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Pharmacology > Exam 3: Antimalarial Drugs > Flashcards

Exam 3: Antimalarial Drugs Flashcards

1
Q

What is the DOC for Malaria that does not have any drug resistance?

A

Chloroquine

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2
Q

What genus does Protozoa belong to?

A

Plasmodia

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3
Q

What are the 4 Protozoa species that cause malaria in humans?

A
  • P. Falciparum
  • P. Vivax
  • P. Ovale
  • P. Malariae
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4
Q

What are the two types of malaria protozoa that are dormant and stay in the liver?

A

P. Vivax and P. Ovale

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5
Q

What is the most lethal form of malaria?

A

P. Falciparum

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6
Q

What symptoms does P. Falciparum malaria cause?

A
  • Fever every 3rd day
  • Severe blood loss anemia
  • Cerebral malaria (clogs vessels in the brain)
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7
Q

What is the most common form of malaria?

A

P. Vivax

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8
Q

What are the malaria species called when they are dormant in the liver?

A

Hyponozoites

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9
Q

What symptoms does malaria caused by P. Vivax cause?

A
  • Chills and fever every 3rd day

- Relapses months to years after mosquito bite due to dormant forms

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10
Q

What is the most rare form of malaria?

A

P. Ovale

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11
Q

What are the two types of malaria that cause relapses and why?

A

P. Ovale and P. Vivax because they have dormant stages in the liver and can be reactivated at any time

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12
Q

What symptoms does malaria caused by P. Malaria have?

A
  • Fever every 4th day

- Chronic infection that can last a lifetime

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13
Q

What is a clinical cure for malaria?

A

Erythrocytes forms of the parasite have been eradicated and the patient is symptom free (Dormant Protozoa in the liver do no get eradicated)

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14
Q

What is a radical cure for malaria?

A

All forms of the parasite, including any secondary tissue forms have been eradicated.
-Infections by P. Vivax and P. Ovale need radical cures

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15
Q

What do blood schizonticides do?

A

They act on erythrocytes forms of the malaria parasite and can be used to suppress symptoms and provide a so-called “clinical cure”
-Does NOT affect secondary tissue forms of P. Vivax or P. Ovale

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16
Q

What do tissue schizonticides do?

A

Eliminate the Protozoa from the tissue (acts on the dormant hepatic stages)

  • Does not suppress symptoms once erythrocytes stages have been established
  • Prevents relapse
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17
Q

If you have a patient with a dormant form of malaria, how should you treat them?

A

A blood and a tissue schizonticide

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18
Q

What are the recommended treatments for uncomplicated malaria with a chloroquine resistance?

A

Artesunate + Atovoquone/proguanil

OR

Artemether-lumefantrine

“ACT” drugs

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19
Q

How does malaria form resistance against Chloroquine?

A

Transport pumps

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20
Q

What is the MOA of Chloroquine?

A

Interferes with lysosomal degradation of hemoglobin

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21
Q

How is chloroquine absorbed and what inhibits its absorption?

A

Taken orally, absorbed in the GI tract.

-Mg+ and Ca+ antacids inhibit absorption

22
Q

Where does chloroquine accumulate once absorbed? What can this cause?

A

Melanin-rich tissues, like the skin and retina.

This can cause retinal and cornea toxicity and is contraindicated in patients with ocular disease

23
Q

How is chloroquine metabolized?

A

In the liver by a substrate of CYP34A

24
Q

What are the toxicities associated with chloroquine?

A

Retinal and corneal toxicity, hemolysis (G6PD patients), and QT prolongation

25
Q

What are the contraindications of Chloroquine?

A

Patients with ocular disease, psoriasis, and porphyria

26
Q

What drugs have the fastest action against P. Falciparum?

A

The artemisinin - artesunate and artemether

**They do have a short half life and are always combined with other antimalarial drugs

27
Q

What type of drugs are Proguanil and pyrimethamine + sulfadoxine?

What type of malaria do they attack?

A

Folate metabolism inhibitors

Main effect on erythrocytic forms

28
Q

How does resistance develop against the folate metabolism inhibitors?

