Retinal toxicity due to canthaxanthin. Case series. / Toxicidad retinal por cantaxantina. Serie de casos.

INTRODUCTION: Canthaxanthin is a chemical product used to tan the skin. Its most frequent adverse effect is canthaxanthin retinopathy. PURPOSE/ METHODS: Report, case series. RESULTS: Two female patients, one 42 years-old and the other 72 years-old, with signs of retinopathy due to canthaxanthin. Complete ophthalmology examinations were carried out. The peripheral fovea birefringent deposits with internal retinal involvement were studied using multimodal imaging. CONCLUSION: Canthaxanthin retinopathy is rare. Multimodal imaging may provide important data for the differential diagnosis of crystalline retinopathy.

Inhibitory effects of astaxanthin, ß-cryptoxanthin, canthaxanthin, lutein, and zeaxanthin on cytochrome P450 enzyme activities.

Astaxanthin, ß-cryptoxanthin, canthaxanthin, lutein and zeaxanthin, the major xanthophylls, are widely used in food, medicine, and health care products. To date, no studies regarding the inhibitory effects of these xanthophylls on the nine CYPs isozymes have been reported. This study investigated the reversible and time-dependent inhibitory potentials of five xanthophylls on CYPs activities in vitro. The reversible inhibition results showed that the five compounds had only a weak inhibitory effect on the nine CYPs. Lutein did not inhibit the nine CYPs activities. Astaxanthin weakly inhibited CYP2C19, with an IC50 of 16.2 µM; and ß-cryptoxanthin weakly inhibited CYP2C8, with an IC50 of 13.8 µM. In addition, canthaxanthin weakly inhibited CYP2C19 and CYP3A4/5, with IC50 values of 10.9 and 13.9 µM, respectively. Zeaxanthin weakly inhibited CYP3A4/5, with an IC50 of 15.5 µM. However, these IC50 values were markedly greater than the Cmax values reported in humans. No significant IC50 shift was observed in the time-dependent inhibition screening. Based on these observations, it is unlikely that these five xanthophylls from the diet or nutritional supplements alter the pharmacokinetics of drugs metabolized by CYPs. These findings provide some useful information for the safe use of these five xanthophylls in clinical practice.

Canthaxanthin retinopathy: long-term observations.

PURPOSE: To describe the long-term outcome of canthaxanthin retinopathy. METHODS: We identified 13 patients with small golden particles near the macular region among a group of 35 patients with known consumption of canthaxanthin somewhen between 1983 and 1988. One long-term follow-up examination was possible in 5 of 13 cases after 16-24 years. The examinations included determination of visual acuity, the Amsler grid, slit lamp examination, perimetry, electro-oculography, electroretinography, optical coherence tomography and fluorescein angiography. RESULTS: Complete disappearance of the golden particles took approximately 20 years. The patients in our study were asymptomatic and no functional defect related to canthaxanthin could be detected. CONCLUSIONS: Ingestion of canthaxanthin causes no long-term adverse effects.

[Crystalline retinopathy]. / Les rétinopathies cristallines.

Crystalline retinopathy is characterized by intraretinal crystalline deposits that, according to their etiology, can be localized in the macular area or, indeed, be found in the entire retina. These deposits can be associated or not to visual loss and electrophysiological perturbations. Among the toxic drugs leading to this retinopathy are tamoxifen, canthaxanthine, methoxyflurane, talc and nitrofurantoin. A detailed description of tamoxifen and canthaxanthine toxicity is reported in this chapter.

Ultrahigh-resolution optical coherence tomography of canthaxanthine retinal crystals.

A case of crystalline retinopathy caused by prolonged ingestion of an oral tanning agent containing canthaxanthine is described. Color fundus photography and ultrahigh-resolution optical coherence tomography were performed.

Canthaxanthine retinopathy.

BACKGROUND: A 42-year-old white female complaining of decreased vision was examined and small golden particles were found in the macular regions of both eyes. It was ascertained that the patient had been using an oral bronzing agent, canthaxanthine (Orobronze), for the previous 10 years. METHODS: The method of deposition of these crystalline particles and their possible sequela are presented. The differential diagnosis of this condition is also described. RESULTS: In this case a crystalline retinopathy was induced by the oral ingestion of a bronzing agent. CONCLUSIONS: Although the gold-like particles have no visual consequences, it is important for the clinician and the patient to be aware of their etiology.

Asymmetric canthaxanthin retinopathy.

PURPOSE/METHODS: We studied a case of crystalline retinopathy occurring after prolonged use of oral canthaxanthin. The patient was followed up for 38 months during which time she sustained a branch retinal vein occlusion in her left eye. RESULTS/CONCLUSIONS: An asymmetric appearance to the crystalline deposition was noted with increased sedimentation seen in the left eye. Vascular alterations after a branch retinal vein occlusion may lead to local stasis that may exacerbate the development of canthaxanthin retinopathy.

Idiopathic canthaxanthine retinopathy.

An unusual case of canthaxanthine retinopathy is described. The usual aetiological factors were absent, ingested dietary canthaxanthine is implicated as a possible cause.

[Canthaxanthin retinopathy. Follow-up of over 6 years]. / Canthaxanthin-Retinopathie. Verlaufskontrolle nach über 6 Jahren.

After long-term treatment with high dosages, canthaxanthin causes a characteristic retinopathy with circular, macula surrounding crystals. As changes in retinal functionning disappear relatively easily after withdrawal of the drug, the crystals dissolve rather slowly--over about several years. Five patients showing a profound crystalline retinopathy were re-examined with an average of 69.7 months after withdrawal of the canthaxanthin-containing drug. Three of the patients were treated for erythropoetic protoporphyria (EPP) with Phenoro (2/5 beta-carotene, 3/5 canthaxanthin), two sisters took a canthaxanthin-containing formulation (1/8 beta-carotene, 7/8 canthaxanthin) for cosmetic reasons. Two female patients complained about an increased glare sensitivity, which was explainable for one of them with a subcapsular cataract. The retinal crystals decreased quite differently. Minor deffects of the retinal pigment epithelium remained unchanged in two patients. They increased slightly in the female patient with the smallest crystal formation but highest plasma cholesterol. Shortly after withdrawal of the drugs usually an increase of a-wave amplituded of the electroretinograms was found. The a-waves returned to normal and the b-wave amplitudes showed an increase up to the final control paralleling the reduction of the retinal crystals. A- and b-wave peak latencies which were prolonged under treatment returned to normal.