Hydroxychloroquine and chloroquine

Author: Dr Amanda Oakley, Dermatologist, Waikato Hospital, Hamilton, New Zealand, 2001.

Hydroxychloroquine and chloroquine are anti-malarial medications. Besides being active against malaria, they are used to treat rheumatoid arthritis and cutaneous lupus erythematosus (LE) and rashes associated with systemic lupus erythematosus (SLE). They are also used in some photosensitivity disorders and occasionally in other inflammatory skin conditions. Hydroxychloroquine is used much more frequently than chloroquine, as chloroquine is more likely to cause permanent damage to eyesight.

Hydroxychloroquine is available in New Zealand as Plaquenil®, in 200 mg tablets. The usual dose for skin disease is 200 to 600 mg daily, best taken after meals.

Supply of chloroquine in New Zealand has been discontinued.

Drug interactions with antimalarials

Hydroxychloroquine may interfere with:

Chloroquine may interfere with:

Contraindications to antimalarials

Antimalarial medications may be unsuitable in the following circumstances:

Doses of hydroxychloroquine may need to be lower in those who have liver or kidney disease.

Hydroxychloroquine and chloroquine are classified as Category D in pregnancy. They should only be taken during pregnancy if essential.

Adverse effects of antimalarials

Adverse effects of antimalarials are uncommon. They include:

Antimalarials may aggravate psoriasis.

Antimalarials are highly toxic if taken in overdose, especially to the heart.

Visual effects of antimalarials

Visual toxicity due to antimalarials affects the retina. This may occur after chloroquine has been taken for a year or longer, or if the total dose is more than 1.6 g/kg bodyweight. Visual toxicity may also occur after hydroxychloroquine has been taken for several years (generally over 8 years continuous treatment). Unfortunately, decreased vision may be permanent. To decrease the chance of this occurring:

For patients taking hydroxychloroquine in New Zealand, most ophthalmologists recommend routine eye checks as a baseline if there is any visual impairment not corrected by glasses. Those without visual symptoms or visual impairment should be seen by an ophthalmologist for a full assessment after 5 years or so (earlier if there are symptoms). These checks are likely to include visual acuity, Ishihara colour test, examination of the back of the eye (fundus) and central visual field examination. Worrying features on examination include pigmentation (dark coloration) or loss of pigmentation of the retina, optic atrophy (damaged nerve) and scotoma (tunnel vision). An electroretinogram (ERG) may be performed if any screening tests are abnormal.

Place the grid on a flat surface and hold it at a distance of 33 cm. While looking at the dot in the centre of the grid, observe the rest of the lines. All the borders should be visible and all the lines straight. If not, retest after a few hours.

Hold the grid at arms length; focus on the black dot in the centre, first with one eye then the other. If the lines are altered or missing or you are having difficulty focussing, stop hydroxychloroquine and notify your doctor.

Laboratory monitoring

Periodic blood counts are recommended as antimalarial medications can rarely result in dangerous reduction in cell counts.

It is also wise to check renal and liver function before treatment and from time to time.

Related information

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