Home Drug Guide Primaquine Phosphate

Drug Guide

Generic Name

Primaquine Phosphate

Brand Names Primaquine

Classification

Therapeutic: Antimalarial

Pharmacological: 2-Aminopyridine derivative

FDA Approved Indications

Prevention and treatment of relapse of Plasmodium vivax and Plasmodium ovale malaria

Mechanism of Action

Primaquine acts by producing oxidative stress within the parasite, damaging their mitochondria and other cellular components, leading to parasite death. It is effective against the liver (hypnozoite) stages of certain Plasmodium species.

Dosage and Administration

Adult: Usually 15 mg base (26.3 mg phosphate) once daily for 14 days.

Pediatric: Dose based on weight, typically 0.5 mg/kg/day for 14 days.

Geriatric: Adjusted dose depending on renal and hepatic function; caution advised.

Renal Impairment: Use with caution; monitor renal function and consider dosage adjustments.

Hepatic Impairment: Caution recommended; hepatic function should be monitored.

Pharmacokinetics

Absorption: Well absorbed orally.

Distribution: Widely distributed in body tissues, including liver.

Metabolism: Primarily hepatic via CYP2D6 enzymes.

Excretion: Metabolites excreted in urine.

Half Life: Approximately 4-7 hours.

Contraindications

G6PD deficiency (risk of hemolysis)
Allergy to primaquine

Precautions

Use in pregnancy only if benefits outweigh risk, as data is limited.
Monitor for hemolytic anemia, especially in G6PD deficiency.

Adverse Reactions - Common

Gastrointestinal upset (nausea, vomiting) (Common)
Headache (Common)

Adverse Reactions - Serious

Hemolytic anemia (in G6PD deficiency) (Serious, risk increases in G6PD deficiency)
Leukopenia, thrombocytopenia (Serious, rare)

Drug-Drug Interactions

Be cautious with other drugs causing hemolysis or bone marrow suppression, e.g., sulfonamides.

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Assess G6PD status before initiation. Monitor hemoglobin, hematocrit, and liver function tests.

Diagnoses:

Risk for hemolytic anemia
Risk for hepatic injury

Implementation: Administer with food to reduce gastrointestinal upset. Educate patient on importance of adherence to the full course.

Evaluation: Monitor for signs of hemolysis, adverse reactions, and effectiveness of treatment.

Patient/Family Teaching

Instruct to complete the full course of therapy.
Advise to report any symptoms of anemia (fatigue, weakness, pallor).
Warn against use without G6PD testing.
Discuss the importance of regular blood tests during therapy.

Special Considerations

Black Box Warnings:

Hemolytic anemia in patients with G6PD deficiency.

Genetic Factors: CYP2D6 poor metabolizers may have reduced efficacy.

Lab Test Interference: May interfere with some liver function tests.

Overdose Management

Signs/Symptoms: Hemolytic anemia, gastrointestinal symptoms, dizziness.

Treatment: Supportive care, blood transfusions if necessary, monitor hemoglobin levels, and ensure adequate hydration.

Storage and Handling

Storage: Store at room temperature, away from moisture and direct light.

Stability: Stable under recommended conditions until expiration date.