Pharmacology > Antimalarials > Flashcards

Antimalarials Flashcards

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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
\_\_\_ is the only medication recommended for chemoprophylaxis in **pregnant women in chloroquine-resistant areas**
**mefloquine** is the only medication recommended for chemoprophylaxis in **pregnant women in chloroquine-resistant areas**
26
\_\_\_ and ____ are used in treatment of uncomplicated malaria in regions of **Southeast Asia**
**mefloquine** and **artesunate** are used in treatment of uncomplicated malaria in regions of **Southeast Asia**
27
describe mefloquine pharmokinetics
* oral only * t1/2 = 20 days * **weekly prophylactic dosing**
28
describe mefloquine AEs
* serious neurological and psychiatric toxicities: * dizziness, loss of balance * ringing in the ears * anxiety, depression * hallucinations
29
contrast mefloquine AEs with **weak vs high dosing**
* weak dose * nausea, vomiting, diarrhea * dizziness * sleep and behavioral disturbances * rash * high dose * leukocytosis * thrombocytopenia * aminotransferase elevations * arrhythmias * bradycardia
30
mefloquine is contraindicated in patients with history of
* epilepsy * psychiatric disorders * arrhythmia, cardiac conduction defects * sensitivity to related drugs
31
mefloquine should NOT be coadministered with
quinine/quinidine halofantrine
32
DOC for eradication of **dormant liver forms of p. vivax and p. ovale?**
Primaquine
33
describe the clincal applications for Primaquine
* **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
describe primoquines AE
* **Hemolysis or methemoglobinemia** (especially in G6PD deficient patients * primaquine oxidizes GSH to GSSG → less GSH available to neutralize toxic compounds
35
patients should be tested for ____ before prescribing _primaquine_ ## Footnote *withhold treatment if severely deficient*
patients should be tested for **G6PD deficiency** before prescribing _primaquine_ ## Footnote *withhold treatment if severely deficient*
36
can you give primaquine to pregnant women?
NO!
37
**Malarone** = ____ + \_\_\_\_ clinal application?
atovaquone + proguanil treatment & prophylaxis for p. falciparum
38
_malarone_ is active against _____ and ____ schizonts
_malarone_ is active against **tissue** and **erythrocytic** schizonts
39
\_\_\_ should be used 1-2 days before travel and discontinued 1 week after exposure
**Malarone** should be used 1-2 days before travel and discontinued 1 week after exposure
40
Malarone disrupts ____ and is taken \_\_\_
Malarone disrupts **mitochondrial electron transport** and is taken **orally**
41
can you use malarone during pregnancy?
NOPE!
42
list inhibitors of folate synthesis
* pyrimethamine * proguanil * sulfadoxine
43
describe the clincal application of folate synthesis inhibitors
* **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
_Pyrimethamine_ + _Proguanil_ act slowly against ____ forms of all malaria species
_Pyrimethamine_ + P**_roguanil_** act slowly against **erythrocytic** forms of all malaria species
45
\_\_\_\_ (a folate synthesis inhibitor) has some activity against *hepatic* forms
**proguanil** (a folate synthesis inhibitor) has some activity against *hepatic* forms
46
\_\_\_, a folate synthesis inhibitor, are weakly active against *erythrocytic* schizonts
**sulfonamides,** a folate synthesis inhibitor, are weakly active against *erythrocytic* schizonts
47
which folate synthesis inhibitors act where?
48
**Proguanil** AEs
* mouth ulcers * alopecia = rare
49
Pyrimethamine-Sulfadoxine AEs
* erythema multiforme * Steven-Johnson syndrome * toxic epidermal necrolysis
50
Sulfadoxine AEs
* hematologic * GI, CNS, dermatologic & renal toxicity
51
which FSIs are safe/unsafe in pregnancy?
* Safe: * proguanil * pyrimethamine-sulfadoxine * Not safe: * sulfonamides
52
**Doxycyline** is active against ___ schizonts of all malaria parasites but not against ____ stage
**Doxycyline** is active against **erythrocytic** schizonts of all malaria parasites but not against **liver** stage
53
\_\_\_\_\_ 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
**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
Doxycylcine AEs
* GI, candidal vaginitis, **photosensitivity** * **discoloration & hypoplasia of teeth, stunting of growth** * Fatal hepatotoxicity (in pregnancy)
55
Doxycycline contraindications
**pregnancy or children \< 8y** (FDA Category D)
56
Artemisinin variations
* Artesunate, Artemether, Dihydroartemisinin * **Coartem:** artemether + lumefantrine
57
\_\_\_\_ 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.
**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
Artem**i**s**i**n**i**n binds to ____ → breaks down peroxide bridges → produces ___ → damages parasite proteins It has a ___ half life
Artem**i**s**i**n**i**n binds to **iron** → breaks down peroxide bridges → produces **free radicals** → damages parasite proteins It has a **very short** half life
59
Artemisinin AEs
* 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
\_\_\_ can be used as an alternative to doxycycline
**Clindamycin** can be used as an alternative to doxycycline
61
_Halofantrine_ is effective against ____ stages of all parasites Use is limited by irregular absorption, cardiac toxicity, and is \_\_\_\_\_
_Halofantrine_ is effective against **erythrocytic** stages of all parasites Use is limited by irregular absorption, cardiac toxicity, and is **Teratogenic**
62
describe **lumefantrine**
* Effective against **erythrocytic** stages of all parasites * Available only as fixed-dose combination with **artemether** * Causes minor QT prolongation (clinically insignificant) * Well tolerated
63
Safe vs unsafe drugs in pregnancy
* **Safe:** Mefloquine, Proguanil, Chloroquine, Primethamine-Sulfadoxe, Artemisins * **Unsafe/Contraindicated:** Malarone, Primalquine, Sulfonamides
64
Recommended drug(s) for - P. malariae (all regions, no resistance) **-** P. falciparum with no resistance
chloroquine
65
Recommended drug(s) for **P. falciparum** with **chloroquine-resistance?**
1. **Atovaquone-proguanil (Malarone)** 2. **Artemether-lumefantrine (coartem)** 3. Quinine + Doxycycline 4. Mefloquine
66
Recommended drug(s) for **p. vivax/ovale** (no resistance, all regions)
Chloroquine/Hydroxychloroquine + Primaquine Why?? Primaquine = one of few drugs acting in **hepatic** stage
67
Recommended drug(s) for **P. vivax** with **chloroquine-resistance**
1. Quinine + Doxycycline + **primaquine** 2. Atovaquone-Proguanil + **primaquine** 3. Mefloquine + **primaquine**
68
treating severe malaria of all species, all regions
**IV: Quinidine & Doxycycline or Clindamycin** or IV: Artesunate followed by Atovaquone-Proguanil, Clindamycin, or Mefloquine | (can progress to oral quinine + doxycycline)
69
treating uncomplicated malaria in pregnancy
**Chloroquine-sensitive:** chloroquine/hydrochloroquine * *Chloroquine-resistant p. falciparum:** 1. Mefloquine 2. Quinine+clindamycin **Chloroquine-resistant p. vivax:** Mefloquine
70
treating severe malaria in pregnancy
* 1st trimester: **Quinidine or artesunate** * 2nd/3rd trimester: * 1st option: **Artesunate** * 2nd option: **Artemether**
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