Hydroxychloroquine (Plaquenil)

DRUGS WITH OCULAR SIDE EFFECTS OF RECENT CLINICAL IMPORTANCE

HYDROXYCHLOROQUINE (PLAQUENIL^®)

Primary Use

Hydroxychloroquine is used primarily for the treat-ment of rheumatoid arthritis and lupus erythematosus, dermatologic conditions and various other inflamma-tory disorders.

Clinical Concerns

Definition of Hydroxychloroquine Maculopathy

Maculopathy must be bilateral and reproducible by Amsler grid and visual field testing. Transient or unilateral defects are not sufficient to implicate the drug or are they an indication to stop therapy.

Goal of Ocular Evaluation

The goal is to find early changes, i.e. relative scotomas. Later findings include retinal changes, color vision loss, absolute scotoma or decreased vision, as even if the drug is stopped, two-thirds of these patients may continue to lose some vision and/or peripheral fields. Disease in patients with early paracentral rela-tive scotomas seldom advances when the drug is discontinued.

Guidelines for Following Patients (Modified After Easterbrook, 1999)

·     Baseline examination. Patients should undergo a comprehensive ophthalmic examination, with the eyes dilated, within 1–2 years of starting therapy. They should complete a statement of informed consent regarding possible permanent visual prob-lems in rare instances. This baseline examination should include visual acuity testing, testing with Amsler grids (with instructions for monthly home use) and color vision testing (preferably including the blue–yellow axis, using equipment such as the pseudo-isochromatic plates for color by American Optical Corporation). If any macular abnormal-ity is seen, it would be ideal to obtain fundus photographs. If progressive ocular abnormality is suspected, a baseline Humphrey 10-2 or other auto-mated perimetry test should be considered.

·     Follow-up examinations. If the patient is not obese, frail, elderly or extremely thin; does not have significant liver or kidney disease or macular disease of any type; and is below age 40, another complete examination is not necessary for 2–4 years. Patients should return sooner if

– they experience any persistent visual symptoms or

– their dosage exceeds 6.5 mg/kg.

·     If between 40 and 64 years:

– Same as above. Should be seen every 2–4 years.

·     If age 64 and above:

– Same as above. Should be seen every 2–4 years.

·     Annual examinations should be done if

– Therapy continues for longer than 5 years.

– Patient is obese or lean and small – especially elderly.

– Progressive macular disease of any type.

– Significant kidney or liver disease is present.

– Dosage exceeds 6.5 mg/kg.

·     Follow-up examinations:

– Repeat baseline examination.

– Fundus photography if any macular abnormality noted.

– Consider fluorescein angiography only if suspect pigmentary changes of any cause.

– Automated central visual fields.

– If available, but not essential, in selected cases, multifocal electroretinogram (ERG).

Chloroquine

Perform same tests as above. See at least annually if dosage is less than 3.0 mg/kg of ideal body weight. See every 6 months if dosage is greater than 3.0 mg/kg body weight, if short/obese or if kidney and/or liver impairment is present.