Linezolid-Induced Toxic Optic Neuropathy

Study of adverse drug reactions during the treatment of drug resistant tuberculosis

BACKGROUND

Pharmacovigilance entails monitoring of patients for timely detection of ADR and reporting them so that more information about drug safety can be obtained. This may help in the future for dose modification or alteration of regimen. In NTEP, ADSm (Active Drug Safety monitoring) is part of pharmacovigilance. In this study we shall be studying ADRs to Anti TB drugs in DRTB.

METHODOLOGY

This study is observational, retrospective and record based, of patients admitted from 2021 to 2023 in the DOTS ward of Respiratory Medicine Department of a tertiary care hospital in Goa. Data such as age, sex, regimen, date of AKT initiation and adverse effects documented has been noted and compiled.

RESULTS

ADRs have been tabulated in the form of tables. Statistical analysis is done to find out the commonest ADR, time when they are likely to occur, which age and gender are most likely affected and if there are any other associated risk factors for ADRs.

CONCLUSION

This study will enable in future to better monitor patients with regard to particular adverse drug reaction, patient safety and if needed to alter the regimen as early as possible.

Linezolid toxic optic neuropathy: A case report and review of visual prognosis

Purpose

To describe a case of linezolid toxic optic neuropathy in a 71-year-old female and review the relevant literature.

Observations

An adult female with progressive, symmetric vision loss was hypothesized to have linezolid toxic optic neuropathy. Following cessation of linezolid, the patient experienced improvement in visual function over two months.

Conclusions and importance

Patients diagnosed with linezolid toxic optic neuropathy can expect some return of visual function after cessation. The degree of return does not correlate to the cumulative dose of the drug. The goal of this study was to summarize and add to the current body of literature on the topic.

The Neuro-Ophthalmology of Tuberculosis

Tuberculosis (TB) is a global health concern and central nervous system (CNS) TB leads to high mortality and morbidity. CNS TB can manifest as tubercular meningitis, tuberculoma, myelitis, and arachnoiditis. Neuro-ophthalmological involvement by TB can lead to permanent blindness, ocular nerve palsies and gaze restriction. Visual impairment is a dreaded complication of tubercular meningitis (TBM), which can result from visual pathway involvement at different levels with varying pathogenesis. Efferent pathway involvement includes cranial nerve palsies and disorders of gaze. The purpose of this review is to outline the various neuro-ophthalmological manifestations of TB along with a description of their unique pathogenesis and management. Optochiasmatic arachnoiditis and tuberculomas are the most common causes of vision loss followed by chronic papilloedema. Abducens nerve palsy is the most commonly seen ocular nerve palsy in TBM. Gaze palsies with deficits in saccades and pursuits can occur due to brainstem tuberculomas. Corticosteroids are the cornerstone in the management of paradoxical reactions, but other immunomodulators such as thalidomide and infliximab are being explored. Toxic optic neuropathy caused by ethambutol necessitates careful monitoring and immediate drug discontinuation. Cerebrospinal fluid diversion through ventriculo-peritoneal shunting may be required in patients with hydrocephalus in stage I and II of TBM to prevent visual impairment. Early diagnosis and prompt management are crucial to prevent permanent disability. Prevention strategies, public health initiatives, regular follow-up and timely intervention are essential in reducing the burden of CNS TB and its neuro-ophthalmological complications.

