Antimalarial drugs – classification and mechanism MCQs With Answer

Antimalarial drugs – classification and mechanism MCQs With Answer

Antimalarial drugs encompass diverse classes—quinolines, artemisinins, antifolates, 8‑aminoquinolines, atovaquone combinations and antibiotics—each with distinct mechanisms such as inhibition of heme polymerization, generation of free radicals, DHFR/DHPS blockade and cytochrome bc1 inhibition. Understanding blood schizonticides, tissue schizonticides, gametocytocidal and hypnozoitocidal actions, pharmacokinetics, resistance mechanisms (pfcrt, cytochrome b, DHFR mutations) and safety issues (G6PD deficiency, pregnancy, neurocardiac effects) is essential for B.Pharm students. This concise, keyword‑rich primer prepares you for clinical application and exam questions. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which of the following is a 4‑aminoquinoline antimalarial?

• Chloroquine
• Mefloquine
• Primaquine
• Artemisinin

Correct Answer: Chloroquine

Q2. The primary mechanism of action of chloroquine is:

• Inhibition of dihydrofolate reductase
• Generation of free radicals via endoperoxide cleavage
• Inhibition of heme polymerization (hemozoin formation)
• Blockade of mitochondrial cytochrome bc1 complex

Correct Answer: Inhibition of heme polymerization (hemozoin formation)

Q3. Artemisinin derivatives exert antimalarial activity mainly by:

• Reversible inhibition of protein synthesis
• Cleavage of an endoperoxide bridge producing free radicals
• Competitive antagonism at dihydropteroate synthase
• Direct inhibition of plasmodial DNA gyrase

Correct Answer: Cleavage of an endoperoxide bridge producing free radicals

Q4. Which drug primarily inhibits plasmodial dihydrofolate reductase (DHFR)?

• Pyrimethamine
• Sulfadoxine
• Atovaquone
• Quinine

Correct Answer: Pyrimethamine

Q5. Atovaquone’s antimalarial mechanism targets:

• Heme polymerization
• Mitochondrial cytochrome bc1 complex (electron transport)
• Folate synthesis at DHPS
• 30S ribosomal subunit

Correct Answer: Mitochondrial cytochrome bc1 complex (electron transport)

Q6. Which antimalarial is effective against hypnozoites of Plasmodium vivax and P. ovale?

• Chloroquine
• Primaquine
• Mefloquine
• Doxycycline

Correct Answer: Primaquine

Q7. A major adverse effect of primaquine is hemolysis in patients with:

• Porphyria
• G6PD deficiency
• Renal failure
• Hyperthyroidism

Correct Answer: G6PD deficiency

Q8. Which combination is commonly recommended for treatment and prophylaxis of chloroquine‑resistant P. falciparum?

• Chloroquine plus primaquine
• Atovaquone‑proguanil
• Sulfadoxine alone
• Dapsone monotherapy

Correct Answer: Atovaquone‑proguanil

Q9. Which antimalarial is primarily gametocytocidal against mature P. falciparum and used to reduce transmission?

• Artemether
• Primaquine
• Chloroquine
• Doxycycline

Correct Answer: Primaquine

Q10. Chloroquine resistance in P. falciparum is most commonly associated with mutations in:

• pfcrt gene (chloroquine resistance transporter)
• dhfr gene
• cytochrome b gene
• 16S rRNA

Correct Answer: pfcrt gene (chloroquine resistance transporter)

Q11. Doxycycline’s antimalarial action is mainly due to inhibition of:

• Plasmodial DHFR
• 30S ribosomal subunit protein synthesis
• Heme polymerization
• Plasmodial fatty acid synthase

Correct Answer: 30S ribosomal subunit protein synthesis

Q12. Which antimalarial is well known for neuropsychiatric adverse effects?

• Mefloquine
• Chloroquine
• Artesunate
• Sulfadoxine

Correct Answer: Mefloquine

Q13. For malaria prophylaxis in pregnancy in areas with chloroquine‑sensitive malaria, the preferred drug is:

• Primaquine
• Chloroquine
• Doxycycline
• Atovaquone‑proguanil

Correct Answer: Chloroquine

Q14. Which drug is classified as a tissue schizonticide (acts on hepatic stages)?

