primaquine (Rx)

>10%

Abdominal pain

Hemolytic anemia in G6PD deficiency

Nausea

Vomiting

<1-10%

Methemoglobinemia in NADH-methemoglobin reductase-deficient individuals

<1%

Agranulocytosis

Arrhythmias

Headache

Interference with visual accommodation

Leukopenia

Leukocytosis

Rash

Dizziness

Pruritus

Contraindications

Severe glucose-6-phosphate dehydrogenase (G6PD) deficiency

Coadministration with quinacrine in patients who have received quinacrine recently

Concurrent administration with other potentially hemolytic drugs or depressants of myeloid elements of the bone marrow

Acutely ill patients suffering from systemic disease manifested by tendency to granulocytopenia, such as rheumatoid arthritis and lupus erythematosus

Cautions

Since anemia, methemoglobinemia, and leukopenia may occur following administration of large doses of primaquine, do not exceed adult dosage of 1 tablet (= 15 mg base) daily for fourteen days; make routine blood examinations (particularly blood cell counts and hemoglobin determinations) during therapy; drug should be discontinued immediately if marked darkening of urine or sudden decrease in hemoglobin concentration or leukocyte count occurs

Observe patient for tolerance if primaquine phosphate is prescribed for an individual who has shown a previous idiosyncrasy to primaquine phosphate (as manifested by hemolytic anemia, methemoglobinemia, or leukopenia), an individual with a family or personal history of favism, or an individual with erythrocytic glucose-6-phosphate dehydrogenase (G-6-PD) deficiency or nicotinamide adenine dinucleotide (NADH) methemoglobin reductase deficiency; discontinue therapy immediately if marked darkening of the urine or sudden decrease in hemoglobin concentration or leukocyte count occurs

Due to potential for QT interval prolongation, monitor ECG when using primaquine in patients with cardiac disease, long QT syndrome, a history of ventricular arrhythmias, uncorrected hypokalemia and/or hypomagnesemia, or bradycardia (<50 bpm), and during concomitant administration with QT interval prolonging agents

Pregnancy

Contraindicated in pregnant women; even if a pregnant woman is G6PD normal, the fetus may not be; safe usage in pregnancy not established; use during pregnancy should be avoided except when in judgment of the physician benefit outweighs possible hazard

Sexually-active females of reproductive potential should have a pregnancy test prior to starting primaquine

Contraception

• Advise females of child bearing potential to use effective contraception (methods that result in less than 1% pregnancy rates) when receiving therapy and after stopping treatment until completion of an ongoing ovulatory cycle (eg, up to next menses)
• Advise treated males whose partners may become pregnant, to use a condom while on treatment and for 3 months after stopping treatment

Lactation

CDC recommends do not use in nursing women unless breast-fed infant has been determined not to have G6PD deficiency

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

Mechanism of Action

Disrupts Plasmodium mitochondria

Absorption

Absorption: Well absorbed

Peak Plasma Time: 1-2 hr

Metabolism

Metabolism: Hepatic to carboxyprimaquine (active)

Elimination

Half-life: 3.7-9.6 hr

Excretion: Urine (small amounts as unchanged drug)

Oral administration

Take without meals

If patient vomits within 30 minutes of taking a dose, then should repeat dose

Storage

Store at 25°C (77° F); excursions permitted to 15-30° C (59-86° F)

Dispense in tight, light-resistant container