Fluoroquinolones Flashcards
What is the first-generation fluoroquinolone?
norfloxacin, which has the least activity against both gram-negative and gram-positive organisms.
What is an example of a second-generation fluoroquinolone?
Ciprofloxacin (Cipro XR)
What are examples of third-generation fluoroquinolones?
Levofloxacin (Levaquin) and moxifloxacin (Avelox)
Which fluoroquinolones are used ophthalmically?
Gatifloxacin (Zymar) and ofloxacin (Ocuflox)
What is the mechanism of action of fluoroquinolones?
inhibit bacterial DNA synthesis by being bactericidal.
Which enzymes do fluoroquinolones inhibit in bacteria?
inhibit bacterial topoisomerase IV (in gram-positive bacteria) and DNA gyrase (in gram-negative bacteria).
What is the function of topoisomerase IV and DNA gyrase?
Both enzymes nick and reseal DNA during DNA synthesis to relieve positive supercoils and allow DNA separation during cell division.
How well are fluoroquinolones absorbed orally?
are well absorbed orally, with 80-95% bioavailability.
What can impair the absorption of fluoroquinolones?
impaired by di- and trivalent cations (e.g., calcium, magnesium, aluminum), found in calcium supplements and antacids. It’s recommended to take fluoroquinolones 2 hours before or 4 hours after such substances.
How are fluoroquinolones distributed in the body?
widely distributed in tissues and fluids, including prostatic tissue, but have poor penetration into the cerebrospinal fluid (CSF).
How is ciprofloxacin and levofloxacin eliminated from the body?
eliminated through the kidneys (~70%), so renal impairment can cause longer half-lives.
Why is moxifloxacin not used for urinary tract infections (UTIs)?
undergoes significant hepatic metabolism and fecal excretion, making it ineffective for UTIs.
What is the half-life of ciprofloxacin, levofloxacin, and moxifloxacin?
Ciprofloxacin: 3-5 hours
Levofloxacin: 6-8 hours
Moxifloxacin: 12 hours
Fluoroquinolones gastrointestinal side effects?
2% to 15% experience gastrointestinal upset.
Fluoroquinolones CNS side effects?
Insomnia, headache (~1-2%), tremor, seizures (rare).
Fluoroquinolones tendon side effects?
Tendonitis, Achilles’ tendon rupture (<1%), FDA boxed warning.
Fluoroquinolones skin side effects?
Skin rash and phototoxicity (uncommon).
Can Fluoroquinolones cause peripheral neuropathy?
Yes
Risk of aorta rupture with fluoroquinolones?
Rare risk of rupture or tear of the aorta.
Fluoroquinolones and QT interval?
Prolonged QT interval, rare but potentially lethal in individuals with arrhythmia.
Fluoroquinolones and myasthenia gravis?
May exacerbate muscle weakness, FDA boxed warning.
Are fluoroquinolones safe for children and pregnant women?
Not recommended unless benefits outweigh risks due to potential bone and cartilage development impairment.
Fluoroquinolones and Clostridium difficile?
Associated with Clostridium difficile infection.
How does ciprofloxacin affect CYP1A2?
inhibits CYP1A2, increasing levels of drugs metabolized by CYP1A2.
