Screening for hydroxychloroquine retinopathy. Screening should be selective

Relative sensitivity and specificity of 10-2 visual fields, multifocal electroretinography, and spectral domain optical coherence tomography in detecting hydroxychloroquine and chloroquine retinopathy

BACKGROUND

The purpose of this study was to determine the relative sensitivity and specificity of 10-2 visual fields (10-2 VFs), multifocal electroretinography (mfERG), and spectral domain optical coherence tomography (SD-OCT) in detecting hydroxychloroquine retinopathy.

METHODS

A total of 121 patients taking hydroxychloroquine (n=119) or chloroquine (n=2) with 10-2 VF, mfERG, and SD-OCT tests were retrospectively reviewed. Rates of test abnormality were determined.

RESULTS

Retinopathy was present in 14 and absent in 107. Eleven of 14 (78.6%) patients with retinopathy were overdosed. Twelve (85.7%) had cumulative dosing greater than 1,000 g. The sensitivities of 10-2 VF, mfERG, and SD-OCT in detecting retinopathy were 85.7%, 92.9%, and 78.6%, respectively. The specificities of 10-2 VF, mfERG, and SD-OCT in detecting retinopathy were 92.5%, 86.9%, and 98.1%, respectively. Positive predictive values of 10-2 VF, mfERG, and SD-OCT in detecting retinopathy were less than 30% for all estimates of hydroxychloroquine retinopathy prevalence. Negative predictive values were >99% for all tests.

CONCLUSION

Based on published estimates of hydroxychloroquine retinopathy prevalence, all three tests are most reliable when negative, allowing confident exclusion of retinopathy in patients taking ≤6.5 mg/kg/day. Each test is less useful in allowing a confident diagnosis of retinopathy when positive, especially in patients taking ≤6.5 mg/kg/day.

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.

Population pharmacokinetics of hydroxychloroquine in patients with rheumatoid arthritis

SUMMARY

Hydroxychloroquine (HCQ) is an antimalarial drug that is also used as a second-line treatment of rheumatoid arthritis (RA). Clinically, the use of HCQ is characterized by a long delay in the onset of action, and withdrawal of treatment is often a result of inefficacy rather than from toxicity. The slow onset of action can be attributed to the pharmacokinetics (PK) of HCQ, and wide interpatient variability is evident. Tentative relationships between concentration and effect have been made, but to date, no population PK model has been developed for HCQ. This study aimed to develop a population PK model including an estimation of the oral bioavailability of HCQ. In addition, the effects of the coadministration of methotrexate on the PK of HCQ were examined. Hydroxychloroquine blood concentration data were combined from previous pharmacokinetic studies in patients with rheumatoid arthritis. A total of 123 patients were studied, giving the data cohort from four previously published studies. Two groups of patients were included: 74 received hydroxychloroquine (HCQ) alone, and 49 received HCQ and methotrexate (MTX). All data analyses were carried out using the NONMEM program. A one-compartment PK model was supported, rather than a three-compartment model as previously published, probably because of the clustering of concentrations taken at the end of a dosing interval. The population estimate of bioavailability of 0.75 (0.07), n = 9, was consistent with literature values. The parameter values from the final model were: Cl = 9.9 +/- 0.4 L/h, V = 605 +/- 91 L, ka = 0.77 +/- 0.22 hours(-1), t(tag) = 0.44 +/- 0.02 hours. Clearance was not affected by the presence of MTX, and, hence, steady-state drug concentrations and maintenance dosage requirements were similar. A population PK model was successfully developed for HCQ.

Hydroxychloroquine and chloroquine retinopathy: screening for drug toxicity

PURPOSE

To report hydroxychloroquine and chloroquine retinopathy and consider screening for drug toxicity.

DESIGN

Retrospective observational case series.

METHODS

Review of clinical records, visual fields, fundus photographs, and fluorescein angiography of six patients from a retina referral practice.

RESULTS

All cases arose because of failure by physicians to avoid dosing above published safe levels. Five cases developed despite accepted ophthalmologic patterns of screening for toxicity. All cases developed parafoveal retinal pigment epithelial atrophic changes and paracentral scotomas to threshold visual field testing.

CONCLUSIONS

New cases of hydroxychloroquine and chloroquine toxicity continue to develop in a screening environment. Increased ophthalmologic attention to dosing, awareness of location and nature of early visual field defects, and traditional attention to presence or absence of maculopathy can reduce the incidence of this avoidable condition.

Early hydroxychloroquine macular toxicity

This report describes the case of an appropriately dosed patient who developed maculopathy <8 years after starting hydroxychloroquine (HCQ) therapy for systemic lupus erythematosus. Risk factors and screening for HCQ-associated maculopathy are discussed.