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🦠microbiology review

Primaquine

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Primaquine is an antimalarial drug that is primarily used to prevent and treat Plasmodium vivax and Plasmodium ovale malaria infections. It is effective against the dormant liver stage of these parasites, known as hypnozoites, which can cause relapses of malaria even after initial treatment.

5 Must Know Facts For Your Next Test

  1. Primaquine is the only FDA-approved drug that can eliminate the hypnozoite stage of Plasmodium vivax and Plasmodium ovale, preventing relapses of malaria.
  2. Primaquine is often used in combination with other antimalarial drugs, such as chloroquine or artemisinin-based combination therapies, to provide a complete cure for P. vivax and P. ovale infections.
  3. Primaquine can cause hemolytic anemia in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency, a genetic disorder, and therefore requires careful monitoring and dosage adjustments.
  4. Primaquine is also used as a prophylactic agent to prevent malaria in individuals traveling to endemic areas, particularly in combination with other antimalarial drugs.
  5. The mechanism of action of primaquine involves the generation of reactive oxygen species that disrupt the metabolism and structure of the Plasmodium parasites, leading to their destruction.

Review Questions

  • Explain the role of primaquine in the treatment of Plasmodium vivax and Plasmodium ovale malaria infections.
    • Primaquine is a crucial antimalarial drug that targets the dormant liver stage of Plasmodium vivax and Plasmodium ovale parasites, known as hypnozoites. These hypnozoites can cause relapses of malaria even after initial treatment with other antimalarial drugs. By eliminating the hypnozoites, primaquine prevents these relapses and provides a complete cure for P. vivax and P. ovale infections. Primaquine is often used in combination with other antimalarial drugs to ensure a comprehensive treatment approach.
  • Describe the potential side effects and precautions associated with the use of primaquine.
    • One of the primary concerns with primaquine is its ability to cause hemolytic anemia in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency, a genetic disorder. This condition can lead to the destruction of red blood cells, resulting in anemia. Therefore, healthcare providers must carefully assess a patient's G6PD status before prescribing primaquine and monitor them closely during treatment. Dosage adjustments may be necessary to minimize the risk of adverse effects. Additionally, primaquine can interact with certain other medications, and its use may be contraindicated in specific medical conditions, requiring close medical supervision.
  • Analyze the mechanism of action of primaquine and its significance in the context of antimalarial drug development.
    • The mechanism of action of primaquine involves the generation of reactive oxygen species that disrupt the metabolism and structure of the Plasmodium parasites, leading to their destruction. This unique mechanism of action, targeting the dormant liver stage of the parasites, sets primaquine apart from other antimalarial drugs that primarily focus on the blood stage of the infection. The ability of primaquine to eliminate the hypnozoites and prevent relapses of malaria is a crucial feature in the fight against this disease. Understanding the mechanism of action of primaquine and its specific targeting of the liver stage parasites has informed the development of other antimalarial drugs with similar or complementary mechanisms, contributing to the ongoing efforts to improve the treatment and prevention of malaria.