For Malaria and
Extraintestinal Amebiasis


Parenteral solution, each mL containing 50 mg of the dihydrochloride salt equivalent to 40 mg of chloroquine base. Chloroquine hydrochloride, a 4-aminoquinoline compound, is chemically 7- (Chloro - 4 - [ [ 4 - diethylamino) - 1 - methylbutyl] amino]-quinoline dihydrochloride, a white, crystalline substance, freely soluble in water.


The compound is a highly active antimalarial and amebicidal agent.

ARALEN has been found to be highly active against the erythrocytic forms of Plasmodium vivax and malariae and most strains of Plasmodium falciparum (but not the gametocytes of P. falciparum). The precise mechanism of action of the drug is not known.

ARALEN does not prevent relapses in patients with vivax or malariae malaria because it is not effective against exoerythrocytic forms of the parasite, nor will it prevent vivax or malariae infection when administered as a prophylactic. It is highly effective as a suppressive agent in patients with vivax or malariae malaria, in terminating acute attacks, and significantly lengthening the interval between treatment and relapse. In patients with falciparum malaria it abolishes the acute attack and effects complete cure of the infection, unless due to a resistant strain of P. falciparum.


ARALEN is indicated for the treatment of extraintestinal amebiasis and for treatment of acute attacks of malaria due to P. vivax, P. malariae, P. ovale, and susceptible strains of P. falciparum when oral therapy is not feasible.


Use of this drug is contraindicated in the presence of retinal or visual field changes either attributable to 4- aminoquinoline compounds or to any other etiology, and in patients with known hypersensitivity to 4-aminoquinoline compounds. However, in the treatment of acute attacks of malaria caused by susceptible strains of plasmodia, the physician may elect to use this drug after carefully weighing the possible benefits and risks to the patient.

Children and infants are extremely susceptible to adverse effects from an overdose of parenteral ARALEN and sudden deaths have been recorded after such administration. In no instance should the single dose of parenteral ARALEN administered to infants or children exceed 5 mg base per kg.

In recent years it has been found that certain strains of P. falciparum have become resistant to 4-aminoquinoline compounds (including chloroquine and hydroxychloroquine) as shown by the fact that normally adequate doses have failed to prevent or cure clinical malaria or parasitemia. Treatment with quinine or other specific forms of therapy is therefore advised for patients infected with a resistant strain of parasites.

Use of ARALEN should be avoided in patients with psoriasis, for it may precipitate a severe attack of psoriasis. Some authors consider the use of 4-aminoquinoline compounds contraindicated in patients with porphyria since the condition may be exacerbated.

Irreversible retinal damage has been observed in some patients who had received long-term or high-dosage 4-aminoquinoline therapy. Retinopathy has been reported to be dose related.

If there is any indication (past or present) of abnormality in the visual acuity, visual field, or retinal macular areas (such as pigmentary changes, loss of foveal reflex), or any visual symptoms (such as light flashes and streaks) which are not fully explainable by difficulties of accommodation or corneal opacities, the drug should be discontinued immediately and the patient closely observed for possible progression. Retinal changes (and visual disturbances) may progress even after cessation of therapy.

Usage in Pregnancy. Usage of this drug during pregnancy should be avoided except in the suppression or treatment of malaria when in the judgment of the physician the benefit outweighs the possible hazard. It should be noted that radioactively tagged chloroquine administered intravenously to pregnant pigmented CBA mice passed rapidly across the placenta, accumulated selectively in the melanin structures of the fetal eyes and was retained in the ocular tissues for five months after the drug had been eliminated from the rest of the body. 1


Since the drug is known to concentrate in the liver, it should be used with caution in patients with hepatic disease or alcoholism or in conjunction with known hepatotoxic drugs.

The drug should be administered with caution to patients having G-6-PD (glucose-6-phosphate dehydrogenase) deficiency.


Respiratory depression, cardiovascular collapse, shock, convulsions, and death have been reported with overdoses of ARALEN, brand of chloroquine hydrochloride injection, especially in infants and children.

Any of the adverse reactions associated with short-term oral administration of chloroquine phosphate must be considered a possibility with chloroquine hydrochloride. Cardiovascular effects, such as hypotension and electrocardiographic changes (particularly inversion or depression of the T-wave, widening of the QRS complex), have rarely been noted in patients receiving usual antimalarial doses of the drug. Mild and transient headache, pruritus, psychic stimulation, visual disturbances (blurring of vision and difficulty of focusing or accommodation), pleomorphic skin eruptions, and gastrointestinal complaints (anorexia, nausea, vomiting, diarrhea, abdominal cramps) have been observed.

Instances of convulsive seizures associated with oral chloroquine therapy in patients with extraintestinal amebiasis have been reported.

A few cases of a nerve type of deafness have been reported after prolonged therapy, usually in high doses. Tinnitus and reduced hearing have been reported, in a patient with preexistent auditory damage, after administration of only 500 mg once a week for a few months. Since neuromyopathy, blood dyscrasias, lichen planus-like eruptions, and skin and mucosal pigmentary changes have been noted during prolonged oral therapy, their occurrence with this dosage form is possible.

Patients with retinal changes may be asymptomatic, especially in early cases, or may complain of nyctalopia and scotomatous vision with field defects of paracentral, pericentral ring types, and typically temporal scotomas, eg, difficulty in reading with words tending to disappear, seeing only half an object, misty vision, and fog before the eyes. Rarely scotomatous vision may occur without observable retinal changes.


Malaria -- Adult Dose. An initial dose of 4 mL or 5 mL (160 mg to 200 mg chloroquine base) may be injected intramuscularly and repeated in 6 hours if necessary. The total parenteral dosage in the first 24 hours should not exceed 800 mg chloroquine base. Treatment by mouth should be started as soon as practicable and continued until a course of approximately 1.5 g of base in 3 days is completed.

Pediatric Dose. Infants and children are extremely susceptible to overdosage of parenteral ARALEN. Severe reactions and deaths have occurred. In the pediatric age range, parenteral ARALEN dosage should be calculated in proportion to the adult dose based upon body weight. The recommended single dose in infants and children is 5 mg base per kg. This dose may be repeated in 6 hours; however, the total dose in any 24 hour period should not exceed 10 mg base per kg of body weight. Parenteral administration should be terminated and oral therapy instituted as soon as possible.

Extraintestinal Amebiasis -- In adult patients not able to tolerate oral therapy, from 4 mL to 5 mL (160 mg to 200 mg chloroquine base) may be injected daily for 10 to 12 days. Oral administration should be substituted or resumed as soon as possible.


Inadvertent toxic doses may produce respiratory depression or shock with hypotension. Respiratory depression is treated by artificial respiration and administration of oxygen. In shock with hypotension, a potent vasopressor, such as NEO-SYNEPHRINE® hydrochloride, brand of phenylephrine hydrochloride, USP, should be given intramuscularly in doses of 2 mg to 5 mg.


Ampuls of 5 mL (250 mg/5 mL), box of 5 (NDC 0024-0074-01)

Store at room temperature up to 30°C (86°F).


Ullberg S, Lindquist N G, Sjostrand S E: Accumulation of chorio-retinotoxic drugs in the foetal eye. Nature 1970; 227:1257.                     Revised September 1999