Quinolone's and anti-viral agents

Question 1

Classification of Quinolone’s?

Answer 1

1st gen: Nalidixic acid (narrow spectrum of activity, most effective against Gram - organisms

2nd gen: “Ciprofloxacin” has a broader spectrum of action compared to gen 1, improved intracellular penetration.

3rd gen: “Levofloxacin” maintain the spectrum of activity from the second generation, but have an enhanced activity against streptococcus species.

4th gen: “Moxifloxacin” have enhanced gram positive activity.

Question 2

Pharmacology of the Quinolone’s

Answer 2

Quinolones target the DNA gyrase in gram negative and topoisomerase 4 in the gram positive bacteria for the overall effect of rapid cell death (disturbances in DNA ligation).

Resistance against these agents is by 3 main mechanisms:

1. Increased degeneration (Aminoglycoside acetyl transferase acetylates the quinolone into an inactive drug form).
2. Decreased accumulation (Efflux pumps and reduced cellular permeability).
3. Altered target binding (mutations in the genes encoding for the bacterial DNA gyrase and topoisomerase 4).

Quinolones have a good oral absorption, which can be disturbed by co-administration of “iron” and “zinc”. They have a wide distribution and penetration into the CNS, so they can be employed for the treatment of CNS infection. Key areas in which quinolones accumulate are the kidneys, bones, and prostate. Quinolones are excreted via glomerular filtration.

Adverse effects - Tendonitis, tendon rupture, peripheral neuropathy and numerous CNS effects ( hallucinations, anxiety, insomnia and confusion etc).

Question 3

Classification of the anti-viral drugs?

Answer 3

1. Drugs for herpes virus and CMV infection
2. Anti-retroviral agents
3. Anti-influenza agents
4. Drugs for hepatic viral infections