A

Mutations in Dihydrofolate reductase

29
Q

What is the MOA of the folate metabolism inhibitors?

A

Suldadoxine inhibits the incorporation of PABA into the folic acid.

Pyrimethamine and proguanil inhibit dihydrofolate reductase, blocking conversion of dihydrofolate reductase into tetrahydrofolic acid

30
Q

What antimalarials are often used in conjunction with artemisinins?

A

Atovoquone, lumefantrine, mefloquine, and sulfadoxine-pyrimethamine

31
Q

What is the MOA of Atovoquone + Proguanil?

A
  • Atovoquone interferes with mitochondrial electron transport, ATP, and pyrimidine biosynthesis
  • Proguanil- Prodrug that is converted to cycloguanil, inhibits dihydrofolate reductase

Together, they are synergistic

32
Q

What is Atovoquone + Proguanil often combined with and why?

A

Artesunate for rapid clearance and decrease in resistance

33
Q

What are the side effects of Atovoquone + Proguanil that require discontinuation of the drug?

A

Rash, fever, vomiting, diarrhea

*caution with pregnancy, caused mutations in mouse tests

34
Q

What is lumefantrine used in combination with?

A

Artemether

35
Q

What are the toxicities associated with lumefantrine?

A

Headache (56%) and QT prolongation

36
Q

What kind of malaria does Quinine and Quinidine gluconate treat?

A

Complicated, chloroquine resistance plasmodia

37
Q

What is Quinine and Quinidine Gluconate often combined with and why?

A

Doxycycline, tetracycline, or Clindamycin because it reduces the length of the treatment and therefore the adverse side effects are reduced

38
Q

What is important to remember about the dosing for Quinine?

A

It have a very narrow margin between effective dose and toxic dose

39
Q

What are the toxicities associated with quinine and quinidine Gluconate?

A
  • Cinchonism: Tinnitus, headache, dizziness, flushing, visual disturbance
  • Anti-arrhythmic agent
  • Hemolysis in G6PD deficient patients
  • QT prolongation
  • Diarrhea
40
Q

What form of malaria do antibiotics help treat?

A

Complicated, chloroquine-resistance malaria (quinine and Clindamycin in children/pregnant women)

41
Q

What form of malaria does Mefloquine act on?

A

Erythrocytic forms, however resistance and toxicity limits use (drug of last resort)

42
Q

How is Mefloquine metabolized?

A

Absorbed in the GI tract with a bioavailability greater than 85%, metabolized in the liver, and eliminated very slowly via bile in the feces (permits single dose regimen)

43
Q

What are the toxicities associated with Mefloquine?

A

Depression of the myocardium (do NOT combine with quinine!)
Seizures
Latent psychosis
Vivid dreams

44
Q

When is mefloquine not recommended?

A

Should not be used in patients with mental illness or epilepsy
Not recommended in pregnancy due to teratogenicity

45
Q

When is pyrimethamine + sulfadoxine used for malaria tx?

A

Empirical treatment and preventative intermittent therapy in pregnant women

46
Q

What type of drug is Primaquine?

A

Tissue schizonticide- only active against tissue forms.

47
Q

What are the contraindications of Primaquine?

A

SLE or RA (granulocytopenia)

*not recommended in pregnancy, infancy, breastfeeding due to fatal hemolytic anemia (G6PD status of baby is unknown)

48
Q

What is the major toxicity associated with Primaquine?

A

Hemolytic anemia in G6PD patients

49
Q

What type of drug is Tafenoquine?

A

Tissue schizonticide against against ALL stages of disease

50
Q

What are the contraindications of Tafenoquine?

A

G6PD deficiency or G6PD status is unknown

51
Q

What are the uses of Tafenoquine in malaria tx?

A

Used as a radical cure and terminal prophylaxis

52
Q

What is Cinchonism and what drug is it associated with?

A

Tinnitus, headache, dizziness, flushing, visual disturbance

-Quinine/Quinidine

Pharmacology (25 decks)

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