Chloroquine

Pronunciation

Pronunciation: KLOR-oh-kwin
Class: 4-aminoquinoline compound, Amebicide

Trade Names

Aralen Phosphate
- Tablets 500 mg chloroquine phosphate (equivalent to 300 mg base)

Aralen (Canada)

Pharmacology

Inhibits parasite growth, possibly by concentrating within parasite acid vesicles, raising pH.

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Pharmacokinetics

Absorption

Rapidly and almost completely absorbed from the GI tract.

Distribution

About 55% bound to nondiffusable plasma constituents. Distributed considerably into tissues (ie, liver, spleen, kidney, lung) and to a lesser extent into brain and spinal cord.

Metabolism

The main metabolite is desethylchloroquine.

Elimination

Slowly excreted, but increased by acidification of the urine. A small amount is excreted in the feces. About 25% of the dose is excreted in urine as desethylchloroquine. More than 50% of urinary drug product is unchanged chloroquine.

Indications and Usage

Prophylaxis and treatment of acute attacks of malaria caused by Plasmodium vivax , Plasmodium malariae , Plasmodium ovale , and susceptible strains of Plasmodium falciparum ; extraintestinal amebiasis.

Unlabeled Uses

Treatment of rheumatoid arthritis, systemic and discoid lupus erythematosus, porphyria cutanea tarda, scleroderma, pemphigus, lichen planus, polymyositis, and sarcoidosis.

Contraindications

Retinal or visual field changes.

Dosage and Administration

Doses are listed in base equivalents.

Acute Malaria
Adults

PO Initial dose is 600 mg, then 300 mg 6 h later and 300 mg every day for 2 days.

Children

PO Initial dose is 10 mg/kg, then 5 mg/kg 6 h later and 5 mg/kg every day for 2 days.

Malaria Suppression
Adults

PO 300 mg base.

Children

5 mg/kg/dose (max 300 mg base) weekly. Begin 1 to 2 wk prior to exposure and continue for 4 wk after leaving endemic area. If suppressive therapy is not begun prior to exposure, double initial loading dose and give in 2 divided doses 6 h apart.

Extraintestinal Amebiasis
Adults

PO 600 mg base/day for 2 days, then 300 mg base/day for 2 to 3 wk.

General Advice

  • Administer with food or milk.
  • If taken once weekly, take on same day of week.

Storage/Stability

Store in airtight, light-resistant container at room temperature.

Drug Interactions

Cimetidine

May increase chloroquine serum concentration.

Kaolin aluminum or magnesium trisilicate antacids

May decrease GI absorption of chloroquine.

Rabies vaccine

Coadministration of intradermally administered rabies vaccine and chloroquine may result in diminished antibody response to vaccine. In this situation CDC recommends administering rabies vaccine IM.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Hypotension; ECG changes.

CNS

Headache; neuropathy; seizures; psychotic episodes.

Dermatologic

Pruritus; pigment changes; skin eruptions.

EENT

Visual disturbances; retinal damage and deafness with prolonged high-dose use; tinnitus.

GI

Anorexia; nausea; vomiting; diarrhea; abdominal cramps.

Hematologic

Agranulocytosis; blood dyscrasias; aplastic anemia.

Hepatic

Hepatitis.

Miscellaneous

Muscle weakness.

Precautions

Monitor

Neuromuscular exam

Perform periodic neuromuscular examinations and notify patient if knee and ankle reflexes are weak.

Adverse reactions

If sore throat, fever, weakness, fatigue, or unusual bleeding or bruising occurs, notify health care provider.


Pregnancy

Category D .

Lactation

Excreted in breast milk.

Children

Especially sensitive to adverse reactions; do not exceed recommended dose.

Special Risk Patients

Monitor patients with hepatic disease or alcoholism, or taking other hepatotoxic medications for evidence of worsening liver function such as bleeding.

G-6-PD deficiency

May induce hemolysis in presence of infection or stressful condition.

Muscular weakness

May need to discontinue therapy if muscle weakness occurs.

Psoriasis or porphyria

May be exacerbated.

Retinopathy

Irreversible retinal damage has occurred.

Overdosage

Symptoms

Headache, drowsiness, visual disturbances, CV collapse, seizures, respiratory and cardiac arrest, death.

Patient Information

  • Remind patient to take medication with food to minimize GI irritation.
  • Stress importance of compliance with full course of therapy. If used for suppression, drug must be taken at least 1 wk before entering and for 4 wk after leaving endemic area.
  • Caution patient to drink alcoholic beverages sparingly because of increased GI irritation and higher risk of liver damage.
  • Stress importance of eye examinations every 3 to 6 mo during prolonged daily therapy.
  • Inform patient that drug may cause rusty or brown discoloration of urine.
  • Advise use of dark glasses in bright light to reduce risk of ocular damage.
  • Instruct patient to report these symptoms to health care provider: blurring or change in vision, buzzing or difficulty hearing, muscle weakness, rash, vomiting or stomach pain, difficulty breathing or swallowing.

Copyright © 2009 Wolters Kluwer Health.

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