Primaquine is an 8-aminoquinoline antimalarial which eliminates the exoerythrocytic forms of malarial parasite Plasmodium vivax, Plasmodium ovale and Plasmodium falciparum by disrupting mitochondria and binding to DNA.

Primaquine's mechanism of action is not well understood. It may be acting by generating reactive oxygen species or by interfering with the electron transport in the parasite. Also, although its mechanism of action is unclear, primaquine may bind to and alter the properties of protozoal DNA.

Primaquine phosphate is indicated for the radical cure (prevention of relapse) of vivax malaria.

Primaquine phosphate is recommended only for the radical cure of vivax malaria, the prevention of relapse in vivax malaria, or following the termination of chloroquine phosphate suppressive therapy in an area where vivax malaria is endemic. Patients suffering from an attack of vivax malaria or having parasitized red blood cells should receive a course of chloroquine phosphate, which quickly destroys the erythrocytic parasites and terminates the paroxysm. Primaquine phosphate should be administered concurrently in order to eradicate the exoerythrocytic parasites in a dosage of 1 tablet (equivalent to 15 mg base) daily for 14 days.

Administration

Should be taken with food. Take with meals to avoid GI discomfort.

Acutely ill patients suffering from systemic disease manifested by tendency to develop granulocytopenia (e.g. rheumatoid arthritis, lupus erythematosus). Concurrent use with other potentially haemolytic drugs or depressants of myeloid elements of the bone marrow. Concomitant admin with mepacrine.

Abdominal pain, gastric distress, nausea, vomiting; methaemoglobinaemia, haemolytic anaemia (in patients with G6PD deficiency), mild anaemia, leucocytosis; HTN, cardiac arrhythmias, prolonged QT interval on ECG, accommodation disturbance. Rarely, leucopenia, agranulocytosis.

Overdose Effects

Symptoms of overdosage of Primaquine phosphate include abdominal cramps, vomiting, burning epigastric distress, central nervous system and cardiovascular disturbances, including cardiac arrhythmia and QT interval prolongation, cyanosis, methemoglobinemia, moderate leukocytosis or leukopenia, and anemia. The most striking symptoms are granulocytopenia and acute hemolytic anemia in G6PD deficient patients. Acute hemolysis occurs, but patients recover completely if the dosage is discontinued.

Patient with G6PD deficiency, NADH methaemoglobin reductase deficiency. Childn. Pregnancy and lactation.

Pregnancy & Lactation

Pregnancy Category C. Safe usage of this preparation in pregnancy has not been established. Primaquine is contraindicated in pregnant women. Even if a pregnant woman is G6PD normal, the fetus may not be. Animal data show toxicity to reproduction.

Lactation: It is not known whether Primaquine is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from Primaquine, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.