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What is the mechanism of action of Quinine?
What is the mechanism of action of Quinine?
Which of the following Antiprotozoal Drugs is effective against multidrug-resistant P.falciparum?
Which of the following Antiprotozoal Drugs is effective against multidrug-resistant P.falciparum?
What is the half-life of Mefloquine?
What is the half-life of Mefloquine?
What is the primary route of excretion for Mefloquine?
What is the primary route of excretion for Mefloquine?
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What is a common adverse effect of Quinine treatment?
What is a common adverse effect of Quinine treatment?
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What is the name of the plant from which Artemisinin is derived?
What is the name of the plant from which Artemisinin is derived?
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What is the primary mechanism of action of chloroquine in malaria treatment?
What is the primary mechanism of action of chloroquine in malaria treatment?
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What is the primary concern regarding the use of chloroquine in malaria treatment?
What is the primary concern regarding the use of chloroquine in malaria treatment?
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What is the characteristic of chloroquine's volume of distribution?
What is the characteristic of chloroquine's volume of distribution?
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What is the mechanism of action of artemisinin derivatives?
What is the mechanism of action of artemisinin derivatives?
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Why are artemisinin derivatives not used for prophylaxis?
Why are artemisinin derivatives not used for prophylaxis?
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What is the indication for using atovaquone-proguanil combination?
What is the indication for using atovaquone-proguanil combination?
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What is the advantage of using artemisinin derivatives in combination with other drugs?
What is the advantage of using artemisinin derivatives in combination with other drugs?
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What is the primary mechanism of action of atovaquone?
What is the primary mechanism of action of atovaquone?
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What is the adverse effect of chloroquine that may occur when used with certain drugs?
What is the adverse effect of chloroquine that may occur when used with certain drugs?
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What is a common adverse effect of pyrimethamine?
What is a common adverse effect of pyrimethamine?
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What is the mechanism of action of chloroquine?
What is the mechanism of action of chloroquine?
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What is amodiaquine used for?
What is amodiaquine used for?
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Study Notes
Metabolism and Adverse Effects of Antimalarial Drugs
- Proguanil is metabolized by CYP2C19, and genetic polymorphisms may affect its metabolism.
- Adverse effects of proguanil include GI effects (nausea/vomiting/diarrhea, abdominal pain, anorexia), headache, and dizziness.
Mefloquine
- Mefloquine is effective as monotherapy for prophylaxis and treatment of multidrug-resistant P. falciparum.
- Resistant strains are prevalent in Southeast Asia.
- Mechanism of action is unknown.
- Mefloquine is well absorbed and widely distributed, undergoes entero-hepatic circulation, and has a half-life of 20 days.
- Adverse effects include nausea, vomiting, disorientation, hallucinations, and depression.
Quinine
- Quinine was originally isolated from the bark of the Cinchona tree.
- It interferes with heme polymerization, but its exact mechanism is unknown.
- Quinine is a blood schizonticide and gametocidal against P. vivax and P. ovale.
- It is reserved for severe cases (e.g., cerebral malaria) and for chloroquine-resistant cases.
- Adverse effects include nausea, vomiting, tinnitus, and vertigo.
Artemisinin
- Artemisinin is a derivative of the "sweet wormwood plant" and is recommended as a first-line treatment for multi-drug-resistant P. falciparum.
- It is used for prophylaxis of malaria and treatment of extra-intestinal amebiasis.
- Artemisinin derivatives cannot be used for prophylaxis due to their short half-life.
Chloroquine
- Chloroquine is completely and rapidly absorbed after oral administration and has a large volume of distribution.
- It penetrates CSF and crosses the placenta.
- Metabolism occurs in the liver, and some metabolic products have anti-malarial activity.
- Excretion occurs through the kidney.
- Resistance to chloroquine has become a serious medical problem in Africa, Asia, and Central and South America.
Adverse Effects of Chloroquine
- Chloroquine is a safe drug, but adverse effects occur at high doses.
- Adverse effects include gastrointestinal upset, blurred vision, and discolored nail beds after long-term use.
Atovaquone-Proguanil
- The combination of atovaquone-proguanil is effective for chloroquine-resistant strains of P. falciparum.
- Atovaquone inhibits mitochondrial processes, such as electron transport chain, thereby inhibiting ATP biosynthesis.
- Proguanil is a prodrug that inhibits dihydrofolate reductase, preventing DNA synthesis.
Mechanism of Action of Artemisinin
- Artemisinin's endoperoxide bond is cleaved by heme iron in the parasite's food vacuole, leading to the production of free radicals.
- The drug also binds to and damages parasite's proteins.
Prevention of Resistance
- Artemisinin derivatives are used in combination with other drugs to prevent resistance.
Pyrimethamine
- Pyrimethamine is a blood schizonticide and a strong sporozonticide.
- It is used in combination with sulfadoxine for treatment of P. falciparum malaria.
- Adverse effects include megaloblastic anemia (reversible with leucovorin).
Treatment and Prevention of Malaria
- Chloroquine-resistant areas: atovaquone-proguanil, doxycycline, and artemisinin derivatives are used for treatment and prevention.
- Chloroquine-sensitive areas: chloroquine is used for treatment and prevention.
- Prevention of relapse of P. vivax and P. ovale: primaquine is used.
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Description
This quiz covers the use of chloroquine in malaria prophylaxis and treatment of extra-intestinal amebiasis, as well as its pharmacokinetics and mechanism of action.
