Antiprotozoals

Question 1

Name 2 Artemesinins

Answer 1

Artemether-lumefantrine and Artesunate

Question 2

Name 2 Quinolines

Answer 2

Mefloquine and Quinine

Question 3

Name the Biguanide combination

Answer 3

Atovaquone-proguanil

Question 4

Which 3 drug groups are Antimalarials?

Answer 4

Artemesinins
Quinolines
Biguanide combination

Question 5

What is the classification of Quinine?

Answer 5

Quinoline

Antimalarial

Question 6

What is the mechanism of action of Quinine?

Answer 6

Inhibits the parasite’s haem polymerase and forms a hydrogen-bonded complex with double-stranded DNA. This leads to inhibition of strand separation, transcription and protein synthesis.

Question 7

What are the therapeutic indications of Quinine? (4)

Answer 7

• Malaria suppression and treatment
• Erythrocytic forms of all 4 plasmodia
• No effect on the dormant forms or on the gametocytes of P. falciparum
• Main treatment of P. falciparum

Question 8

How is Quinine administered?

Answer 8

Orally over 7 day course, or slow IV infusion

Question 9

Describe the absorption of Quinine

Answer 9

well absorbed from GIT

Question 10

Describe the metabolism of Quinine

Answer 10

metabolized in the liver

Question 11

Describe the excretion of Quinine

Answer 11

Metabolites are excreted in the urine within 24 hours

Question 12

What is the half-life of Quinine?

Answer 12

10 hours

Question 13

What are the adverse effects of Quinine? (5)

Answer 13

• irritant to the gastric mucosa and can cause nausea and vomiting and epigastric pain
• “cinchonism” (nausea, dizziness, tinnitis, headache and blurring of vision)
• hypotension
• cardiac dysrhythmias
• severe central nervous system disturbances

Question 14

What is the classification of Mefloquine?

Answer 14

Quinoline

Antimalarial

Question 15

What is the mechanism of action of Mefloquine?

Answer 15

Inhibits the haem polymerase

Question 16

What are the therapeutic indications of Mefloquine?

Answer 16

• P. falciparum
• P. vivax
• Prophylaxis and treatment of chloroquine- resistant and multidrug-resistant falciparum malaria

Question 17

How is Mefloquine administered?

Answer 17

orally

Question 18

Describe the absorption of Mefloquine

Answer 18

rapidly absorbed

Question 19

What is the half-life of Mefloquine?

Answer 19

up to 30 days

Question 20

What is the main adverse effect of Mefloquine?

Answer 20

GIT disturbances

Question 21

What is a contraindication of Mefloquine?

Answer 21

pregnancy

Question 22

What is the classification of Atovaquone and Proguanil?

Answer 22

Folate antagonists
Biguanide combination
Antimalarial

Question 23

What is the mechanism of action of Atovaquone?

Answer 23

Selectively inhibits the parasitic electron transport chain

Question 24

What is the mechanism of action of Proguanil?

Answer 24

Inhibits the enzyme dihydrofolate reductase in the parasite

Question 25

What are the therapeutic indication for Atovaquone and Proguanil?

Answer 25

- chloroquine and multi-drug resistant strains of P. falciparum and P. vivax - prophylaxis

Question 26

How is Atovaquone and Proguanil administered?

Answer 26

orally (in combination with others)

Question 27

What is the half-life of Atovaquone?

Answer 27

2-3 days

Question 28

What is the half-life of Proguanil?

Answer 28

16 hours

Question 29

What are the adverse affects of Atovaquone and Proguanil?

Answer 29

very few in therapeutic doses

Question 30

What is the mechanism of action of Artemesinins?

Answer 30

Ativated by free or haem-bound iron causing the production of a reactive radical which leads to alkylation of proteins and haem in the parasite

Question 31

What are the therapeutic indications of Artesunate?

Answer 31

used intravenously for the management of severe malaria

Question 32

What are the therapeutic indications of Artemether and Lumefantrine?

Answer 32

used in combination for management of mild malaria (orally)

Question 33

What are the 2 adverse effects of Artemesinins?

Answer 33

- Neurotoxicity: most common effect are headache and dizziness. - Cardiotoxicity: may cause elongated QT interval.

Question 34

What is the classification of Mebendazole?

Answer 34

Anthelmintic | Antinematodal

Question 35

What is the mechanism of action of Mebendazole?

Answer 35

Binds to free beta-tubulin, inhibiting its polymerization and thus interfering with microtubule-dependent glucose uptake in the worm

Question 36

What are the therapeutic indications of Mebendazole?

Answer 36

first choice agent against nematodes

Question 37

What is the spectrum of activity of Mebendazole?

Answer 37

broad

Question 38

What are the adverse effects Mebendazole? (2)

Answer 38

- in children infested with large numbers of Ascaris worms: Nausea and vomiting, abdominal pain and diarrhoea - normal doses: few adverse effects

Question 39

What are the contraindications of Mebendazole?

Answer 39

Pregnancy: embryotoxic and teratogenic

Question 40

Describe the absorption of Mebendazole

Answer 40

Less than 10% of mebendazole is absorbed after oral administration, the absorbed agent is more than 90% bound to plasma proteins

Question 41

Describe the metabolism of Mebendazole

Answer 41

rapidly metabolized in the liver to inactive metabolites

Question 42

Describe the excretion of Mebendazole?

Answer 42

excreted in the urine and the bile within 24-48 hours

Question 43

How can the absorption of Mebendazole be increased?

Answer 43

when it is taken with a fatty meal