PRIMAQUINE PHOSPHATE

PRIMAQUINE PHOSPHATE
(prim'a-kween)
Primaquine
Classifications: antimalarial;
Therapeutic: antimalarial

Prototype: Chloroquine
Pregnancy Category: C

Availability

26.3 mg tablets; 5 g, 25 g, 100 g, 500 g powder

Action

Acts on primary exoerythrocytic forms of Plasmodium vivax and Plasmodium falciparum by an incompletely known mechanism. Destroys late tissue forms of P. vivax and thus effects radical cure (prevents relapse).

Therapeutic Effect

Gametocidal activity against all species of Plasmodia that infect humans; interrupts transmission of malaria.

Uses

To prevent relapse ("radical" or "clinical" cure) of P. vivax and P. ovale malarias and to prevent attacks after departure from areas where P. vivax and P. ovale malarias are endemic. With clindamycin for the treatment of Pneumocystis carinii pneumonia (PCP) in AIDS.

Contraindications

Hypersensitivity to primaquine or iodoquinol; rheumatoid arthritis; lupus erythematosus (SLE); hemolytic drugs, concomitant or recent use of agents capable of bone marrow depression (e.g., quinacrine; patients with G6PD deficiency); pregnancy (category C), lactation.

Cautious Use

Bone marrow depression; hematologic disease; methemoglobin reductase deficiency.

Route & Dosage

Malaria Treatment
Adult: PO 30 mg daily for 14 d concomitantly or consecutively with chloroquine or hydroxychloroquine on first 3 d of acute attack
Child: PO 0.5 mg/kg daily for 14 d concomitantly or consecutively with chloroquine or hydroxychloroquine on first 3 d of acute attack

Malaria Prophylaxis
Adult: PO 15 mg daily for 14 d beginning immediately after leaving malarious area
Child: PO 0.3 mg/kg daily for 14 d beginning immediately after leaving malarious area

Administration

Oral
  • Give drug at mealtime or with an antacid (prescribed); may prevent or relieve gastric irritation. Notify physician if GI symptoms persist.
  • Store in tight, light-resistant containers.

Adverse Effects (≥1%)

Hematologic: Hematologic reactions including granulocytopenia and acute hemolytic anemia in patients with G6PD deficiency, moderate leukocytosis or leukopenia, anemia, granulocytopenia, agranulocytosis. GI: Nausea, vomiting, epigastric distress, abdominal cramps. Skin: Pruritus. Metabolic: Methemoglobinemia (cyanosis). Body as a Whole: Headache, confusion, mental depression. Special Senses: Disturbances of visual accommodation. CV: Hypertension, arrhythmias (rare).

Interactions

Drug: Toxicity of both quinacrine and primaquine increased.

Pharmacokinetics

Absorption: Readily from GI tract. Peak: 6 h. Metabolism: Rapidly in liver to active metabolites. Elimination: In urine. Half-Life: 3.7–9.6 h.

Nursing Implications

Assessment & Drug Effects

  • Be aware drug may precipitate acute hemolytic anemia in patients with G6PD deficiency, an inherited error of metabolism carried on the X chromosome, present in about 10% of American black males and certain white ethnic groups: Sardinians, Sephardic Jews, Greeks, and Iranians. Whites manifest more intense expression of hemolytic reaction than do blacks. Screen for prior to initiation of therapy.
  • Lab tests: Perform repeated hematologic studies (particularly blood cell counts and Hgb) and urinalyses during therapy.

Patient & Family Education

  • Examine urine after each voiding and to report to physician darkening of urine, red-tinged urine, and decrease in urine volume. Also report chills, fever, precordial pain, cyanosis (all suggest a hemolytic reaction). Sudden reductions in hemoglobin or erythrocyte count suggest an impending hemolytic reaction.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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