Fluoroquinolones Test Questions – Flashcards
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| What are the main QN used? |
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| 1. Ciprofloxacin (Cipro) 2. Levofloxacin (Levaquin) 3. Moxifloxacin (Avelox) 4. Gemifloxacin (Factive) |
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| When QN are combined with Beta lactams, how do you describe the efficacy of the combination? |
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| Additive |
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| Are QN conc dependent or conc independent? |
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| AG and QN are conc dependent |
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| QN are mostly used for what? |
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| Double coverage! |
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| Describe the relationship between AG and QN with nephrotoxicity. |
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| AG and QN both cause nephrotoxicity, however, QN induced nephrotoxicity is not as significant and common as AG - QN are not very soluble and can crystalize and cause tubular necrosis |
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| What is the MOA of QN? |
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| 1. Selectively inhibit Type II Topoisomerase (DNA Gyrase and Topoisomerase IV) |
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| For gram (-) organisms, what is the primary target? |
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| DNA Gyrase |
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| For gram (+) organisms, what is the primary target? |
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| Topoisomerase IV |
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| What happens when you inhibit Topoisomerase IV? |
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| Strand separation problems |
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| What happens when you inhibit DNA Gyrase? |
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| Supercoiling problems |
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| What are we trying to do with the newer QN? |
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| We are starting to manipulate the placement of fluoride to target DNA Gyrase or Topoisomerase IV |
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| How many generations of QN do we have? |
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| 3 generations |
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| What are the enzyme subunit and gene that codes for DNA Gyrase? |
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| GyrA and GyrB |
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| What are the enzyme subunit and gene that codes for Topoisomerase IV? |
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| ParC and ParE |
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| What is the oldest QN? |
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| The oldest QN is CIPRO, then ofloxacin |
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| Cipro dominates which part of the market? |
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| Gram neg: Enterobacter, klebsiella, ecoli (sucks at targeting strep pneumo) |
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| Levoquin dominates which part of the market? |
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| Gram pos (particularly CAP) |
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| What is classified as a normal QN? |
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| Cipro |
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| What is classified as respiratory QN? |
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| Levo, Moxi, Gemi - very selective for CAP bc these drugs are highly potent against strep pneumo which is the most common cause of CAP, COPD exacerbations, sinusitis) Gram (+): Legionella, H. pneumoniae, Chlamydia/Mycoplasma pneumonia |
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| What is the advantage of QN? |
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| They cover atypicals bc not all bacteria have peptidoglycan but all bacteria uses DNA Gyrase or Topoisomerase IV |
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| What is a problem of QN? |
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| One simple mutation is all it takes for resistance |
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| What are the mechanisms of resistance for QN? |
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| 1. Chromosomal - gyrA/B or parC/E mutations - different QN have diff affinity for enzymes - changes in binding affinity = increased MIC - Gram (-) organisms seem to be more gyrA mutation prone 2. Permeability alterations - seems to be mostly observed with gram (-) organisms - the outer cell wall is altered or the porin expression is decreased - QN target is in the cell and drug is unable to reach target or does so at lower than effective levels 3. Efflux - transport QN and other antibiotics out of the cell - associated with low to intermediate resistance |
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| How can you eliminate QN resistance? |
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| By targeting 8-10 times above the MIC, bc these are conc dependent killing however, limited by seizures and nephrotoxicity |
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| What is a disadvantage of PO QN? |
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| QN bind to Ca, VitD, and Mg, so the bioavailability of QN can be decrease when taken along with enteral feedings, antacids, Ensure, milk |
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| How do you decrease resistance to QN? |
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| 1. If initial MIC testing values are elevated, use max tolerated QN dose 2. Limit the use of QN in the animal population 3. Resistance can be eliminated for QN if the drug conc is 8-10x the MIC 4. Avoid interactions that decrease oral F |
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| What is the max MIC killing? |
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| Max killing occurs at 15-20x MIC |
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| Describe the PK of QN? |
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| 1. Widely distributes to most body tissues 2. Cipro, Levo, Moxi obtain good conc in the liver, kidneys, feces, prostate, lungs, sinuses 3. Moxi is 50% metabolized by glucoronidation/sulfate conjugation, high fraction of drug eliminated via feces 4. Tissue conc > plasma 5. High intracellular concentrations |
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| What level of AUIC do you need for gram (+/-) to be effective? |
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| Gram (+): AUIC > 30 Gram (-): AUIC > 125 |
