Chloroquine hydrochloride
Chloroquine hydrochloride (Aralen)
Chloroquine
( KLOR-oh-kwin) Aralen HCl (Rx)
Chloroquine phosphate
Chloroquine phosphate (Aralen Phosphate)
Chloroquine
( KLOR-oh-kwin) Aralen Phosphate Novo-Chloroquine (Rx)

Classification: 4-Aminoquinoline, antimalarial, amebicide

Action/Kinetics: Several mechanisms have been proposed for the action of 4-aminoquinolines. These include (a) an active chloroquine-concentrating mechanism in the acid vesicles of the parasite causing inhibition of growth, (b) release of aggregates of ferriprotoporphyrin IX from erythrocytes in the parasite causing membrane damage and erythrocyte or parasite lysis, (c) interference with hemoglobin digestion by the parasite, and (d) interference with synthesis of nucleoprotein by the parasite. 4-Aminoquinolines are active against the erythrocytic forms of Plasmodium vivax and P. malariae as well as most strains of P. falciparum. They are rapidly and almost completely absorbed from the GI tract and are widely distributed throughout the body. Peak serum levels: 1-6 hr. Very slowly excreted; presence of drug has been demonstrated in the bloodstream weeks and even months after the drug has been discontinued. Up to 70% may be excreted unchanged. Urinary excretion is increased by acidifying the urine; excretion is slowed by alkalinization.

Uses: Treatment or prophylaxis of acute attacks of malaria caused by Plasmodium falciparum, P. vivax, P. ovale and P. malariae. Will cause a radical cure of vivax and malariae malaria if combined with primaquine. Effective only against the erythrocytic stages and therefore will not prevent infections. However, complete cure of infections due to sensitive strains of falciparum malaria is possible.
Extraintestinal amebiasis caused by Entamoeba histolytica. Discoid or lupus erythematosus, scleroderma, pemphigus, lichen planus, polymyositis, sarcoidosis, porphyria cutanea tarda.

Contraindications: Hypersensitivity. Changes in retinal or visual field. Lactation. Use in psoriasis or porphyria only if benefits clearly outweigh risks. Concomitantly with gold or in clients receiving drugs that depress blood-forming elements of bone marrow.

Special Concerns: Use during pregnancy only if benefits outweigh risks. Use with extreme caution in the presence of hepatic, severe GI, neurologic, and blood disorders. Infants and children are sensitive to the effects of 4-aminoquinolines. Certain strains of P. falciparum are resistant to 4-aminoquinolines.

Side Effects: GI: N&V;, diarrhea, cramps, anorexia, epigastric distress, stomatitis, dry mouth. CNS: Headache, fatigue, nervousness, anxiety, irritability, agitation, apathy, confusion, personality changes, depression, psychoses, seizures. CV: Hypotension, ECG changes (inversion or depression of T wave, widening of QRS complex). Dermatologic: Pruritus, changes in pigment of skin and mucous membranes, dermatoses, bleaching of hair. Hematologic: Neutropenia, aplastic anemia thrombocytopenia, agranulocytosis. Ocular: Retinopathy that may be permanent and may lead to blindness. Blurred vision, difficulty in focusing or in accommodation; chronic use may lead to corneal deposits or keratopathy. Miscellaneous: Peripheral neuritis, ototoxicity, neuromyopathy manifested by muscle weakness, worsening of psoriasis (may preceipitate an acute attack).

Laboratory Test Alterations: Colors urine brown.

Overdose Management: Symptoms: Headache, drowsiness, visual disturbances, CV collapse, seizures followed by sudden and early respiratory and cardiac arrest. Infants and children have manifested respiratory depression, CV collapse, shock, seizures, and death following overdoses of parenteral chloroquine. ECG changes include nodal rhythm, atrial standstill, prolonged intraventricular conduction, and bradycardia, which lead to ventricular fibrillation or arrest. Treatment: Undertake gastric lavage or emesis followed by activated charcoal. Seizures should be controlled prior to gastric lavage. Seizures due to anoxia can be treated by oxygen, mechanical ventilation, or vasopressors (in shock with hypotension). Tracheostomy or tracheal intubation may be required. Forced fluids and acidification of the urine may hasten excretion. Peritoneal dialysis and exchange transfusions may also help.

Drug Interactions: Acidifying agents, urinary (ammonium chloride, etc.) / Urinary excretion of chloroquine effect Alkalinizing agents, urinary (bicarbonate, etc.) / Excretion of chloroquine level of drug in body Antipsoriatics / 4-Aminoquinolines inhibit antipsoriatic drugs Cimetidine / Oral clearance rate and metabolism of chloroquine Kaolin / Effect of chloroquine due to GI absorption Magnesium trisilicate / Effect of chloroquine due to GI absorption MAO inhibitors / Toxicity of 4-aminoquinolines due to liver breakdown

How Supplied: Chloroquine hydrochloride: Injection: 50 mg/mL Chloroquine phosphate: Tablet: 250 mg, 500 mg

Dosage
Chloroquine Hydrohloride ?IM Acute malarial attack.
Adults, initial: 200-250 mg (160-200 mg base); repeat dosage in 6 hr if necessary. Total daily dose in first 24 hr should not exceed 1 g (800 mg base). Begin PO therapy as soon as possible. IM, SC. Children and infants: 6.25 mg/kg (5 mg base/kg) repeated in 6 hr; dose should not exceed 12.5 mg/kg/day (10 mg base/kg/day).
Extraintestinal amebiasis.
Adults: 200-250 mg/day (160-200 mg of the base) for 10-12 days. Begin PO therapy as soon as possible. Children: 7.5 mg/kg/day for 10-12 days.
?IV Infusion Acute malarial attack.
Adults, initial: 16.6 mg/kg over 8 hr; then, 8.3 mg/kg q 6-8 hr by continuous infusion.
Chloroquine Phosphate ?Tablets Acute malarial attack.
Adults, Day 1: 1 g (600 mg base); then, 500 mg (300 mg base) 6 hr later. Days 2 and 3: 500 mg/day (300 mg base/day). Children, Day 1: 10 mg base/kg; then 5 mg base/kg 6 hr later. Days 2 and 3: 5 mg base/kg/day.
Suppression (prophylaxis) of malaria.
Adults: 500 mg/week (300 mg base/week) on same day each week. If therapy has not been initiated 14 days before exposure, an initial loading dose of 1 g (600 mg base) may be given in 500-mg doses 6 hr apart. Children: 5 mg base/kg/week, not to exceed the adult dose of 300 mg of the base, given on same day each week. If therapy has not been initiated 14 days before exposure, an initial loading dose of 10 mg/kg of the base may be given in two divided doses 6 hr apart.
Extraintestinal amebiasis.
Adults: 1 g (600 mg base) given as 250 mg q.i.d. for 2 days; then, 500 mg (300 mg base) given as 250 mg b.i.d. for 2-3 weeks (combine with an intestinal amebicide). Children: 10 mg/kg (not to exceed 500 mg) daily for 3 weeks.