It has been found that certain strains of P.
falciparum have become resistant to 4-aminoquinoline compounds (including
chloroquine and hydroxychloroquine). Chloroquine resistance is widespread and,
at present, is particularly prominent in various parts of the world including
sub-Saharan Africa, Southeast Asia, the Indian subcontinent, and over large
portions of South America, including the Amazon basin1.
Before using chloroquine for prophylaxis, it should be
ascertained whether chloroquine is appropriate for use in the region to be
visited by the traveler. Chloroquine should not be used for treatment of P.
falciparum infections acquired in areas of chloroquine resistance or
malaria occurring in patients where chloroquine prophylaxis has failed.
Patients infected with a resistant strain of plasmodia as
shown by the fact that normally adequate doses have failed to prevent or cure
clinical malaria or parasitemia should be treated with another form of
Retinopathy/maculopathy, as well as macular degeneration
have been reported (see ADVERSE REACTIONS), and 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. Risk factors for the development of retinopathy include age, duration
of treatment, high daily and/or cumulated doses.
When prolonged therapy with any antimalarial compound is
contemplated, initial (base line) and periodic ophthalmologic examinations
(including visual acuity, expert slit-lamp, funduscopic, and visual field
tests) should be performed.
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.
Acute extrapyramidal disorders may occur with chloroquine
(see ADVERSE REACTIONS and OVERDOSAGE). These adverse reactions
usually resolve after treatment discontinuation and/or symptomatic treatment.
All patients on long-term therapy with this preparation
should be questioned and examined periodically, including testing knee and
ankle reflexes, to detect any evidence of muscular weakness. If weakness
occurs, discontinue the drug.
A number of fatalities have been reported following the
accidental ingestion of chloroquine, sometimes in relatively small doses (0.75
g or 1 g chloroquine phosphate in one 3-year-old child). Patients should be
strongly warned to keep this drug out of the reach of children because they are
especially sensitive to the 4-aminoquinoline compounds.
Use of ARALEN in patients with psoriasis may precipitate
a severe attack of psoriasis. When used in patients with porphyria the
condition may be exacerbated. The drug should not be used in these conditions
unless in the judgment of the physician the benefit to the patient outweighs
the potential risks.
Usage in Pregnancy
Radioactively tagged chloroquine administered
intravenously to pregnant pigmented CBA mice passed rapidly across the placenta
and accumulated selectively in the melanin structures of the fetal eyes. It was
retained in the ocular tissues for five months after the drug had been
eliminated from the rest of the body2. There are no adequate and
well-controlled studies evaluating the safety and efficacy of chloroquine in
pregnant women. Usage of chloroquine during pregnancy should be avoided except
in the suppression or treatment of malaria when in the judgment of the
physician the benefit outweighs the potential risk to the fetus.
1. Malaria Deaths Following Inappropriate Malaria
Chemoprophylaxis – United States, 2001. MMWR Weekly, 2001; 50(28): 597-599.
2. Ullberg S, Lindquist N G, Sjostrand S E: Accumulation
of chorioretinotoxic drugs in the foetal eye. Nature 1970; 227: 1257.