[Chloroquine/hydroxychloroquine: variability of retinotoxic cumulative doses].
OBJECTIVE
The critical dose of chloroquine/hydroxychloroquine leading to a maculopathy or generalised retinopathy remains undetermined. In the literature, 100 g is considered the dose at which regular vision checks should be performed. Generally, chloroquine is said to be more toxic than hydroxychloroquine. A young patient presenting with toxic maculopathy after 57 g of hydroxychloroquine and a daily dosage of 2 mg/kg body weight prompted us to retrospectively look at our patients examined in this respect over about 1 year.


METHODS
The data of patients who were examined because of chloroquine/hydroxychloroquine intake or a respective maculopathy/retinopathy were retrospectively analysed. The time period was January 2005 until March 2006. Retinal damage was defined by fundus changes and alteration of the multifocal electroretinogram (ERG).


RESULTS
Twenty-one patients--18 women and three men--were examined. The mean age was 51 years (range 6-71). Five of the nine chloroquine-treated patients developed a maculopathy, and one of them developed an additional generalised retinopathy. Of the patients treated by hydroxychloroquine, three of 12 suffered from a maculopathy and one from an additional generalised retinopathy. The cumulative doses leading to retinal damage ranged from 170 g to 1650 g for chloroquine and from 57 g to 1190 g for hydroxychloroquine. The highest cumulative doses without leading to signs of retinopathy were 790 g for chloroquine and 1200 g for hydroxychloroquine.


CONCLUSIONS
There is a high variability of cumulative doses of chloroquine/hydroxychloroquine that lead to a toxic retinopathy. Therefore, early and regular ophthalmologic examinations are recommended. Electrophysiological testing should be performed once a year, corresponding to about 60 g of base with one tablet a day. For electrophysiology, the multifocal ERG has turned out to be the most important test in this regard. However, visual acuity and funduscopy should be performed more frequently.
Rüther
K
K
Charitè-Augenklinik Campus Virchow Klinikum, Augustenburger Platz 1, 13353, Berlin. klaus.ruether@charite.de
Foerster
J
J
Berndt
S
S
Schroeter
J
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000633:toxicity*; D001379:Azathioprine / Q000008:administration & dosage / Q000633:toxicity; D002648:Child; D002738:Chloroquine / Q000008:administration & dosage / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D004596:Electroretinography / Q000187:drug effects; D005260:Female; D005654:Fundus Oculi; D006801:Humans; D006886:Hydroxychloroquine / Q000008:administration & dosage / Q000633:toxicity*; D008134:Long-Term Care; D008180:Lupus Erythematosus, Systemic / Q000188:drug therapy*; D008266:Macula Lutea / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D009887:Ophthalmoscopy; D011239:Prednisolone / Q000008:administration & dosage / Q000633:toxicity; D012160:Retina / Q000187:drug effects*; D012164:Retinal Diseases / Q000139:chemically induced* / Q000175:diagnosis; D014794:Visual Fields / Q000187:drug effects
D018501:Antirheumatic Agents; D006886:Hydroxychloroquine; D002738:Chloroquine; D011239:Prednisolone; D001379:Azathioprine