Observations on Experimental Chloroquine Retinopathy

Pharmacology of Chloroquine and Hydroxychloroquine

“…Chloroquine did not affect mitochondrial respiration and oxidative phosphorylation in mouse-liver homogenates or rat-liver mitochondria [ 90 ]. Neither did it affect adenosine triphosphate activity of cow visual pigment extracts [ 174 ]. Chloroquine did not affect the internalization of oligonucleotides via acidifi ed vesicles [ 173 ].…”

Ultrastructural Changes in the Rat Photoreceptor Inner Segment During Experimental Chloroquine Retinopathy

“…This dose was well above the average dose used by Me Connf.ll [16) in the previous experiment where a significant ERG reduction was reported without histological finding.…”

“…Whatever the primary origin of death in the inner segment, the early sen sitivity of inner segment metabolism to chloroquine poisoning, in some cases with little or no change in the outer segments, may explain why ERG de pression was earlier observed with no detectable change in morphology [16]. It is perhaps during this period that visual impairment may be reversible-as reported by some investigators for humans [12][13][14].…”

“…O k u n et al [9] reported a reduction of ERG in human patients who had clinical symptoms of chloroquine retinopathy. Me C o n n ell et al [16] re ported similar ERG reduction in poisoned rats, but no histological evidence capable of explaining the reduced ERG pattern was found.…”

Hydroxychloroquine and Chloroquine Retinopathy

“…Although in animal experiments with rats and cats, ERG amplitudes decrease with increasing chloroquine doses, in a rhesus monkey model of chloroquine retinopathy, there was no global ERG effect despite clear histopathological changes [190]. In clinical practice global electroretinography is insensitive to 4AQR [2,7,43,191,192]. Many clinical cases have been reported with normal ERGs [2,5,8,148].…”