Fluoroquinolones

Question 1

Code for
A) second line FQ’s
B) first line FQ’s

Answer 1

A) LGMP
B) NCPO

Question 2

Therapeutic effects of FQ’s ?

Answer 2

1. Urinary tract infection (UTI): FQs are effective against gram-negative bacilli, such as
   E. coli, Proteus and Enterobacter. They also have moderate activity against Pseudomonas infection. They are useful for the treatment of bacterial prostatitis as they are concentrated in the prostatic tissue.
   Bacterial diarrhoeas: FQs are effective for a variety of GI infections caused by E. coli, Shigella, Salmonella, etc. For traveller’s diarrhoea (due to E. coli), FQs are as effective as cotrimoxazole. Norfloxacin, ciprofloxacin or levofloxacin therapy for 3-5 days is adequate.
2. Respiratory infections: Newer FQs (levofloxacin and moxifloxacin - respiratory) are effective for community-acquired pneumonia and chronic bronchitis.
3. Typhoid fever: Azithromycin s the first-choice drug at present for treatment of typhoid fever (500 mg orally daily for 7 days). Ceftriaxone (2 g i.v. for 10 days) is preferred for par-enteral use. Alternative drugs are ciprofloxacin, cefipime, cotrimoxazole and chloramphen-icol. FQs are effective in eliminating chronic carrier state of Salmonella typhi when therapy is continued for 4 weeks as they attain effective concentration in bile and intestinal mucosa.
4. Mycobacterial infections: In multidrug-resistant TB (MDR-TB), atypical mycobacterial in-fections, MAC infection in AIDS patients and leprosy, FQs are used in combination with other AMAs.Moxifloxacin and levofloxacin are among the second-line antitubercular drugs.
5. Ciprofloxacin, levofloxacin, moxifloxacin and ofloxacin are used topically for conjunctivitis due to susceptible organisms.
6. Sexually transmitted diseases:
   G • Gonococcal infections: FQs were effective for the treatment of cervicitis and urethritis caused by N. gonorrhoeae but their use has declined because of high rates of resistance.
   • Chancroid: Ciprofloxacin in a dose of 500 mg bid. for 3 days is effective.
   • Chlamydial cervicitis and urethritis can be treated with levofloxacin or ofloxacin.
7. Skin, soft-tissue and bone infections due to S. aureus and gram-negative bacilli require prolonged antimicrobial therapy. FQs can be used in combination with an agent effective against anaerobes especially in diabetic foot infections.
8. Ciprofloxacin can be used to eradicate meningococci from nasopharynx, thus eliminating the carrier state, but the preferred drug is rifampin.
9. Prophylaxis and treatment of infections in neutropenic patients: FOs can be used.
10. Anthrax: Ciprofloxain is the preferred drug for treatment and prophylaxis of anthrax.

Question 3

Adverse effect of FQ’s

Answer 3

The common adverse effects are related to the GI tract, e.g. nausea, vomiting and abdominal discomfort.
• CNS effects include headache, dizziness, insomnia, confusion, hallucinations and convulsions.
• Hypersensitivity reactions include skin rashes, urticaria, itching, eosinophilia and photo-sensitivity.
• Tenosynovitis and tendon rupture can occur especially in athletes and elderly patients.

Question 4

MOA

Answer 4

MECHANISM OF ACTION
DNA gyrase (topoisomerase II) in gram-negative bacteria
Topoisomerase IV in gram-positive bacteria
Nicking, formation
of negative supercoils and resealing of strands of DNA
Nicking and separation of daughter
DNA strands following
DNA replication