Parasitic%20infections Treatment

Drugs for Treatment of Amoebiasis

Luminal Amoebicides

• Eg Diloxanide furoate, Iodoquinol, Paromomycin
• These agents are effective in treating organisms in the bowel lumen
  
  • May be used in patients w/ asymptomatic E histolytica infection
• Recommended for asymptomatic cyst passers
  
  • To avoid the risk of developing invasive disease
  • To prevent secondary spread
• When asymptomatic cyst carriage persists after treatment for amoebic dysentery or liver abscess, further treatment w/ a luminal amoebicide is mandatory, otherwise relapse is frequent
• Paromomycin
  
  • Acts directly on amoeba w/ antibacterial activity against normal & pathogenic organisms in GI tract; binds to 30s ribosomal subunits interfering w/ bacterial protein synthesis
  • Temporarily eliminates diarrhea in human immunodeficiency virus (HIV) patients who have cryptosporidiosis
  • May also be used in treatment of cryptosporidiosis & giardiasis

Tissue Amoebicides

• Eg Chloroquine & Nitroimidazole derivatives (Metronidazole, Nimorazole, Ornidazole, Secnidazole & Tinidazole)
• These agents are effective in treating invasive amoebiasis but are less effective in treating organisms in the bowel lumen
• Chloroquine binds & inhibits DNA & RNA polymerase; it also raises parasite’s internal pH, restricting its growth
• Nitroimidazole derivatives cause damage to parasite DNA helical structure resulting in strand breakage & impaired template function

Other Antiprotozoan Drugs

• Eg Furazolidone, Nitazoxanide, Quinacrine

Furazolidone

• Used for the treatment of giardiasis
• Furazolidone is as effective as Metronidazole in the treatment of giardiasis
• Action: Causes damage to intracellular components

Nitazoxanide

• Action: Inhibits growth of sporozoites & oocysts of Cryptosporidium sp & trophozoites of G lamblia

Quinacrine (Mepacrine)

• Action: Suggested action is binding to parasite DNA thereby inhibiting RNA transcription & protein translation

Anthelminthic Drugs

Albendazole

• Has an exceptionally broad spectrum of antiparasitic activity
• Widely used for intestinal nematode infections
• Decreases ATP production in worms

Bithionol

• Preferred agent for F hepatica
• Release of worm antigens may cause reactions eg urticaria, photosensitivity reactions & GI symptoms

Ivermectin

• As effective as Thiabendazole against S stercoralis but has fewer untoward effects
• Action: Causes hyperpolarization of muscle & nerve cells of parasite leading to paralysis

Levamisole

• Action: Causes muscle paralysis in susceptible worms

Mebendazole

• Widely used for treatment of intestinal nematodes
• Poorly absorbed from the GI tract resulting in a low frequency of side effects
• Action: Blocks glucose & nutrient uptake irreversibly in susceptible worms

Metrifonate

• Alternative to Praziquantel in the treatment of S haematobium infection
• Action: Inhibits acetylcholinesterase

Niclosamide

• Action: Causes necrosis of head & segments of tapeworms

Oxamniquine

• Used only for S mansoni infection
• Action: Causes blood fluke to transfer from mesenteric veins to the liver where the males are retained; females return to mesentery but cannot release eggs anymore

Piperazine

• Action: Blocks acetylcholine effects at neuromuscular junction causing muscle paralysis

Praziquantel

• Highly effective against all Schistosoma sp that infect humans, adult & larval form of cestodes
  
  • Drug of choice for liver flukes
• Action: Increases cell permeability in helminths w/ loss of intracellular calcium & paralysis of musculature
• Drug resistance is a possibility, especially in countries practicing mass chemotherapy as a control measure

Pyrantel pamoate

• Used for the treatment of intestinal nematodes (roundworm, hookworm & pinworm)
• Action: Blocks acetylcholine effects at neuromuscular junction causing muscle paralysis

Thiabendazole

• Active against many intestinal adult nematodes & larval forms in tissues
• High frequency of untoward effects & the availability of alternative agents have limited its usefulness

Adequate Hydration & Nutrition

• Patients w/ parasitic infections frequently suffer from malabsorption, vomiting & diarrhea, resulting in malnutrition
• Ensure that patient’s nutritional & hydration status are maintained at acceptable levels

Replacement of Fluid & Electrolyte Losses

• Vomiting & diarrhea result in fluid & electrolyte losses, mainly Na & K

Blood Transfusion & Treatment w/ FeSO₄

• These measures may be necessary in hookworm infections which may cause severe anemia