Management of patients undergoing hydroxychloroquine (Plaquenil) therapy

Pharmacology of Chloroquine and Hydroxychloroquine

The 4-aminoquinolines are weak bases that are completely absorbed from the gastrointestinal tract, sequestered in peripheral tissues, metabolized in the liver to pharmacologically active by-products, and excreted via the kidneys and the feces. The parent drugs and metabolites are excreted with a half-life of elimination of approximately 40 days. However, slow release from sequestered stores of the drugs means that after discontinuation, they continue to be released into the plasma for years. Correct dosing is based on the ideal body weight of the patient, which depends on height. The 4AQs diminish autoimmunity without compromising immunity to infections.

Retinal disorders in northern Brazilian patients treated with chloroquine assessed by multifocal ERG

The effects of chloroquine intake on the retinal function in a Brazilian population of patients were assessed by multifocal electroretinography. Twenty-four randomly chosen eyes of patients treated with chloroquine for rheumatoid arthritis and systemic lupus erythematosus were examined using multifocal electroretinography (mfERG). Control measurements were acquired from 21 randomly chosen eyes of age-matched healthy subjects. None of the study participants had an inherited retinal disease or a Snellen visual acuity reduced to less than 20/40. In patients and control subjects, cumulative chloroquine dose, total daily dose, duration of treatment, retinal examination, visual field defects, visual acuity, and the mfERG were assessed. The average amplitudes and implicit times of the N1, P1, and P2 components of the mfERGs were measured in the central hexagon (R1) and in five rings (R2-R6). The values measured in patients and normal subjects were compared. The P1 amplitudes in R2 were significantly decreased in the patients. In addition, the amplitudes of N1 and N2 in R1 were significantly smaller in the patients. The implicit times of none of the components were significantly different between patients and controls. The response amplitude was not significantly correlated with cumulative dose and duration of intake. There was no correlation with retinal appearance, visual field, and visual acuity. In agreement with earlier data, the central mfERG amplitudes were decreased in chloroquine patients indicating functional alterations in the retina. These changes are also present in a Brazilian population suggesting that the effects of chloroquine are general and that genetic background and life circumstances probably have, if at all, only little effect.

Sarcoidosis: case report and review

Sarcoidosis is a granulomatous disorder of uncertain aetiology that can affect almost any organ. Anterior uveitis is a feature of the condition in about 30 per cent of those affected. We describe a patient with sarcoidosis presenting with anterior uveitis and describe a diagnostic approach. Sarcoidosis is a condition that must be considered in patients presenting with symptomatic uveitis, as the underlying disease is serious and usually treatable. The diagnosis of sarcoidosis is aided by an understanding of the pattern of organ involvement and may ultimately require tissue confirmation through biopsy of granulomata, including those found in the ocular adnexa.

Ocular Toxicity Due to Chloroquine and Hydroxychloroquine: Electrophysiological and Visual Function Correlates

Chloroquine (CQ) and hydroxycholorquine (HCQ) have been used widely for the treatment of rheumatoid arthritis and other similar inflammatory diseases since the early 50s. They remain the treatment of choice for many patients even today. Significant, either reversible or irreversible central visual loss associated with the drugs is very rare, but an important side effect that can warrant discontinuation of therapy. Early diagnosis of toxicity and evaluation of the visual function are, therefore, important parts of the treatment process. Various electrophysiological and psychophysical tests have been and are used for the detection, follow-up and prognosis of drug-associated central visual loss. A summary and comment on the tests, with emphasis on the use of more recently developed methods, such as the multifocal electroretinography (mfERG), are presented in this review.