• Primaquine
• Quinine
• Lumefantrine
• Chloroquine

Correct Answer: Primaquine

Q15. In the combination sulfadoxine‑pyrimethamine, sulfadoxine inhibits:

• Dihydrofolate reductase (DHFR)
• Dihydropteroate synthase (DHPS)
• Cytochrome bc1
• Heme polymerization

Correct Answer: Dihydropteroate synthase (DHPS)

Q16. The partner drug lumefantrine primarily works by:

• Inhibiting heme polymerization similar to quinolines
• Inhibiting mitochondrial DNA replication
• Blocking folate uptake
• Stimulating host immune clearance

Correct Answer: Inhibiting heme polymerization similar to quinolines

Q17. Cinchonism (tinnitus, headache, visual disturbance) is classically associated with overdose of:

• Quinine
• Primaquine
• Atovaquone
• Doxycycline

Correct Answer: Quinine

Q18. Which drug is contraindicated in pregnancy because of risk to the fetus due to hemolysis if the fetus is G6PD deficient?

• Primaquine
• Chloroquine
• Mefloquine
• Artesunate

Correct Answer: Primaquine

Q19. Long‑term use of pyrimethamine can cause hematological toxicity due to:

• Folate antagonism leading to megaloblastic anemia
• Direct bone marrow toxicity unrelated to folate
• Excess iron chelation
• Severe hemolysis in all patients

Correct Answer: Folate antagonism leading to megaloblastic anemia

Q20. The drug of choice for severe falciparum malaria requiring IV therapy is:

• IV artesunate
• Oral chloroquine
• IM mefloquine
• Oral doxycycline

Correct Answer: IV artesunate

Q21. Tafenoquine belongs to which antimalarial class?

• 4‑aminoquinolines
• 8‑aminoquinolines
• Artemisinins
• Antifolates

Correct Answer: 8‑aminoquinolines

Q22. Resistance to atovaquone most commonly arises from mutations in:

• pfcrt gene
• Plasmodial cytochrome b gene
• DHFR gene
• rRNA gene

Correct Answer: Plasmodial cytochrome b gene

Q23. Which of the following is an artemisinin derivative used in ACTs?

• Artesunate
• Sulfadoxine
• Halofantrine
• Primaquine

Correct Answer: Artesunate

Q24. Which antimalarial is well known to cause prolongation of the QT interval and is cardiotoxic at high doses?

• Halofantrine
• Chloroquine
• Doxycycline
• Pyrimethamine

Correct Answer: Halofantrine

Q25. A commonly used fixed‑dose artemisinin‑based combination therapy (ACT) is:

• Artemether‑lumefantrine
• Chloroquine‑primaquine
• Pyrimethamine‑atovaquone
• Sulfadoxine‑mefloquine

Correct Answer: Artemether‑lumefantrine

Q26. Which antimalarial also has a clinically important use as an antiarrhythmic agent (historical/related compound)?

• Quinidine
• Primaquine
• Atovaquone
• Mefloquine

Correct Answer: Quinidine

Q27. Which drug combination interferes with folate synthesis and is used as intermittent preventive therapy in pregnancy in some settings?

• Sulfadoxine‑pyrimethamine
• Atovaquone‑proguanil
• Chloroquine‑primaquine
• Artemether‑lumefantrine

Correct Answer: Sulfadoxine‑pyrimethamine

Q28. Which laboratory method or marker is most specific for detecting chloroquine resistance mutations in P. falciparum?

• pfcrt gene PCR mutation analysis
• Peripheral eosinophil count
• Serum bilirubin measurement
• Urine heme test

Correct Answer: pfcrt gene PCR mutation analysis

Q29. Which antimalarial class includes drugs that are primarily blood schizonticides (active against erythrocytic stages)?

• 8‑aminoquinolines only
• Quinolines and artemisinins
• Antifolates only
• All antibiotics

Correct Answer: Quinolines and artemisinins

Q30. Which antimalarial should be avoided in children under 8 years due to effects on teeth and bone growth?

• Doxycycline
• Chloroquine
• Primaquine
• Artesunate

Correct Answer: Doxycycline

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com