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Pharm > Antimalarials > Flashcards

Antimalarials Flashcards

1
Q

describe plasmodiums pre-erythrocytic stage in its life cycle,

what is the infective form?

A
  • sporozoite = infective form
  • asymptomatic for up to 1 month
  • invades and matures in hepatocytes → schizonts
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2
Q

describe plasmodiums erythrocytic stage in its life cycle

A
  • ​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
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3
Q

describe “cyclic fevers”

A
  • “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
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4
Q

describe p. falciparum & p. malariae life cycle

A
  • only 1 cycle of liver cell invasion
  • liver infection stops in < 4 weeks
  • only erythrocytic parasites have to be eliminated
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5
Q

describe p. vivax & p. ovale life cycle

A
  • have a dormant hepatic stage
  • erythrocytic and hepatic parasites have to be eliminated
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6
Q

describe malarial paroxysm

A
  • occurs every 2-3 days once infection is established
    • ​fever
    • anemia
    • jaundice
    • splenomegaly
    • hepatomegaly
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7
Q

describe p. falciparum and its symptoms

A
  • most severe disease (microvascular effects)
  • fatal if untreated
  • cerebral malaria (irritability → seizures → coma)
  • symptoms
    • respiratory distress syndrome
    • diarrhea
    • severe thrombocytopenia
    • spont. abortion
    • hypoglycemia
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8
Q

when treating malaria, treatment should be guided by:

A
  1. type of plasmodium species infected
    • falciparum: rapid illness/death
    • vivax/ovale: treat hypnozoites dormant in liver
  2. clinical status of the patient
    • uncomplicated malaria: treat w/ oral antimalarials
    • complicated malaria: treat aggressively with parenteral antimalarials
  3. drug susceptibility of infecting parasite
    • falciparum/vivax: different resistance patterns in different geographic areas
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9
Q

DOC for treatment, prophylaxis of p. vivax/ovale, and sensitive uncomplicated p. falciparum malaria

A

chloroquine

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10
Q

Chloroquine is highly effective against ____ parasites but not ____ parasites

A

Chloroquine is highly effective against blood parasites but not liver parasites

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11
Q

describe chloroquine’s MOA

A
  • concentrates in parasite food vacuoles
  • blocks heme polymerase → hemoglobin breakdown of heme cannot be made into non-toxic hemazoin
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12
Q

describe chloroquine PK and resistance

A
  • oral, half life: 3-5 days → taken once weekly
  • P. falciparum: mutations in putative transporter PfCRT
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13
Q

describe chloroquine AEs

A
  • 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
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14
Q

Chloroquinine is contraindicated in patients with

A
  • psoriasis or porphyria (may precipitate attacks)
  • retinal or visual field abnormalities
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15
Q

is chloroquine safe to use in pregnancy or children?

A

yes!

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16
Q

what is 1st line therapy for severe falciparum disease?

A

quinine / quinidine

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17
Q

what is the difference between quinine and quinidine?

A
  • quinine
    • oral treatment of falciparum malaria
  • quinidine
    • parenteral treatment for severe falciparum malaria (D for death! = more severe!)
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18
Q

quinine/quinidine are rapidly-acting, highly effective against ___ parasites, but NOT active against ___ parasites

A

quinine/quinidine are rapidly-acting, highly effective against blood parasites, but NOT active against liver parasites

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19
Q

describe quinine/quinidine MOA

A
  • Depresses O2 uptake and carbohydrate metabolism
  • Intercalates into DNA, disrupting parasite replication and transcription
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20
Q

describe quinine/quinidine AEs

A
  • 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
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21
Q

quinine/quinidine contraindications

A
  • 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
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22
Q

quinine/quinidine should NOT be used concurrently with

A

mefloquine

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23
Q

mefloquine is effective against _____ strains

A

mefloquine is effective against chloroquine-resistant strains

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24
Q

describe mefloquines MOA

A

destruction of the asexual blood forms of malarial pathogens

details unknown (thank god..)

