Action And Clinical Pharmacology: Primaquine is an 8-aminoquinoline compound which eliminates tissue (exo-erythrocytic) infection. Thereby, it prevents the development of the erythrocytic forms of the parasite which are responsible for relapses in vivax and ovale malaria. Primaquine phosphate is also active against gametocytes of P. falciparum.
Indications And Clinical Uses: For the radical cure (prevention of relapse) of vivax and ovale malaria.
Contra-Indications: In acutely ill patients suffering from systemic disease manifested by tendency to granulocytopenia, such as rheumatoid arthritis and lupus erythematosus. In patients receiving concurrently other potentially hemolytic drugs or depressants of myeloid elements of the bone marrow.
Quinacrine appears to potentiate the toxicity of antimalarial compounds which are structurally related to primaquine; therefore, the use of quinacrine in patients receiving primaquine is contraindicated. Similarly, primaquine should not be administered to patients who have received quinacrine recently, as toxicity is increased.
Manufacturers’ Warnings In Clinical States: Discontinue the use of primaquine promptly if signs suggestive of hemolytic anemia occur such as darkening of urine, marked fall of hemoglobin or erythrocyte count.
Hemolytic reactions (moderate to severe) may occur in glucose-6-phosphate dehydrogenase (G-6-PD) deficient Caucasians, particularly in Sardinians and in individuals with a family or personal history of favism. Dark skinned persons have a great tendency to develop hemolytic anemia (due to congenital deficiency of erythrocytic G-6-PD) while receiving primaquine and related drugs.
Pregnancy: Safe usage of this preparation in pregnancy has not been established. Therefore, use of it during pregnancy should be avoided except when in the judgment of the physician the benefit outweighs the possible hazard.
Precautions: Anemia, methemoglobinemia, and leukopenia have been observed following administration of large doses of primaquine; therefore, the adult dosage of 1 tablet daily for 14 days should not be exceeded. It is also advisable to make routine blood examinations, particularly blood cell counts and hemoglobin determinations, during therapy.
If primaquine is prescribed for a patient who has shown a previous idiosyncrasy to primaquine (as manifested by hemolytic anemia, methemoglobinemia, or leukopenia) or who has a family or personal history of favism, or G-6-PD deficiency or nicotinamide adenine dinucleotide (NADH) methemoglobin reductase deficiency, the patient should be observed closely for tolerance.
Discontinue drug immediately if marked darkening of urine, or sudden decrease in hemoglobin concentration or leukocyte count occurs.
Adverse Reactions: Gastrointestinal: Nausea, vomiting, epigastric distress, and abdominal cramps.
Hematologic: Leukopenia, hemolytic anemia in G-6-PD deficient individuals, and methemoglobinemia in NADH methemoglobin reductase deficient individuals.
Symptoms And Treatment Of Overdose: Symptoms: Abdominal cramps, vomiting, burning epigastric distress, CNS and cardiovascular disturbances, cyanosis, methemoglobinemia, moderate leukocytosis or leukopenia, and anemia. The most striking symptoms are granulocytopenia and acute hemolytic anemia in sensitive persons. Acute hemolysis occurs, but patients recover completely if the dosage is discontinued.
Treatment: Empty the stomach by emesis or aspiration and lavage. Assist respiration and administer i.v. fluids and vasopressors for hypotension. Ammonium chloride in doses up to 12 g daily orally may be given to enhance urinary excretion. Sodium lactate i.v. may be used to counter the depressant effects of primaquine on the heart. Electrical pacing of the heart may be needed.
Dosage And Administration: Primaquine phosphate is recommended only for the radical cure of vivax and ovale malaria, the prevention of relapse in vivax and ovale malaria, or following the termination of chloroquine phosphate suppressive therapy in an area where vivax or ovale malaria is endemic. Patients suffering from an attack of vivax or ovale 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 should be administered concurrently in order to eradicate the exo-erythrocytic parasites in an adult dosage of 1 tablet (equivalent to 15 mg base) daily for 14 days.
When primaquine is indicated for the prevention of delayed primary attacks and relapse of P. ovale or P. vivax malaria in individuals who have returned home from areas where these plasmodial species are endemic, primaquine is generally initiated during the last 2 weeks of, or immediately following, therapy with chloroquine or another suitable antimalarial agent.
Availability And Storage: Each pink, film-coated tablet, imprinted W on one side and P97 on the other, contains: primaquine phosphate USP 26.3 mg (equivalent to primaquine base 15 mg). Nonmedicinal ingredients: cellulose (microcrystalline), hydroxypropylmethylcellulose, lactose, magnesium stearate, polyethylene glycol 400, polysorbate 80, red iron oxide, starch, talc and titanium dioxide. Gluten- and tartrazine-free. Bottles of 100.
PRIMAQUINE Sanofi Primaquine Phosphate Antimalarial