Antiprotozoal Drugs
Antiprotozoal drugs are used to treat infections caused by protozoa—single-celled parasites responsible for diseases like malaria, amebiasis, and leishmaniasis.
Classification
- 1. Amebiasis: Chloroquine, Metronidazole, Tinidazole
- 2. Malaria: Mefloquine, Quinidine
- 3. Trypanosomiasis: Benznidazole, Suramin
- 4. Leishmaniasis: Miltefosine
- 5. Giardiasis: Nitazoxanide
Pharmacodynamics
- Chloroquine, Metronidazole, Tinidazole (Amebiasis): Disrupt protozoal DNA synthesis → cell death
- Mefloquine, Quinidine (Malaria): Inhibit heme polymerase → accumulation of toxic heme → parasite death
- Benznidazole, Suramin (Trypanosomiasis): Generate reactive oxygen species / inhibit energy metabolism
- Miltefosine (Leishmaniasis): Disrupts cell membrane integrity → induces protozoal apoptosis
- Nitazoxanide (Giardiasis): Inhibits pyruvate-ferredoxin oxidoreductase → energy metabolism failure
Side Effects
- Common: Nausea, vomiting, diarrhea, headache, dizziness
- Serious/Rare:
- Allergic reactions – e.g. Stevens-Johnson syndrome
- Hepatotoxicity
- Neurotoxicity – especially with quinidine
- Hematologic – anemia, leukopenia
Drug Interactions
- Metronidazole: Potentiates warfarin → ↑ bleeding risk
- Tinidazole: Causes disulfiram-like reaction with alcohol
- Nitazoxanide: ↑ levels of highly protein-bound drugs
- Suramin: Nephrotoxicity ↑ with other nephrotoxic agents
- Quinidine: Inhibits digoxin metabolism → ↑ digoxin toxicity