Antiprotozoal: Mixed Amebicide (luminal and systemic activity)

DOC for E. histolytic, G. lamblia, T. vaginalis: aka amebiasis (metronidazole + luminal amebicid); Giardiasis or Trichomoniasis (Single metronidazole treatment; If disease progresses to liver stage and is symptomatic, must have combo metronidazole + luminal amoebacide; if non-symptomatic liver stage, only luminal amoebicide

Mechanism: prodrug, non-enzymatically reduced by reaciting with reduced ferredoxin (only found in aerobes), metronidazole metabolites are taken up into DNA And form unstable molecules

Tox: disulfram effect (no EtOH)

Other Drugs: Tinidazole (Tindimax) - if can't respond to metronidazole

Antiprotozoal: Luminal amebicide

Use: E. histolyica, often combo with Metronidazole; Asymptomatic amebiasis

Unknown Mechanism:

Tox: Skin rxns, headache, thyroid enlargement (high Iodine content); serious adverse effects of the eye (optic neuritis, optic atrophy) leading to blindness

 Other Drugs: Diloxanide Furoate (Furamide) - luminal trophozoite effect

Luminal Amebocide: Aminoglycoside

Use: Luminal trophozoites (amebicide); effective against asymptomatic amebiasis, giardiasis, T vaginalis

PHK: not significantly absorbed in GI tract (no ototox or nephrotox)

Side effects: GI upset mainly

Antiprotozoal

Use: Tx of choice for toxoplasmosis; administer with folinic acid (leucovorin (wellcovorin))

Other Drugs: Emetine and Dehydroemetine (Mebadin) - alternatives to  metronidazole

Use: DOC pneumocystis jirovecii (BOARD) PCP pneumonia; toxoplasmosis; Pneumocystis prophylaxis

Mechanism: inhibition of folate metabolism

Side effects: 30% of AIDS pts can't tolerate the drugs; rash, pruritis, cytopenias and AST/ALT elevations

Use: Alternative to Trimethoprim plus Sulfamethoxazole (Bactrim) DOC pneumocystosis; treats active infection

Side effects: renal dysfunction, hypotension, arrhythmias, hypoglycemia

Antihelmintic

Use: Rounworm (nematodes), pinworms, hookworms: broad spectrum 

Mechanism: Cholinesterase inhibitor; produces depolarizing neuromuscular blockade in the worm (paralyzes the worm). Worm NMJ more sensitive than human

PHK: little is absorbed, only works in GI

Other Drugs: Ivermectin (Mectizan) - paralyzes the parasite, intensifies GABA transmission in peripheral nerves of worm

Antihelmintic: only at CDC

DOC: all schistosome; effective against many cestodes (tapeworms) and trematodes (flukes)

Mechanism: increase worm's permeability to Ca2+, leads to contraction and paralysis of worm's muscles

Other Drugs: Bithionol (Bitin) - liver and lung fluke

Paralyses worm and you pass it

Mostly filarial roundworms