Walters -Fluoroquinolones

Question 1

What type of antibiotic is Fluroquinolones

Answer 1

1. Cidal

2. G - and G+ bacteria

Question 2

What is the mechanism of action for gram negative bacteria? What about gram + bacteria?

Answer 2

Gram negative: inhibits DNA gyrase–> cant replicate DNA bc FQ prevent rejoining of DNA (usually unwinds DNA in bacteria)

Gram positive: inhibits topoisomerase IV (an enzyme involved in sep. replicated DNA strands into daughter cells)

Question 3

What is the distinction between Second generation FQ’s and third generation FQ’s. are less active in strep. _____

Answer 3

Second generation FQ’s are LESS active in strep pneumoniae. Third generation FQ’s are MORE reactive and are called Respiratory FQ’s

Question 4

What are the second generation FQs

Answer 4

1. Ciprofloxacin- the best FQ for Gram - activity
2. Ciloxan -opthalmic
3. Cipro HC - otic
4. Ofloxacin

Question 5

What are drug interactions with Cipro?

Answer 5

1. Lowers clearance of theophylline so theophylline levels increase which can cause toxicity
2. Cipro inhibits CYP3A4 and CYP1A2; increases levels of methadone and tizanidine

Question 6

what does increase level of methadone cause

Answer 6

possible respiratory depression

Question 7

what does increase level of tizanidine cause

Answer 7

sedation, hypotension, hallucinations

Question 8

What is the only third generation FQ that is an opthalmic (not respiratory) product

Answer 8

Gatifloxacin

Question 9

What are the third generation FQs?

Answer 9

1. Gemifloxacin
2. Levofloxacin (isomer of Oflaxacin)
3. Moxifloxacin: can prolong QT interval in healthy patients

Question 10

What is side affect of levofloxacin

Answer 10

risk of prolonging Q-T interval in elderly; FDA says there is acute hepatitis and fatal events

Question 11

What is a fourth generation FQ?

Answer 11

Besifloxacin: for bacterial conjunctivitis due to susceptible organisms.

Question 12

What are side effects of Fluoroquinolones

Answer 12

1. phototoxicity: burning, redness, swelling, blisters, rash, and itch
2. arthropathy: damages growing cartilage; Dont use in prepubertal children or if pregnant!
3. Tendon rupture: BBW! over 65 or on steroids; it can occur weeks/months after you discontinue drug
4. Changes in blood sugar; impt for diabetics
5. CNS stimulation; convulsions, anxiety
6. Naseua, vomiting, diarrhea
7. peripheral neuropathy
8. psudomembranous colitis from C. difficile

Question 13

What is C. difficile? what does it cause

Answer 13

can be part of our normal flora, but in presence of Antibiotics it can form a spore to protect itself from antibiotic. Then can reemerge when Ab is gone and can grow without competition for nutrients and can generate 2 exotoxins that can cause intestinal fluid secretion, mucosal injury, inflammation, and bloody diarrhea. A plaque forms that looks like a membrane on the colon mucosa called a pseudomembrane

Question 14

how do you treat pseudomembranous colitis

Answer 14

Fidaxomicin; CIDAL -inhibits RNA polymerase. This and its metabolite have significant post antibiotic activity which might contribute to its CIDAL effect. Side effects include naseua, vomiting, GI hemorrage, anemia and neutropenia.

Question 15

what are drug interactions with FQ

Answer 15

avoid antacids, and iron supplements bc these drugs can chelate with mono and divalent cations thus decreasing absorption of antibiotic.