Amantadine can induce intra-epithelial deposition in the cornea

Metabolic profiling to evaluate the impact of amantadine and rimantadine on the secondary metabolism of a model organism

Metabolic profiling offers huge potential to highlight markers and mechanisms in support of toxicology and pathology investigations during drug development. The main objective was to modify therapy with adamantane derivatives: amantadine and rimantadine, to increase their bioavailability and evaluate the influence of such therapy on drug metabolism using Saccharomyces cerevisiae as the model organism. In this study, the profile of endogenous metabolites of a model organism was measured and interpreted to provide an opportunity to investigate changes induced by treatment with amantadine and rimantadine. It was found that resveratrol supplementation synergistically enhanced the effects of amantadine treatment and increased rimantadine metabolism, potentially reducing side effects. The fingerprinting strategy was used as an efficient technique for qualitatively evaluating and monitoring changes in the profiles of endogenous components and their contents in a model organism. Chemometric tools were employed to find marker compounds that can be defined as characteristic indicators of a pharmacological response to a therapeutic intervention. An improved understanding of the mechanisms involved in drug effect and an increased ability to predict individual variations in the drug response of organisms will improve the treatment process and the development of new therapies.

Ocular Surface Features in Patients with Parkinson Disease on and off Treatment: A Narrative Review

Parkinson disease (PD) is a progressive, neurodegenerative disease of the central nervous system. Visual disturbance is one of the most frequent nonmotor abnormalities referred to by patients suffering from PD at early stages. Furthermore, ocular surface alterations including mainly dry eye and blink reduction represent another common finding in patients with PD. Tears of PD patients show specific alterations related to protein composition, and in vivo confocal microscopy has demonstrated profound changes in different corneal layers in this setting. These changes can be attributed not only to the disease itself, but also to the medications used for its management. In particular, signs of corneal toxicity, both at epithelial and endothelial level, are well described in the literature in PD patients receiving amantadine. Management of PD patients from the ophthalmologist's side requires knowledge of the common, but often underdiagnosed, ocular surface alterations as well as of the signs of drug toxicity. Furthermore, ocular surface biomarkers can be useful for the early diagnosis of PD as well as for monitoring the degree of neural degeneration over time.

Amantadine therapy for Parkinson's Disease: In Vivo Confocal Microscopy corneal findings, case report and revision of literature

BACKGROUND

To report a case of a patient showing bilateral corneal opacities after amantadine chronic treatment for Parkinson's Disease (PD) and corneal edema associated with intra-epithelial and -endothelial depositions. After amantadine discontinuation a complete clinical remission with only a partial ultrastructural corneal recovery was reported.

CASE PRESENTATION

We describe a 78-year-old man with non-medical-responding bilateral corneal edema in treatment with systemic Amantadine for PD. In vivo confocal Microscopy (IVCM) analysis revealed hyperreflective particles at the epithelial level and expanded hyperreflective keratocyte and a disarrangement of stromal lamellae; endothelial cells showed hyperreflective intracellular inclusions in central and in peripheral areas with central polymegatism and pleomorphism. After 1 and 6 months the amantadine discontinuation, the absence of bilateral corneal edema and opacities were noted at the slit lamp examination, associated with the disappearance of epithelial and stromal abnormalities, but the persistence of endothelial hyperreflective deposits with a pleomorphism and polymegatism worsening at the IVCM exam.

CONCLUSION

The evaluation of a patient's cornea 6 months after the discontinuation of systemic amantadine therapy showed a clinical complete remission, with a complete resolution of the bilateral corneal oedema. On the other hand, ultrastructurally, amantadine toxicity is a completely reversible phenomenon at the epithelial level; conversely IVCM showed persistent endothelial degradation.

Drug-induced corneal deposits: an up-to-date review

This review assesses different clinical aspects of the various known drug-induced corneal deposits, based on the corneal layer involved (epithelium, stroma and/or endothelium), and based on the drug class. The most well-known condition caused by drug deposits is vortex keratopathy, or corneal verticillata, which is a whorl-like opacity in the corneal epithelium. Vortex keratopathy is commonly caused by certain cationic amphiphilic drugs such as amiodarone, antimalarials, suramin, tamoxifen, chlorpromazine and non-steroidal anti-inflammatory drugs. These deposits usually occur once a certain dose of the drug is reached. Most cases present with mild to moderate symptoms with minimal visual impairment. Most of these deposits resolve automatically, after months to years of drug cessation. Notably, other drug classes can cause deposits in all three layers of the cornea. Chlorpromazine, gold, rifabutin, indomethacin and tyrosine kinase inhibitors can cause stromal deposits, with reduced visual acuity when the anterior stroma is involved. Chlorpromazine and rifabutin can also cause deposits in the endothelial layer of the cornea. Regardless of the type of corneal deposit, local therapies such as topical lubricants or corticosteroids may help improve symptoms. Drug cessation or modification can also be helpful but should be weighed against the systemic risks of the underlying disease.