Antimalarial Drugs

Question 1

What is malaria and the phases of it’s lifecycle?

Answer 1

Malaria is a parasitic disease caused by plasmodium which is carried by the female anopheles mosquito.

It has two phases: Asexual phase and Sexual phase

Question 2

Describe the features of the asexual phase?

Answer 2

This phase occurs in the human body, when the sporozoites is injected into the liver cells is known as the (pre- erythrocytic phase). In the liver the sporozoites develops to form merozoite which later ruptures and are released into the RBCs and becomes trophozoites (Erythrocytic phase).
Some of the shizont remain in the liver as hypnozoites (Exo-erythrocytic phase) and this usually occurs in plasmodium vivax and ovale. It responsible for relapse of malaria after treatment. The RBCs ruptures and releases merozoites which develops into gametocyte the sexual form of the parasite which the mosquito picks up .

Question 3

Describe the sexual phase?

Answer 3

It occurs in the mosquito.

Question 4

Classifications of antimalarial drugs?

4

Answer 4

Drugs that are used to treat acute attack
Drugs that effect a radical cure
Drugs used for chemoprophylaxis
Drugs used to prevent transmission

Question 5

Drugs that are used for acute attack?

Answer 5

These drugs are also called blood shizonticidial drugs . They act on the erythrocytic form of the plasmodium. This group of drugs include: artemesine and related compounds. These drugs are usually combined with other drugs e.g arthesumate, arthether,etc.

Question 6

Quinolones

E.g quinine, mefloquine, chloroquine, amodiaquine.

Answer 6

Side effects of quinine
Bitter taste, GIT disturbance

Note: If it is used in large doses it can cause arrhythmia.

Question 7

What are the side effects of chloroquine?

Answer 7

GIT disturbances, Arrhythmia occurs if administered in large doses.

Note: Chloroquine is considered safe for pregnant women.

Question 8

Side effects of mefloquine?

Answer 8

GIT disturbances

Note: It is contraindicated in pregnancy because of it’s teratogenic potential.

Question 9

Drugs that effect a radical cure ?

Primaquine

Answer 9

This drugs are also called tissue schizonticidial drugs, they eradicate plasmodium vivax and ovale in the liver. They act to destroy the gametocyte and thus reducing the spread of infection.

Side effects
GIT disturbances, Methemoglobinemia

Question 10

Drugs used for chemoprophylaxis?

Drugs used for this purpose are mainly arthemicillin derivatives; Chloroquine, Lumefrantine, Doxicycllin, Pyrimethamine.

Answer 10

These drugs are also known as causal prophylaxis drugs. They block the link between the Exo-erythrocytic stage and erythrocytic stage thus preventing malaria.

They are often used in combinations. E.g Lumefantrine + Arthemether = Quatem

Question 11

Drugs used to prevent transmission

Answer 11

Primaquine, Proguanine, Pyrimethanine.

They can destroy gametocyte preventing transmission by mosquitoes.