Antiprotozoals Flashcards
Name 2 Artemesinins
Artemether-lumefantrine and Artesunate
Name 2 Quinolines
Mefloquine and Quinine
Name the Biguanide combination
Atovaquone-proguanil
Which 3 drug groups are Antimalarials?
Artemesinins
Quinolines
Biguanide combination
What is the classification of Quinine?
Quinoline
Antimalarial
What is the mechanism of action of Quinine?
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.
What are the therapeutic indications of Quinine? (4)
- 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
How is Quinine administered?
Orally over 7 day course, or slow IV infusion
Describe the absorption of Quinine
well absorbed from GIT
Describe the metabolism of Quinine
metabolized in the liver
Describe the excretion of Quinine
Metabolites are excreted in the urine within 24 hours
What is the half-life of Quinine?
10 hours
What are the adverse effects of Quinine? (5)
- 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
What is the classification of Mefloquine?
Quinoline
Antimalarial
What is the mechanism of action of Mefloquine?
Inhibits the haem polymerase
What are the therapeutic indications of Mefloquine?
- P. falciparum
- P. vivax
- Prophylaxis and treatment of chloroquine- resistant and multidrug-resistant falciparum malaria
How is Mefloquine administered?
orally
Describe the absorption of Mefloquine
rapidly absorbed
What is the half-life of Mefloquine?
up to 30 days
What is the main adverse effect of Mefloquine?
GIT disturbances
What is a contraindication of Mefloquine?
pregnancy
What is the classification of Atovaquone and Proguanil?
Folate antagonists
Biguanide combination
Antimalarial
What is the mechanism of action of Atovaquone?
Selectively inhibits the parasitic electron transport chain
What is the mechanism of action of Proguanil?
Inhibits the enzyme dihydrofolate reductase in the parasite
What are the therapeutic indication for Atovaquone and Proguanil?
- chloroquine and multi-drug resistant strains of P. falciparum and P. vivax
- prophylaxis
How is Atovaquone and Proguanil administered?
orally (in combination with others)
What is the half-life of Atovaquone?
2-3 days
What is the half-life of Proguanil?
16 hours
What are the adverse affects of Atovaquone and Proguanil?
very few in therapeutic doses
What is the mechanism of action of Artemesinins?
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
What are the therapeutic indications of Artesunate?
used intravenously for the management of severe malaria
What are the therapeutic indications of Artemether and Lumefantrine?
used in combination for management of mild malaria (orally)
What are the 2 adverse effects of Artemesinins?
- Neurotoxicity: most common effect are headache and dizziness.
- Cardiotoxicity: may cause elongated QT interval.
What is the classification of Mebendazole?
Anthelmintic
Antinematodal
What is the mechanism of action of Mebendazole?
Binds to free beta-tubulin, inhibiting its polymerization and thus interfering with microtubule-dependent glucose uptake in the worm
What are the therapeutic indications of Mebendazole?
first choice agent against nematodes
What is the spectrum of activity of Mebendazole?
broad
What are the adverse effects Mebendazole? (2)
- in children infested with large numbers of Ascaris worms: Nausea and vomiting, abdominal pain and diarrhoea
- normal doses: few adverse effects
What are the contraindications of Mebendazole?
Pregnancy: embryotoxic and teratogenic
Describe the absorption of Mebendazole
Less than 10% of mebendazole is absorbed after oral administration, the absorbed agent is more than 90% bound to plasma proteins
Describe the metabolism of Mebendazole
rapidly metabolized in the liver to inactive metabolites
Describe the excretion of Mebendazole?
excreted in the urine and the bile within 24-48 hours
How can the absorption of Mebendazole be increased?
when it is taken with a fatty meal
