The anti-malarial drugs effective in preerythrocytic phase in liver are –
**Core Concept**
The preerythrocytic phase of malaria involves the liver stage where the parasite undergoes asexual reproduction within hepatocytes. Anti-malarial drugs effective during this phase must target the liver stage of the parasite.
**Why the Correct Answer is Right**
The correct answer involves drugs that target the liver stage of the malaria parasite, specifically Plasmodium species. These drugs work by inhibiting the development of the parasite within hepatocytes, thereby preventing further transmission. Tafenoquine, an 8-aminoquinoline, is a well-known anti-malarial drug that is effective in the preerythrocytic phase of the malaria parasite's life cycle. It works by targeting the parasite's hemozoin formation process and thereby inhibiting its growth within the liver.
**Why Each Wrong Option is Incorrect**
**Option A:** Chloroquine is effective against the erythrocytic stage of malaria, not the preerythrocytic stage. It works by inhibiting hemozoin formation, but its primary use is in treating malaria infections that have reached the blood stage.
**Option B:** Artemisinin is a fast-acting anti-malarial drug effective against the erythrocytic stage, not the preerythrocytic stage. It works by generating reactive oxygen species that damage the parasite, but it does not target the liver stage.
**Option C:** Primaquine is also an 8-aminoquinoline, but it is primarily used for its radical cure of malaria, targeting the dormant hypnozoites in the liver. While it does have some activity against the preerythrocytic stage, it is not the primary choice for targeting the liver stage.
**Clinical Pearl / High-Yield Fact**
Tafenoquine is a long-acting anti-malarial drug that can be used for prophylaxis in areas where malaria is endemic, as well as for treatment of malaria. It is particularly useful in areas where resistance to other anti-malarial drugs is a concern.
**Correct Answer: C. Tafenoquine**