Antiparasitic Chemotherapy Flashcards
Pharm. Chijioke (15 cards)
What are parasites? Classify them
A parasite is an organism that lives on or in a host organism and gets its food from or at the expense of its host.
Their three main classes are:
i. protozoa
ii. helminths
iii. ectoparasites.
Mention 5 Neglected Tropical Diseases (NTDs)
- Lymphatic filariasis
- Onchocerciasis (River blindness)
- Schistosomiasis
- Trypanosomiasis
- Leishmaniasis
- Dracunculiasis (Guinea-worm disease)
Mention two well-known ectoparasites and what they cause.
i. Lice - pediculosis
ii. Mites - scabies
Mention 5 ectoparasiticides.
- Sulphur
- Ivermectin
- Permethrin
- Lindane
- Benzyl benzoate
- Crotamiton
- Dicophane
Classify helminthes with examples.
i. Trematodes e.g. Fasciola hepatica (liver fluke), Schistosoma (blood fluke), Fasciolopsis buski (intestinal fluke), lung fluke
ii. Cestodes (tapeworms) e.g. Taenia solium (pork tapeworm), Taenia saginata (beeef tapeworm)
iii. Nematodes (roundworms) e.g. Ascaris lumbricoides, pin worm, hook worm, loa loa, whipworm
State the chometherapeutic agent for these infections
i. Trematode and cestode infections
ii. Nematode infections
iii. Amebiasis, giardiasis, and trichomoniasis.
i. Praziquantel
ii. Albendazole, mebendazole
iii. Metronidazole, tinidazole
What are the 11 classes of drugs used for antiprotozoal chemotherapy?
- Heavy metals
- Aminoquinoline analogues
- Phenanthrene-methanol
- Diamidines
- Nitroimidazoles
- Ornithine analogues
- Acetanilides
- Sulphated naphthylamines
- Folate antagonist
- Inhibitor of protein synthesis
- Oxidants
HAND SOAP FIO
Explain the mechanism of action of heavy metals with an example.
Arsenical derivative: Melarsoprol is a product of the reaction of arsenic oxide and 2,3-dimercaptopropanol.
They bind to the sulphydryl groups in enzymes and thus inhibit certain essential enzymatic activities.
Dimercaprol is a chelating agent used in the treatment of toxicity caused by most heavy metals.
As a component of melarsoprol, Dimercaprol is a chelating agent used to reduce the toxicity of arsenic oxide on the host.
Melarsoprol is the drug of choice for trypanosomiasis
Classify aminoquinoline analogues.
The agents in this group are available in 3 chemical sub-groups:
i. 4- aminoquinolines e.g chloroquine
ii. 8- aminoquinolines e.g primaquine
iii. Quinoline-methanols e.g Quinine and mefloquine
i and iii are active against the erythrocytic stage, while iii is active against the hepatic stage.
Discuss 4-aminoquinolines
Example: chloroquine
It accumulates in the food vacuoles of the plasmodium where it blocks the utilisation of the host haemoglobin as a source of needed amino acid.
It blocks the action heme plymerase leading to accumulation of toxic agent.
It is used for the erythrocytic forms of parasites, but not hepatic. They can also treat the extra-luminal and hepatic amoebiasis.
Discuss 8-aminoquinolines
Example: Primaquine
Its target of action is exo-erythrocytic stages of Plasmodium spp.
It produces radical cure of malaria.
Discuss Quinoline-methanols
Examples are: quinine and mefloquine
Members of this group include quinine and mefloquine
They are active against plasmodium especially P. falciparum and P. vivax
Their actions are limited to blood schizonts; they do not produce radical cure as hepatic forms of the parasite remain unaffected.
Quinine is useful in treating malaria caused by chloroquine-resistant P. falciparum
Mefloquine is used as prophylaxis and treatment of malaria caused by multi-drug resistant (particularly chloroquine –resistant) P. falciparum
Discuss Phenantherene-methanol
Example: Halofantrine
Active only against erythrocytic stage of plasmodium.
It is also useful against multidrug-resistant P. falciparum, including chloroquine-resistant strains.
Discuss Diamidines
Example: Pentamidine
-Second line drug (after co-trimoxazole) in the prevention and treatment of Pneumocystis carinni pneumonia in AIDS patients.
- Treatment of Leishmaniasis (L. aethiopica, L. guyanensis and L. brazilensis)
-Treatment of pre-cerebral forms of African trypanosomiasis.
- Doesnot penetrate the BBB, so it can’t be used in cerebral trypanosomiasis.
Discuss Nitroimidazoles
Examples: Metronidazole, Secnidazole, Tinidazole
- Treats both luminal and extra-luminal amoebiasis
- Metronidazole is the first-line drug for Trichosomiasis
- It is also used to treat giardiasis
- Metronidazole is also active against some anaerobic bacteria, such as Helicobacter sp., Clostridium and Bacteroides