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25
Q

___ is the only medication recommended for chemoprophylaxis in pregnant women in chloroquine-resistant areas

A

mefloquine is the only medication recommended for chemoprophylaxis in pregnant women in chloroquine-resistant areas

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26
Q

___ and ____ are used in treatment of uncomplicated malaria in regions of Southeast Asia

A

mefloquine and artesunate are used in treatment of uncomplicated malaria in regions of Southeast Asia

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27
Q

describe mefloquine pharmokinetics

A
  • oral only
  • t1/2 = 20 days
    • weekly prophylactic dosing
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28
Q

describe mefloquine AEs

A
  • serious neurological and psychiatric toxicities:
    • dizziness, loss of balance
    • ringing in the ears
    • anxiety, depression
    • hallucinations
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29
Q

contrast mefloquine AEs with weak vs high dosing

A
  • weak dose
    • nausea, vomiting, diarrhea
    • dizziness
    • sleep and behavioral disturbances
    • rash
  • high dose
    • leukocytosis
    • thrombocytopenia
    • aminotransferase elevations
    • arrhythmias
    • bradycardia
30
Q

mefloquine is contraindicated in patients with history of

A
  • epilepsy
  • psychiatric disorders
  • arrhythmia, cardiac conduction defects
  • sensitivity to related drugs
31
Q

mefloquine should NOT be coadministered with

A

quinine/quinidine

halofantrine

32
Q

DOC for eradication of dormant liver forms of p. vivax and p. ovale?

A

Primaquine

33
Q

describe the clincal applications for Primaquine

A
  • therapy of acute vivax and ovale malaria
  • terminal prophylaxis of vivax and ovale malaria
  • chemoprophylaxis: protection against falciparum & vivax (toxicities are a concern – reserved for when other drugs cannot be used)
34
Q

describe primoquines AE

A
  • Hemolysis or methemoglobinemia (especially in G6PD deficient patients
    • primaquine oxidizes GSH to GSSG → less GSH available to neutralize toxic compounds
35
Q

patients should be tested for ____ before prescribing primaquine

withhold treatment if severely deficient

A

patients should be tested for G6PD deficiency before prescribing primaquine

withhold treatment if severely deficient

36
Q

can you give primaquine to pregnant women?

A

NO!

37
Q

Malarone = ____ + ____

clinal application?

A

atovaquone + proguanil

treatment & prophylaxis for p. falciparum

38
Q

malarone is active against _____ and ____ schizonts

A

malarone is active against tissue and erythrocytic schizonts

39
Q

___ should be used 1-2 days before travel and discontinued 1 week after exposure

A

Malarone should be used 1-2 days before travel and discontinued 1 week after exposure

40
Q

Malarone disrupts ____ and is taken ___

A

Malarone disrupts mitochondrial electron transport and is taken orally

41
Q

can you use malarone during pregnancy?

A

NOPE!

42
Q

list inhibitors of folate synthesis

A
  • pyrimethamine
  • proguanil
  • sulfadoxine
43
Q

describe the clincal application of folate synthesis inhibitors

A
  • Intermittent Preventive Therapy: high-risk patients receive intermittent therapy regardless of infection status
  • treatment of chloroquine-resistant falciparum malaria: pyrimethamine-sulfadoxine commonly used
    DO NOT use for severe malaria
44
Q

Pyrimethamine + Proguanil act slowly against ____ forms of all malaria species

A

Pyrimethamine + Proguanil act slowly against erythrocytic forms of all malaria species

45
Q

____ (a folate synthesis inhibitor) has some activity against hepatic forms

A

proguanil (a folate synthesis inhibitor) has some activity against hepatic forms

46
Q

___, a folate synthesis inhibitor, are weakly active against erythrocytic schizonts

A

sulfonamides, a folate synthesis inhibitor, are weakly active against erythrocytic schizonts

47
Q

which folate synthesis inhibitors act where?

A
48
Q

Proguanil AEs

A
  • mouth ulcers
  • alopecia = rare
49
Q

Pyrimethamine-Sulfadoxine AEs

A
  • erythema multiforme
  • Steven-Johnson syndrome
  • toxic epidermal necrolysis
50
Q

Sulfadoxine AEs

A
  • hematologic
  • GI, CNS, dermatologic & renal toxicity
51
Q

which FSIs are safe/unsafe in pregnancy?

A
  • Safe:
    • proguanil
    • pyrimethamine-sulfadoxine
  • Not safe:
    • sulfonamides
52
Q

Doxycyline is active against ___ schizonts of all malaria parasites but not against ____ stage

A

Doxycyline is active against erythrocytic schizonts of all malaria parasites but not against liver stage

53
Q

_____ is used to complete treatment for severe falciparum malaria (given along with quinine) after initial treatment with quinine, quinidine or artesunate.

