Closantel retinal toxicity: Recovery from severe vision loss after corticosteroid therapy

Abstract

Purpose To present a relatively rare case of retinal toxicity and consequent severe vision loss due to Closantel ingestion. Case report A 37-year-old female presented with sudden painless decrease vision in both eyes. She had no previous history of medical disease and denied any trauma. The patient had accidentally ingested Closantel a few days prior to presentation. Closantel is a veterinary anti-helminthic drug used mainly in livestock. Best corrected visual acuity (BCVA) at presentation was 20/200 bilaterally. There was no relative afferent pupillary defect (RAPD) and red saturation test was normal. Macular optical coherence tomography (OCT) revealed disruption in the outer retinal layer and ellipsoid zone in both eyes. A diagnosis of retinal toxicity due to Closantel was made and the patient was started on 1 mg/kg oral prednisolone acetate. On the 45th day after presentation, her BCVA had improved to 20/20 bilaterally. Conclusion Closantel is a potentially toxic drug causing destruction of the neurosensory retina and visual disturbances. We suggest eye-care personnel awareness regarding the risk of Closantel-induced retinal toxicity and prompt treatment with systemic steroids should be considered.

Optical coherence tomography findings in presumed veterinary anthelmintic drug-induced retinal toxicity: a glimpse into underlying mechanism

“…According to previous case reports of closantel poisoning, early initiation of plasmapheresis or systemic corticosteroids could contribute to considerable visual recovery. 11,13,28–30 However, despite multiple therapeutic attempts, the visual outcome was deemed poor in all of our patients except Case 4. The exact reason for the better visual acuity in this case is not well understood, while the shorter duration of drug intake (only 1 day) followed by rapid stomach lavage may have limited further drug exposure and toxic effects on the retina.…”

“…27 Two case reports of closantel poisoning have also described a disruption in the EZ, which is densely packed with mitochondria and is thus important for the photoreceptor health and function. 11,12 Similarly, we initially discovered abnormal reflectivity in the EZ in two patients. Recently, veterinary niclosamide, also an oxidative phosphorylation uncoupler, was connected to a case of bull's-eye maculopathy with parafoveal EZ disruption and outer retinal thinning, a condition comparable with closantel poisoning.…”

“…This finding is comparable with four previous case reports of closantel retinal toxicity that included initial OCT pictures. 10–13 Moreover, the abnormal reflectivity pattern on OCT seen in these patients appears to be a morphologic marker of diffuse photoreceptor swelling up to the junction with the bipolar cells. With time, the outer retinal hyperreflectivity subsided and the photoreceptor cell necrosis developed, as revealed by the histologic analysis of closantel-poisoned animals.…”

The Antifungal Potential of Niclosamide and Structurally Related Salicylanilides

“…Severe visual disorders and retinopathies were described in humans who have consumed higher (toxic) doses of salicylanilide drugs such as niclosamide or closantel [ 84 , 85 ]. These visual adverse effects can be reversible and were treated successfully with corticosteroids [ 127 ]. However, the risk to induce retinopathy by a new antifungal drug should be minimal and needs to be considered for the development of niclosamide and salicylanilide antimycotics in the future.…”