase producing strains of staph aureus)
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What is the mechanism of action for beta-lactamase inhibitors?
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irreversibly bind to the catalytic site of beta-lactamase; also bind to PBP/s and increase the activity of the antibiotic
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What are four penicillin/beta-lactamase inhibitor combinations?
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amoxicillin/clavulinic acid, ampicillin/sulbactam, ticarcillin/clavilinic acid, piperacillin/tazobactam
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What is amoxicillin/clavulinic acid active against?
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Meth susceptible Staph Aureus, H. flu, Klebsiella, bacteroides
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What is the activity of ampicillin/sulbactam
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Meth susceptible Staph Aureus, H. flu, Klebsiella, bacteroides. This drug is available IV!
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What is the activity of Ticarcillin/Clavulinic Acid?
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Extends spectrum of ticarcillin to include Klebsiella, covers stenotrophomonas maltophilia
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What is the activity of piperacillin/tazobactam?
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MSSA, H. flu, Klebsiella, Bacteroides fragilis, and more activity against G+ and G-
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What are the only penicillins that cover Pseudomonas?
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Ticarcillin and Piperacillin (extended spectrum) and PIP/Tazo
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What percentage of the population has reported hypersensitivity to penicillins?
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3-10%
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What causes hypersensitivity to penicillins?
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the degradation products; hypersensitivity is directly proportional to the duration and total dose of penicillin.
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True or false: there is cross allergenicity between natural and synthetic penicillins?
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TRUE!!!!!!!!!!!!!
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What are some types of allergic reactions to penicillins?
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Anaphylaxis (rare), serum sickness, skin rashes, oral lesions, fever, hemolytic anemia. **Patients can be desensitized with increasing doses of peniclllin
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Ampicillin is associated with a rash in what condition that is not due to allergy to the meds?
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MONO
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What is an important bowel related adverse effect of penicllins?
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C. diff entercolitis!
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What are two very significant side effects associated with caboxypenicillins?
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hypokalemia, platelet dysfuntion
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What is a major side effect of piperacillin?
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neutropenia
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