antimalarials

Question 1

Chloroquine (ARALEN) and hydroxychloroquine (PLAQUENIL) MOA

Answer 1

“go-to drug”, for most sensitive forms
blood schizonticides, interferes with parasite’s feeding mechanisms, related to the drug’s ability to concentrate in and raise the pH of the parasite’s acidic food vacuoles
-clinical cure for all forms; radical cure for P. falciparum and P. malariae
-ppx if sensitive

Question 2

Chloroquine (ARALEN) and hydroxychloroquine (PLAQUENIL) toxicity/SEs

Answer 2

CNS - dizziness, headache, tinnitus
GI upset - should be taken with food
retinal and corneal toxicity - monitor visual function in patients.
immunologic - skin rashes; blood dyscrasias; lupus - like symptoms; contraindicated in patients with psoriosis and porphyria.

Question 3

Chloroquine (ARALEN) and hydroxychloroquine (PLAQUENIL)

Answer 3

Anti-inflammatory actions at high doses - Hydroxychloroquine (Plaquenil) is used in rheumatoid arthritis and lupus erythematosus.

Question 4

Quinine and *Quinidine Gluconate MOA

Answer 4

acts on erythrocytic forms, (schizonticidal), older, for chloroquine-resistant P. falciparum
gametocytocidal (P. vivax and P. malariae)
MOA similar to chloroquine
-resistant P. falciparum

Question 5

Quinine and *Quinidine Gluconate SEs

Answer 5

analgesia and antipyretic actions similar to aspirin
b. GI irritation, nausea, vomiting, etc..
c. blurred vision and auditory disturbances (tinnitus, deafness)
d. cardiovascular - quinidine-like depressant effect on heart
e. birth defects and abortion
f. skeletal muscle relaxation from mild neuromuscular blockade -used in low
doses for nocturnal leg cramps (e.g. Legatrim)
g. “Cinchonism” - syndrome of quinine toxicity that resembles salicylism
(headache, nausea, dizziness, blurred vision, tinnitus).

Question 6

Mefloquine (LARIAM)

Answer 6

Acts on erythrocytic forms of the parasite (schizonticidal) like chloraquine
-for chloroquine-resistant and multidrug resistant
strains of P. falciparum

Question 7

Mefloquine (LARIAM) SEs

Answer 7

can cause seizures and may aggrevate latent psychoses. It should not be used in patients with a history of mental illness or epilepsy.
Because of potential cardiac and CNS toxicities, the drug should be used with extreme caution in patients with CV disorders, psyciatric problems, or epilepsy

Question 8

pyrimethamine (DARAPRIM) and proguanil (AKA chloroguanide) (PALUDRINE)

Answer 8

inhibits parasites’ dihydrofolate reductase, main effect is on erythrocytic forms.
sporozoite and pre-erythrocytic stages, and cryptomerozoites (secondary tissue forms).

Question 9

pyrimethamine (DARAPRIM) and proguanil (AKA chloroguanide) (PALUDRINE) use

Answer 9

ppx, particularly for chloroquine resistant strains of P. falciparum

• combo w. sulfa: pyimethamine plus sulfadoxine (Fansidar) for presumptive tx
• lso used on conjunction with artemisinin analogs for treatment of chloroquine-resistant P. falciparum

Question 10

Atovaquone + proguanil (Malarone)

Answer 10

newer

• acts by depolarizing the parasite’s mitochondria and inhibiting electron transport
• alternative to mefloquine or doxycycline for prophylaxis against chloroquine-resistant P. falciparium. It is fairly expensive and must be taken daily.

Question 11

Primaquine

Answer 11

• tissue forms* (exoerythrocytic) of all species of plasmodia
• gametocytocidal
• little effect on erythrocytic forms
• not good ppx bc of fox
• tried in combo w. clindamycin for PJP tx

Question 12

Primaquine SEs

Answer 12

hemolytic anemia (esp. G6PD def. -may confer resistance to malaria)
teratogen
GI
CNS

Question 13

doxycycline (and other tetracyclines)

Answer 13

antimalarial activity and are used as alternate or adjunctive drugs for the treatment and prophylaxis of malaria.

Question 14

focus on the chart

Answer 14

at the end

Question 15

P. falciparum

Answer 15

fever recurs every third day; no secondary tissue forms; drug resistant forms are becoming a serious problem.
-may be mixed infection w. P. vivax

Question 16

P. vivax -

Answer 16

benign tertian malaria, most common form; fever every third day; secondary tissue forms; relapses; resistant strains are becoming more widespread.
P. ovale v. similar
-can be asymptomatic for months

Question 17

P. malariae

Answer 17

quartan malaria; fairly rare; fever every fourth day; no secondary tissue forms.

Question 18

life cycle

Answer 18

sporozoites from anopheles mosquito saliva–>enter the hepatic parenchymal cells (exoerythrocytic stage)–>ndergo asexual replication to be liberated as merozoites–>invade RBCs (erythrocytic stage) where they enlarge and multiply to form schizonts (schizogony)–>RBCs lyse–>releasing merozoites along with various metabolites and toxins which are responsible for the fever and chills–>free merozoites can infect more RBCs or differentiate into gametocyte (sexual forms)–>may be ingested by another mosquito where development into sporozoites continues, thus completing the cycle

Question 19

Blood schizonticides vs Tissue schizonticides

Answer 19

blood: suppress symptoms and provide a so called “clinical cure”, do not affect the secondary tissue forms of P. vivax and P. ovale
tissue: act on hepatic stages of the parasite, target P. vivax and P. ovale

Gametocytocidal agents - act on gametocytes; helps reduce spread

Question 20

w. P. vivax and P. ovale, some of the hepatic forms of the parasite can become dormant for ??

Answer 20

months -years (secondary tissue forms or “crypozoites”). This is why individuals who are infected with P. vivax or P. ovale can suffer relapses

Question 21

Causal prophylaxis

Answer 21

not practical; too many toxic effects, act on hepatic form

-primaquine, pyrimethamine and proguanil

Question 22

Suppressive Agents

Answer 22

act on erythrocytic forms to suppress symptoms

chloroquine

Question 23

artemether/lumefantrine (Coartem)

Answer 23

all forms including chloroquine-
resistant P. falciparum
-rapidly becoming primary drug of choice
-can be given IM
-used in combo

Question 24

artemisinin

Answer 24

blood schizonticide