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| What level of AUIC is needed to prevent resistance for gram (+/-)? |
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| Gram (+): AUIC > 50 Gram (-): AUIC > 100 Peak:MIC > 10:1 |
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| Do QN have post-antibiotic effect? |
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| Yes |
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| Which QN is used mostly for UTI? |
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| Cipro and Levo - highest urine conc (Cipro most used when SPACE is suspected) |
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| Ciprofloxacin |
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| 1. Increased Gram (-) coverage |
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| What can't Cipro be used for? |
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| Never recommend Cipro for Pneumococcus |
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| Cipro has poor activity against what? |
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| Cipro is poor against Enterococcus |
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| Cipro is combined with what for intra-abdominal infections? |
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| Cipro + Flagyl |
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| Levo, Moxi, Gemi |
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| Increased (+) coverage: S. pneumoniae, S. aureus - Will work for MSSA, variable activity with MRSA - E. faecalis coverage is good, E. faecium coverage is not reliable (Amp & Gent for E. faecalis) - Listeria coverage is good |
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| Moxifloxacin |
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| 1. Increased anaerobic coverage 2. Some use in intra-abdominal infections 3. Retains gram (+) activity |
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| Gemi and Moxi are mostly used for what? |
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| 1. CAP 2. AECB 3. DRSP CAP |
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| What is the only oral anti-pseudomonal drug? |
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| Cipro! |
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| For serious infections, do you want to use QN? |
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| No |
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| Will QN work for MRSA? |
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| Not really |
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| What options do you have for drug resistant strep pneumo? |
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| 1. Gemi 2. Moxi 3. Ceftriaxone 4. Cefitaxime 5. Ceftaroline |
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| What does QN have poor to moderate activity against? |
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| 1. S. aureus 2. S. epidermidis 3. Resistance to staph develops rapidly 4. MRSA/MRSE coverage overall is rather poor 5. Moderately active in combination for Mycobacterium infections |
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| What does QN have excellent activity against? |
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| 1. Enterobacteriaceae 2. H. ducreyii 3. H. influenza 4. M. catarrhalis 5. Moxi and Gemi have increased Strep activity 6. N. gonorrhea resistance has increased 7. Covers atypicals: Chlamydia, Mycoplasma, Legionella |
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| How do you treat Pseudomonas aeruginosa UTI? |
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| Cipro & Levo are adequate alone |
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| What is the efficacy against PseudomonasWhat are their MIC? |
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| Cipro > Gemi = moxi > Levo MIC Cipro = 4; Gemi = 4-5; Moxi = 8; Levo = 16 |
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| What is the efficacy against S. pneumoniae? |
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| Gemi > Moxi > Levo MIC Gemi < 0.03, Moxi <.25, Levo 1 |
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| What is the efficacy of Staph aureus? |
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| Moxi > Levo |
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| Which QN has efficacy against anearobes? |
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| Moxifloxacin |
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| Which QN can be used for intra-abdominal infections? |
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| Cipro and Moxi but Cipro doesnt have anaerobic cover so must be combined with flagyl |
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| Should QN be combined with AG for double coverage? |
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| NO! No synergy or additive effects |
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| Are QN ADE tolerable? |
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| Yes, QN are rarely d/c bc of ADR |
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| What are the ADR of QN? |
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| 1. GI 2. CNS 3. Dermatologic 4. Renal 5. Arthropathy 6. Tendonitis of Achilles, shoulder & hand 7. Chondrotoxicity 8. Vasculitis 9. Cardiotoxicity prolongation 10. Hypo/hyperglycemia 11. Teratogenicity (Gee, CDR are ATC, VCr Have to be Tossed) |
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| What are DDI's of QN? |
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| 1. Multi-valent cation-containing products: Al, Mg, Ca, Fe, Zn 2. Sucralfate (aluminum gum) 3. Cimetidine (decreases tubular secretion of renally eliminated QN: cipro, levo) 4. Didanosine: Buffered by Al carbonate and MgOH 5. Theophylline/Caffeine (CYP1A2 interaction: Cipro) 6. Warfarin: Cipro/Levo 7. Foscarnet 8. QT prolonging medications - Amiodarone, atypical antipsychotics, TCAs, TKIs |
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| What would you use for complicated Pseudomonal UTI? |
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| Oral Cipro |
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| When would you use QN? |
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| 1. Drug resistant strep pneumo 2. Complicated pseudomonal UTI 3. Prostate infections |
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| What are alternative uses of QN? |
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| 1. Traveler's Diarrhea 2. Osteomyelitis 3. Otitis media 4. Bioterrorism related anthrax post exposure prophylaxis 5. Empiric therapy for severe CAP in a high risk patient or those requiring hospitalization |
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| What are some patient counseling tips? |
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| 1. Finish all medication 2. Minimize UV exposure 3. Hydrate/water 4. Bioavailability issues & arthropathy |
