21-09-2013, 12:52 PM
ANTIMALARIAL AGENTS
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MALARIA
Malaria is cause by four species of protozoa:
Plasmodium malariae.
P. falciparum.
P. vivax.
P. ovale (rare).
The plasmodium transmitted to human by the bite of an infected female anopheles mosquito
PLASMODIUM LIFE CYCLE
Asexual cycle: occurs in the human has two phases
Exoerythrocytic phase
Occurs “outside” the erythrocyte
Also known as the tissue phase
Erythrocytic phase
Occurs “inside” the erythrocyte
Also known as the blood phase
Classification of Anti-malarial Drugs
According to site of action
1.Tissue Hepatic Schizonticides /Acting on Hepatic cycle/
a. Drug effective against primary tissue forms-- Pre-erythrocytic stage / for Causal prophylaxis
. Proguanil
b. Drug effective against developing or dormant tissue forms/ for Terminal prophylaxis or Radical cure
. Primaquine
Chemical Classification
1. Cinchona Alkaloids: Quinine
2. 4-Aminoquinolines: Chloroquine, Amodiaquine
3. Bisquinoline: Piperaquine
8-Aminoquinolines: Primaquine
4. Quinoline Methanols: Mefloquine , Quinidine
5. Folate antagonists: Proguanil, Pyrimethamine
6. Sulfonamides: Sulfadoxine
7. Sulphone: Dapsone
8. Antibiotics: Doxycycline, Clindamycin
9. Miscellaneous : Halofantrine & Lumefantrine, Atovaquone, Artemisinin
Primaquine
It is a tissue schizonticide.
It is a 8- aminoquinoline derivative
MOA:
It forms radical atoms at 8-amino group by autooxidation which generates ROS, leading to destruction of mitochondria.
Gametocide, so inhibits infection transmission by mosquito.
Uses:
Eradication of liver stages (hypnozoites) of P.vivax & P.
ovale, after standard chloroquine therapy to prevent relapse.
It should not be given if there is risk of reinfection.