It is also a ___ against most forms: must be taken daily

A

Doxycylcine is used to complete treatment for severe falciparum malaria (given along with quinine) after initial treatment with quinine/quinidine or artesunate.

It is also a chemoprophylaxis against most forms: must be taken daily

54
Q

Doxycylcine AEs

A
  • GI, candidal vaginitis, photosensitivity
  • discoloration & hypoplasia of teeth, stunting of growth
  • Fatal hepatotoxicity (in pregnancy)
55
Q

Doxycycline contraindications

A

pregnancy or children < 8y (FDA Category D)

56
Q

Artemisinin variations

A
  • Artesunate, Artemether, Dihydroartemisinin
  • Coartem: artemether + lumefantrine
57
Q

____ is used for treating severe falciparum malaria (IV). It has no ___ stage effect and should not be used as single agent to protect against resistance.

A

Artemisinin is used for treating severe falciparum malaria (IV). It has no liver stage effect and should not be used as single agent to protect against resistance.

58
Q

Artemisinin binds to ____ → breaks down peroxide bridges → produces ___ → damages parasite proteins

It has a ___ half life

A

Artemisinin binds to iron → breaks down peroxide bridges → produces free radicals → damages parasite proteins

It has a very short half life

59
Q

Artemisinin AEs

A
  • overall remarkably safe (nausea, vomiting, diarrhea)
  • very high doses: neurotoxicity, QT prolongation
  • more evidence for use in 2nd and 3rd trimesters of pregnancy
  • CAN be used for treatment of severe malaria in 1st trimester
60
Q

___ can be used as an alternative to doxycycline

A

Clindamycin can be used as an alternative to doxycycline

61
Q

Halofantrine is effective against ____ stages of all parasites

Use is limited by irregular absorption, cardiac toxicity, and is _____

A

Halofantrine is effective against erythrocytic stages of all parasites

Use is limited by irregular absorption, cardiac toxicity, and is Teratogenic

62
Q

describe lumefantrine

A
  • Effective against erythrocytic stages of all parasites
  • Available only as fixed-dose combination with artemether
  • Causes minor QT prolongation (clinically insignificant)
  • Well tolerated
63
Q

Safe vs unsafe drugs in pregnancy

A
  • Safe: Mefloquine, Proguanil, Chloroquine, Primethamine-Sulfadoxe, Artemisins
  • Unsafe/Contraindicated: Malarone, Primalquine, Sulfonamides
64
Q

Recommended drug(s) for

  • P. malariae (all regions, no resistance)

- P. falciparum with no resistance

A

chloroquine

65
Q

Recommended drug(s) for P. falciparum with chloroquine-resistance?

A
  1. Atovaquone-proguanil (Malarone)
  2. Artemether-lumefantrine (coartem)
  3. Quinine + Doxycycline
  4. Mefloquine
66
Q

Recommended drug(s) for p. vivax/ovale (no resistance, all regions)

A

Chloroquine/Hydroxychloroquine + Primaquine

Why??
Primaquine = one of few drugs acting in hepatic stage

67
Q

Recommended drug(s) for P. vivax with chloroquine-resistance

A
  1. Quinine + Doxycycline + primaquine
  2. Atovaquone-Proguanil + primaquine
  3. Mefloquine + primaquine
68
Q

treating severe malaria of all species, all regions

A

IV: Quinidine & Doxycycline or Clindamycin

or

IV: Artesunate followed by Atovaquone-Proguanil, Clindamycin, or Mefloquine

(can progress to oral quinine + doxycycline)

69
Q

treating uncomplicated malaria in pregnancy

A

Chloroquine-sensitive:
chloroquine/hydrochloroquine

  • *Chloroquine-resistant p. falciparum:**
    1. Mefloquine
    2. Quinine+clindamycin

Chloroquine-resistant p. vivax:
Mefloquine

70
Q

treating severe malaria in pregnancy

A
  • 1st trimester: Quinidine or artesunate
  • 2nd/3rd trimester:
    • 1st option: Artesunate
    • 2nd option: Artemether

Pharm (6 decks)

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