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HYDROXYCHLOROQUINE

Medical Diagnosis and Drugs, Medications
HYDROXYCHLOROQUINE
(hye-drox-ee-klor'oh-kwin)
Plaquenil Sulfate
Classifications: antimalarial;
Therapeutic: antimalarial
Prototype: Chloroquine
Pregnancy Category: C

Availability

200 mg tablets

Action

Derivative closely related to chloroquine. Antimalarial activity is believed to be based on ability to form complexes with DNA of parasite, thereby inhibiting replication and transcription to RNA and DNA synthesis of the parasite.

Therapeutic Effect

Effective against Plasmodium vivax and Plasmodium malariae.

Uses

Suppressive prophylaxis and treatment of acute malarial attacks due to all forms of susceptible malaria. Used adjunctively with primaquine for eradication of Plasmodium vivax and Plasmodium malariae. More commonly prescribed than chloroquine for treatment of rheumatoid arthritis and lupus erythematosus (usually in conjunction with salicylate or corticosteroid therapy).

Unlabeled Uses

Porphyria cutanea tarda.

Contraindications

Known hypersensitivity to, retinal or visual field changes associated with quinoline compounds; psoriasis, porphyria, G6PD deficiency; long-term therapy in children; pregnancy (category C). Safe use in juvenile arthritis is not established.

Cautious Use

Hepatic disease; alcoholism, use with hepatotoxic drugs; impaired renal function, porphoria; metabolic acidosis; patients with tendency to dermatitis.

Route & Dosage

Note: Doses are expressed in terms of hydroxychloroquine base: 400 mg tablet = 310 mg base; 800 mg tablet = 620 mg base

Acute Malaria
Adult: PO 620 mg base followed by 310 mg base at 6, 18, and 24 h
Child: PO 10 mg base/kg, then 5 mg base/kg at 6, 18, and 24 h

Malaria Suppression
Adult: PO 310 mg base the same day each week starting 2 wk before exposure and continuing for 4–6 wk after leaving the area of exposure
Child: PO 5 mg base/kg the same day each week starting 2 wk before exposure and continuing for 4–8 wk after leaving the area of exposure

Lupus Erythematosus
Adult: PO 310 mg base 1–2 times/d
Child: PO 3–5 mg/kg/d in 1–2 divided doses (max: 400 mg/d or 7 mg/kg/d)

Rheumatoid Arthritis
Adult: PO 400–600 mg/d until response, then decrease to lowest maintenance levels possible
Child: PO 3–5 mg/kg/d in 1–2 divided doses (max: 400 mg/d or 7 mg/kg/d)

Administration

Oral
  • Give drug with meals or milk to reduce incidence of GI distress.
  • Give antacids and laxatives at least 4 h before or after hydroxychloroquine.
  • Store at 15°–30° C (59°–86° F) unless otherwise directed.

Adverse Effects (≥1%)

CNS: Fatigue, vertigo, headache, mood or mental changes, anxiety, retinopathy, blurred vision, difficulty focusing. GI: Anorexia, nausea, vomiting, diarrhea, abdominal cramps, weight loss. Hematologic: Hemolysis in patients with G6PD deficiency, agranulocytosis (rare), aplastic anemia (rare), thrombocytopenia. Skin: Bleaching or loss of hair, unusual pigmentation (blue-black) of skin or inside mouth, skin rash, itching.

Interactions

Drug: Aluminum- and magnesium-containing antacids and laxatives decrease hydroxychloroquine absorption; separate administrations by at least 4 h; hydroxychloroquine may interfere with response to rabies vaccine.

Pharmacokinetics

Absorption: Rapidly and almost completely absorbed. Peak: 1–2 h. Distribution: Widely distributed; concentrates in lungs, liver, erythrocytes, eyes, skin, and kidneys; crosses placenta. Metabolism: Partially in liver to active metabolite. Elimination: In urine; excreted in breast milk. Half-Life: 70–120 h.

Nursing Implications

Assessment & Drug Effects

  • Monitor for therapeutic effectiveness; may not appear for several weeks, and maximal benefit may not occur for 6 mo.
  • Do baseline and periodic ophthalmoscopic examinations and blood cell counts on all patients on long-term therapy.
  • Discontinue drug if weakness, visual symptoms, hearing loss, unusual bleeding, bruising, or skin eruptions occur.

Patient & Family Education

  • Learn about adverse effects and their symptoms when taking prolonged therapy.
  • Follow drug regimen exactly as prescribed by the physician.
  • Make sure to keep this drug out of reach of children.

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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