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Pharmacology > Anti-malarial drugs > Flashcards

Anti-malarial drugs Flashcards

1
Q

Four species of plasmodium typically cause human malaria

A

Plasmodium falciparum
P vivax
P malariae
P ovale

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2
Q

Which specie is responsible for the majority of serious complications and deaths?

A

P falciparum

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3
Q

Malaria

-Parasite life cycle

A
  1. mosquito inoculates sporozoites to initiate human infection
  2. sporozoites invade liver cells –> exoerythrocytic stage: tissue schinzonts mature in the liver
  3. from liver –> merozoites. Only erythrocytic parasites cause clinical illness
  4. Sexual stage gametocytes also develop in erythrocytes before being taken up by mosquitoes, where they develop into –> infective sporozites
  5. in P falciparum and P malariae infection, treatment that eliminates erythrocytic parasites will cure these infections
  6. in P vivax and P ovale infections, a dormant hepatic stage, the hypnozoite, is not eradicated by most drugs and relapses can occur
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4
Q
  1. Which stage of infections causes clinical malaria?

2. All effective antimalarial treatment are?

A
  1. Only the asexual erythrocytic stage

2. Blood schinzonticides that kill this stage

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5
Q

Only drug that is able to kill quiescent hypnozoites

A

Primaquine

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6
Q

Drugs that act on hepatic schizonts during initial infection

A

Atovaquone-proguanil

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7
Q

Drugs that act on blood-stage schinzonticides

A

Atovaquone–proguanil,
Doxycycline,
Mefloquine,
Chloroquine

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8
Q

Antimalarial drugs

-treatment

A
  • Chloroquine –> most nonfalciparum and falciparum infections from areas without known resistance
  • Malarone (atavaquone and proguanil) –> uncomplicated falciparum malaria from most areas
  • Mefloquine, quinine, halofantrine –> against resistant falciparum malaria
  • Intravenous artesunate, quinidine, quinine –> severe falciparum malaria
  • Primaquine –> Vivax and ovale malaria, to eradicate liver forms
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9
Q

Chloroquine

  • pharmacokinetics
  • action
A

-initial 1/2 life of 3-5 days but much longer terminal elimination 1/2 of 1-2 month

  • effective against blood and gameto forms
  • preventing the biocrystallization of the hemoglobin breakdown product heme into hemozoin –> accumulation of heme is toxic to the parasite
  • highly effective blood schonzonticide
  • not active against liver stage
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10
Q

Chloroquine

  • basis of resistance
  • clinical uses
A

-mutations in putative transporter

  • chemoprophylaxis of malaria, amebic liver abscesses, rheumatological diseases
  • treatment of uncomplicated malaria,
  • rapidly terminates fever and clears parasitemia,
  • does not eliminate dormant liver forms of P vivax and P ovale –> primaquine
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11
Q

Chloroquine

-adverse effects

A
  • usually well tolerated
  • ECG changes, severe hypotension, dermatitis

-safe in pregnancy and for young children

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12
Q

Quinine

  • pharmacokinetics
  • action
A

-effective in blood and gameto forms

  • mechanism of action is unknown
  • gametocidal against P vivax and P ovale
  • not active against liver stage parasites
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13
Q

Quinine

-clinical uses

A
  • treatment of severe palciparum malaria (i/v)
  • treatment of falciparum malaria (oral)
  • severe, uncomplicated malaria commonly with second drug (doxycycline, in children with clindamycin)
  • generally not used for chemoprophylaxis
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14
Q

Quinine

  • unwanted effects
  • contraindications and drug interactions
A
  • cinchonism (visual and hearing disturbances, GI distress, headache, virtigo)
  • hypoglycemia
  • blackwater fever
  • underlying visual and auditory problems
  • should not be given together with mefloquine
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15
Q

Mefloquine

  • pharmacokinetics
  • action
A

-elimination 1/2 life is about 20 days

  • mechanism of action is unknown
  • strong blood schinzonticidal activity against P falciparum and P vivax
  • not active against hepatic stages or gametocytes
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16
Q

Mefloquine

  • clinical uses
  • adverse effects
A
  • uncomplicated falciparum malaria
  • combination of artesunate + mefloquine
  • chemoprophylaxis of malaria –> against most strains of P falciparum and probably all other species

-potential neurologic and psychiatric toxicities

17
Q

Mefloquine

-contraindication and drug interactions

A
  • history of epilepsy, psychiatric disorders

- should not be combined with quinine and mefloquine

18
Q

Artesunate

  • pharmacokinetics
  • action
A
  • water soluble, oral, i/v, rectal
  • not useful for chemoprophylaxis because of their short 1/2 lives
  • effective against blood forms
  • metabolized in the food vacuole of the parasite and forming toxic free radicals
  • rapidly acting on blood schinzonticides against all malaria parasites
  • no effect on hepatic stages
19
Q

Artesunate

  • clinical uses
  • adverse effects
  • pregnancy
A
  • first line treatment of uncomplicated falciparum malaria
  • treatment of complicated falciparum malaria

-very well tolerated

  • uncomplicated falciparum malaria: second and third trimester of pregnancy
  • severe malaria in first, second and third trimesters
20
Q

Primaquine

-action

A
  • mechanism of action is unknown
  • active against hepatic stages of malaria parasites
  • active against the dormant hypnozoite stages of P vivax and P ovale
  • gametocidal against the four malaria species
  • weak activity against erythrocytic stage parasites

liver, hypno and gameto stages

21
Q

Primaquine

-clinical uses

A
  • chemoprophylaxis of malaria - only when mefloquine, atovaquone and proguanil, doxycycline cannot be used
  • treatment of acute vivax and ovale malaria (radical cure)
  • terminal prophylaxis vivax and ovale malaria a
  • gametocidal action
  • Pneumocystis Jiroveci infection
22
Q

Primaquine

  • adverse effects
  • contraindications and cautions
  • pregnancy
A
  • generally well tolerated, hemolysis or methemoglobinemia (manifested by cyanosis), especially with G6PD deficiency
  • should be tested for G6PD deficiency –> if positive, use chloroquine
  • should be avoided!
23
Q

Atovaquone

-action

A
  • disrupt mitochondrial electron transport
  • active against tissue and erythrocytic schizonts, allowing chemoprophylaxis to be discontinued only 1 week after the end of exposure (compared with 4 weeks for mefloquine or doxycycline, which lack activity against tissue schizonts)
  • effective in the blood and liver stages
24
Q

Atovaquone

-clinical uses

A
  • acute, uncomplicated P falciparum malaria
  • chemoprophylaxis of malaria
  • Pneumocystis Jiroveci infection
25
Q

Inhibitors of folate synthesis

  • name
  • pharmacokinetics
  • action
A
  • Proguanil (atovaquone and proguanil)
  • 1/2 life is about 16h - for chemoprophylaxis daily
  • proguanil –> some activity against hepatic forms
26
Q

Inhibitors of folate synthesis

  • clinical uses
  • adverse effect
A
  • treatment of chloroquine- resistant falciparum malaria
  • intermittent preventive therapy
  • chemoprophylaxis of malaria - not recommended
  • toxoplasmosis - first line therapy
  • Pneumocystis Jiroveci infection - first line therapy
  • generally very well tolerated
  • safe to be used in pregnancy
27
Q

Doxycycline

-clinical uses

A
  • treatment of falciparum malaria with quinine
  • chemoprophylaxis of malaria
  • effective in the blood form

Pharmacology (29 decks)

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