Antiparasitic drugs treat infections caused by parasites like helminths, ectoparasites, and protozoa. They work by killing the parasite or inhibiting its growth. Ideal antiparasitic drugs have a wide spectrum of activity, are effective orally and in single doses, and leave minimal residues. Common classes of antiparasitic drugs include nitroimidazoles, which treat protozoal infections, and anthelmintics which treat helminth infections. Specific drugs are used to treat different parasite types, like benzimidazoles for nematodes, niclosamide for cestodes, and praziquantel for trematodes.

1. ANTIPARASITICIDES
Presented by,
S.ATSHAYA

2. DEFINITION:
• Antiparasitics are class of medications which are indicated for the treatment of
parasitic diseases, such as those caused by helminths, ectoparasites, and protozoa.
• Antiparasitics target the parasitic agents of the Infections by destroying them or
inhibiting their growth , they are usually effective against a limited number of
parasites within a particular class.
• They are two major groups of parasites : Multicellular helminths(worms) and single –
celled protozoa .

3. IDEAL ANTI-PARASITIC DRUG:
• A wide therapeutic index
• Broad spectrum of activity
• Effective orally
• Effective in a single dose
• Leave no or low tissue residues
• Economical
• Inhibit re-infection for extended periods.

4. ANTIPROTOZOAL DRUGS:
• Antiprotozoal drug is any agent that
kills or inhibit the growth of
protozoans.

5. NITROIMIDAZOLES:
• Metronidazole is usually given orally for the treatment of protozoal infections and it
is effective in treating bacterial infections caused by anaerobes.
• Nitroimidazoles are active on protozoa whose energy metabolism is anaerobic.
Uses:
• Metronidazole can be combined with nitrofurazone and methylene blue as an
alternative treatment for anchors worms ,especially for trichlorfon sensitive fish
• Dosage: 250-500mg per 20 gallons . treat every 48 hours (24 hours for severe
problems ) with a 25% water change before treatment . treat for 10 days.

6. ANTHELMINTIC DRUG:
• Pathogenic helminths can be divided into the following major group:
• Cestodes (flatworms)
• Nematodes(round-worm)
• Trematodes(flukes)
• Acanthocephala (thorny-headed worms)
• Most available anthelmintic drugs exert their antiparasitic effects by interference with,
• Energy metabolism.
• Neuromuscular coordination.
• Microtubular function .
• Cellular permeability.

7. TREATMENT FOR INFECTIONS CAUSED BY NEMATODES:
• Benzimidazoles :mainly mebendazole ,thiabendazole and albendazole, they have a
broad range of activity against many nematode and cestode parasites.
• Piperazine : it works by causing a paralysis within the muscles lining the body wall
of these worms .
• Uses : piperazine is proven effective for capillaria nematode worms that infest the
intestines of angelfish .

9. CONT.…,
• Ivermectin : the does not cross the blood brain barrier and therefore has no paralytic
action in mammals ,but in fishes they causes hyperpolarization of the parasite cell
membrane and muscle paralysis .
• It is administered by the oral and subcutaneous routes, it is rapidly absorbed .
• Half life is approximately 12 hours.

10. LEVAMISOLE:
• Antiparasitic agent ,can stimulate formation of antibodies to various antigen
,enhance T-cell activation and proliferation ,potentiate monocyte and macrophage
functions including phagocytosis and chemotaxis.
• Dosage : if levamisole cannot be located ,the use of levamisole HCL found in
commercial usage.
• Levamisole HCL will treat 10 gallons (38lit) with a required 2ppm concentration.

11. TREATMENT FOR INFECTIONS CAUSED BY CESTODES:
• Niclosamide : for many years niclosamide which is a chlorinated salicylamide ,this
drug affects the scolex and proximal segments of the cestodes ,resulting in the
detachment of scolex from the intestinal wall and eventual evacuation of the
cestodes from the intestine by the normal peristaltic action of the hosts bowel.
• They are extensively used in the treatment of tapeworm infections caused by
Diphyllobothrium latum.

12. TREATMENT OF INFECTIONS CAUSED BY TREMATODES:
• Praziquantel: they increase the parasite motility which leads to spastic paralysis.
• It is am broad –spectrum anthelminthic
• It is most effective of the drugs used in the treatment of schistosomiasis

14. CONTRAINDICATORS:
• They include malachite green , crystal violet and brilliant green are in the
triarylmethane dye class of dyes.
• MG is considered to be the most effective antifungal treatment in aquaculture ,but
also used to control external protozoan Ichthyophthirius multifilis in fish .
• Oodinium pilularis – also known as velvet , this is actually caused by a parasite

15. METHYLENE BLUE:
• A heterocyclic aromatic chemical compound .
• The therapeutic action of methylene blue on bacteria and other parasites is
probably due to its binding effect with cytoplasmic structures within the cell and
also its interference with oxidation- reduction processes.
• They can be used for crustaceans ,including crabs, shrimp, and snails,but must be
introduced carefully.

16. CONT …,
• Xanthene dyes consist of compounds such as fluorescein, rhodamine, and eosin.
• These dyes were added to pesticide formulations used in sea lice treatment
• Others drugs :
• Acridines.
• Acriflavine.
• Azo dyes.

17. COMMON DISINFECTANTS USED FOR
PROTOZOAN DISEASES:
• Ich disease- formalin 250mg /l and potassium permanganate 2mg /l
• Costiasis –potassium permanganate immersion
• Whirling disease-1% of sodium hydroxide and potassium hydroxide.
• Trichodina- potassium permanganate and formaldehyde bath
• Velvet disease – copper @0.2mg /l , acriflavine @0.2%