Basic principles of antifungal, antiparasitic, and antiviral therapy.

Antifungal agents

Cell wall-targeting agnets, cell membrane synthesis inhibitors, cell division inhibitors, DNA synthesis inhibitors

Eg:- Polyenes, Azoles

Mechanism of antifungal agents

a) Echinocandins → inhibitors of cell wall synthesis
b) New group – Sordarins → inhibition of protein assembly
c) Azoles, polyenes, and terbinafine → damage the fungal cell membrane
d) Flucytosine → disruption and inhibition of DNA synthesis; converted into 5-fluorouracil metabolite that blocks fungal DNA/RNA synthesis

Antiviral

•  Agents must block specific stages of the viral life cycle (entry, uncoating, replication, release).

• Target: nucleic acid synthesis and maturation

Antiviral agents according to their target:

• Adsorption inhibitors
• Virus-cell fusion inhibitors
• Decapsidation inhibitors
• Nucleic acid synthesis inhibitors
• Transcription inhibitors
• Translation inhibitors
• Virus maturation inhibitors
• Virus release inhibitors

Antiviral Substances

DNA viruses: Cidofovir, Brivudin

RNA viruses: Pleconaril, Ribavirin

Mechanism of Action of Antiprotozoal Agents

• Damage to cell wall or membrane (Albendazol)

• Inhibition of nucleic acid synthesis (Chloroquine)

Classification of anthelmintic agents

1. Agents affecting the microtubule system → Benzimidazoles

2. Agents affecting the nervous system
• Agents acting on excitatory (cholinergic) synapses
• Agents acting on inhibitory synapses

3. Agents affecting energy metabolism

4. Other agents

Eg:- Benzimidazoles, Thiazolides