Antimalarials Flashcards
describe plasmodiums pre-erythrocytic stage in its life cycle,
what is the infective form?
- sporozoite = infective form
- asymptomatic for up to 1 month
- invades and matures in hepatocytes → schizonts

describe plasmodiums erythrocytic stage in its life cycle
- schizonts rupture into merozoites
- merozoites go into blood stream → invade RBC’s where they form trophozoites
- trophozoites mature into schizonts
- schizonts digest hemoglobin and rupture into merozoites again → RBC lysis releases them

describe “cyclic fevers”
- “cyclic fevers” → plasmodium stages cycles occur every 2-3 days
- vivax/ovale: 48 hr cycles (fever on days 1 + 4)
- malaria/falciparum: 72 hr cycles
describe p. falciparum & p. malariae life cycle
- only 1 cycle of liver cell invasion
- liver infection stops in < 4 weeks
- only erythrocytic parasites have to be eliminated
describe p. vivax & p. ovale life cycle
- have a dormant hepatic stage
- erythrocytic and hepatic parasites have to be eliminated
describe malarial paroxysm
-
occurs every 2-3 days once infection is established
- fever
- anemia
- jaundice
- splenomegaly
- hepatomegaly
describe p. falciparum and its symptoms
- most severe disease (microvascular effects)
- fatal if untreated
- cerebral malaria (irritability → seizures → coma)
- symptoms
- respiratory distress syndrome
- diarrhea
- severe thrombocytopenia
- spont. abortion
- hypoglycemia
when treating malaria, treatment should be guided by:
-
type of plasmodium species infected
- falciparum: rapid illness/death
- vivax/ovale: treat hypnozoites dormant in liver
-
clinical status of the patient
- uncomplicated malaria: treat w/ oral antimalarials
- complicated malaria: treat aggressively with parenteral antimalarials
-
drug susceptibility of infecting parasite
- falciparum/vivax: different resistance patterns in different geographic areas
DOC for treatment, prophylaxis of p. vivax/ovale, and sensitive uncomplicated p. falciparum malaria
chloroquine
Chloroquine is highly effective against ____ parasites but not ____ parasites
Chloroquine is highly effective against blood parasites but not liver parasites
describe chloroquine’s MOA
- concentrates in parasite food vacuoles
- blocks heme polymerase → hemoglobin breakdown of heme cannot be made into non-toxic hemazoin

describe chloroquine PK and resistance
- oral, half life: 3-5 days → taken once weekly
- P. falciparum: mutations in putative transporter PfCRT
describe chloroquine AEs
- generally well tolerated
- pruritis (common in africans)
- nausea, vomiting, abdominal pain, headache, anorexia, malaise, blurring of vision, urticaria (uncommon)
- hemolysis (G6PD-deficient people)
- can cause electrocardiographic changes
Chloroquinine is contraindicated in patients with
- psoriasis or porphyria (may precipitate attacks)
- retinal or visual field abnormalities
is chloroquine safe to use in pregnancy or children?
yes!
what is 1st line therapy for severe falciparum disease?
quinine / quinidine
what is the difference between quinine and quinidine?
- quinine
- oral treatment of falciparum malaria
- quinidine
- parenteral treatment for severe falciparum malaria (D for death! = more severe!)
quinine/quinidine are rapidly-acting, highly effective against ___ parasites, but NOT active against ___ parasites
quinine/quinidine are rapidly-acting, highly effective against blood parasites, but NOT active against liver parasites
describe quinine/quinidine MOA
- Depresses O2 uptake and carbohydrate metabolism
- Intercalates into DNA, disrupting parasite replication and transcription
describe quinine/quinidine AEs
- Cinchonism: tinnitus, headache, nausea, dizziness, flushing & visual disturbances
- Hypersensitivity: skin rashes, urticaria, angioedema, bronchospasm
- Hematologic abnormalities: hemolysis (G6PD deficiency), leukopenia, agranulocytosis, thrombocytopenia
- Hypoglycemia: stimulation of insulin release
- Uterine contractions: still used in treatment of severe falciparum malaria in pregnancy
- Severe hypotension: too rapid IV infusion
- QT prolongation
- Blackwater fever: hemolysis & hemoglobinuria
quinine/quinidine contraindications
- Discontinue if signs of: severe cinchonis, hemolysis, hypersensitivity
- Avoid in pts with visual or auditory problems
- Use with caution in patients with:
- underlying cardiac abnormalities
- Can raise plasma levels of warfarin & digoxin
- Reduce dose in renal insufficiency
- Pregnancy category C however use in complicated malaria b/c benefits outweight risks
quinine/quinidine should NOT be used concurrently with
mefloquine
mefloquine is effective against _____ strains
mefloquine is effective against chloroquine-resistant strains
describe mefloquines MOA
destruction of the asexual blood forms of malarial pathogens
details unknown (thank god..)


