Exam 2: Fluoroquinolones Flashcards
What are the 6 drugs in the fluoroquinolone class?
Ciprofloxacin, ofloxacin, Levofloxacin, moxifloxacin, gatifloxacin, and gemifloxacin
What is the MOA of fluoroquinolones?
Inhibition of DNA grasses prevents the relaxation of positively supercoiled DNA that is required of normal transcription and replication.
- Inhibition of Topo IV interferes with separation of replications chromosomes to daughter cells
- Bactericidal
What is the spectrum of fluoroquinolones?
Primarily effective against G- rods, with good G+ coverage.
-Moxi and gemifloxacin are effective against anaerobes.
Which fluoroquinolone is used to treat UTIs?
Ciprofloxacin
How are fluoroquinolones excreted?
Renally, but can be blocked by probenecid
Which fluoroquinolone is used to treat prostatitis?
Ofloxacin
What are the adverse effects of fluoroquinolones?
GI disturbance, prolonged QT interval, Cartilage erosion, tendon rupture, and photosensitivity
What are the contraindications of fluoroquinolones?
Pregnancy, nursing women, and children under 18
What is the MOA of metronidazole?
It is a prodrug that is non-enzymatically reduced by reacting with reduced ferredoxin. Metabolites are taken up into bacterial DNA and form unstable molecules.
-Bacteriocidal
What is the spectrum of metronidazole?
Potent antibacterial activity against G+ and G- ANAEROBES
What is metronidazole indicated for?
Anaerobic or mixed intrabdominal infections , vaginitis, RTI, pseudomembranous colitis (vanco first choice), and endo carditis
-Also part of the combo therapy for H. Pylor
What are the adverse reactions to metronidazole?
Disulfiram like reaction, disgeusia (metallic taste), GI disturbance, CNS and PNS toxicity, and hypersensitivity
What bacteria is responsible for most community acquired infections?
E. Coli
What G+ bacteria causes about 10-15 % of UTIs?
Staphylococcus saprophyticus
What bacteria are responsible for catheter associated UTIs?
Proteus, klebsiella, Serratia, and pseudomonas
What are the 3 important properties of exclusive UTI drugs?
1) renally excreted ( if not, the drug is not going where it needs to go to treat the UTI)
2) Achieve high urinary concentrations, but not therapeutic concentrations anywhere else in the body. Cidal in the urine, concentration dependent
3) Required an acidic environment to be activated
What are the 2 exclusive UTI drugs?
Nitrofurantoin and Methanamine
What is the MOA of Nitrofurantoin?
Damaged bacterial DNA - it is a prodrug reduced in bacterial cells to an intermediate that can attack ribosomal proteins, DNA, and metabolism molecules
What is the spectrum of Nitrofurantoin?
G+, G-, E. Coli, S. Pyogenes, Citrobacter, klebsiella, enterobacter, salmonella, shigella, and Indole positive proteus.
What bacteria are resistant to Nitrofurantoin?
Most proteus and and pseudomonas
When should Nitrofurantoin not be used?
If creatinine clearance is less than 50mL/min. Antibiotic will not reach sufficient levels in urine for antibacterial activity
What patient education should you give when prescribing Nitrofurantoin?
It turns the urine brown
What are the adverse side effects of Nitrofurantoin?
Nausea, vomiting, diarrhea, allergic reactions, hepatocellular damage, hemolytic anemia (in G6PD deficiency), pulmonary fibrosis (with chronic usage), and neurological disorders
What are the contraindications of Nitrofurantoin?
Pregnancy between 38-42 weeks (because babies G6PD status is not yet known) less than one month age, impaired renal function, and allergy.
What is the MOA of methenamine?
Taken orally, this prodrug decomposes to formaldehyde and ammonia in the acid medium fo the urinary tract.
-Bacterial resistance to formaldehyde does not develop
What is the spectrum of methenamine?
Nearly all bacteria are sensitive but those that increase the pH of the urine inhibit the release of formaldehyde (proteus).
Combine with a weak organic acid such as hippuric acid
What are the toxicities associated with methenamine?
Essentially no toxic because little decomposition takes place in the body until it appears in the acidic urine.
Possible to have mild GI distress or allergic reaction
What are the contraindications of methenamine?
- Hepatic insufficiency: conversion to formaldehyde releases ammonia which needs to be converted to urea in the liver, which cannot be done in hepatic deficiency. Can lead to hepatic encephalopathy
- Renal insufficiency: Low urine output