A phase I study of the safety, tolerability, and pharmacokinetics of contezolid acefosamil after intravenous and oral administration in healthy Chinese subjects

Contezolid acefosamil (also known as MRX-4), a prodrug of contezolid, is under development for treatment of multidrug-resistant Gram-positive bacterial infections. A phase I single ascending dose (SAD) and multiple-dose placebo-controlled study was conducted to assess the safety, tolerability, and pharmacokinetics (PK) of contezolid acefosamil in healthy Chinese subjects following intravenous (IV) and oral administration. Adverse events (AEs) and PK parameters were assessed appropriately. All subjects (n = 70) completed the trial. Overall, 67 cases of treatment-emergent adverse events (TEAEs) were observed in 49.1% (27 of 55) of the subjects receiving contezolid acefosamil. All TEAEs were mild in severity. No serious AEs or deaths were reported. After IV SAD (500-2,000 mg), the corresponding C max of the active drug contezolid increased from 1.95 ± 0.57 to 15.61 ± 4.88 mg/L, AUC0-inf from 40.25 ± 10.12 to 129.41 ± 38.30 h·mg/L, median T max from 2.00 to 2.75 h, and mean t 1/2 from 13.33 to 16.74 h. Plasma contezolid reached steady state on day 6 after multiple IV doses, with an accumulation ratio of 2.20-2.96. Oral SAD of 500 and 1,500 mg resulted in contezolid C max of 8.66 ± 2.60 and 37.10 ± 8.66 mg/L, AUC0-inf of 30.44 ± 7.33 and 162.36 ± 47.08 h·mg/L, and median T max of 2.50 and 2.98 h. Contezolid reached steady state on day 5 after multiple oral doses of 1,500 mg without significant accumulation. Contezolid C max and AUC0-inf increased with the dose of contezolid acefosamil. The good safety and PK profiles in this SAD and multiple-dose study can support further clinical development of contezolid acefosamil.

Linezolid optic neuropathy

PURPOSE OF REVIEW

In this article, we reviewed 67 reported cases of linezolid optic neuropathy and describe the common characteristics and expectations for recovery with an emphasis on recent findings in the literature.

RECENT FINDINGS

Linezolid classically causes a reversible, duration-dependent optic neuropathy. However, in our review, we found only 66.7% of patients recovered complete visual function. Vision loss most commonly affected visual acuity followed by visual field and color vision. We also found patients taking higher doses of linezolid experienced full recovery less often, suggesting a dose-dependent component of linezolid optic neuropathy. Linezolid use has increased in frequency and duration, especially in the treatment of drug-resistant tuberculosis, and data indicate that these patients experience lower rates of complete vision recovery compared with patients taking linezolid for other indications.

SUMMARY

Linezolid is an effective medication for treating drug-resistant infections; however, it may result in optic neuropathy. It is reasonable for patients on linezolid to undergo screening examinations, especially those on higher doses or for prolonged duration of therapy.

Oxidative Stress in Antibiotic Toxic Optic Neuropathy Mimicking Acute LHON in a Patient with Exacerbation of Cystic Fibrosis

The striking similarity of disc edema without leakage on fluorescein angiography, which is pathognomonic of Leber hereditary optic neuropathy (LHON), was present in a patient with cystic fibrosis with antibiotic toxic optic neuropathy. This similarity suggested the common effect of oxidative stress on retinal ganglion cells in inherited mitochondrial and antibiotic optic neuropathies. We present the case of a patient with advanced cystic fibrosis on chronic antibiotic treatment who experienced a rapid painless bilateral visual decline over a course of a few weeks. At examination, his corrected visual acuity was reduced to 0.3 in both eyes, with dyschromatopsia and central scotoma. The appearance of the fundus resembled the typical clinical features of acute LHON with hyperemic optic discs and tortuous vessels with no dye leakage from the optic discs on fluorescein angiography. Ganglion cell layer loss was seen on optic coherence tomography, with all findings pointing to LHON. Genetic testing did not reveal any LHON-specific mutations. After extended genetic testing, a heterozygous variant c.209C>T in the OPA3 gene on chromosome 19, g.46032648G>A, classified as a variant of unknown significance, was also found. After discontinuing antibiotics and general improvements in his health, surprisingly, his visual function completely improved. Later, he also received a bilateral lung transplant that further improved his general condition, and his vision remained normal. Excluding LHON, the transient optic neuropathy in our patient could be mainly due to antibiotic toxicity of linezolid and ciprofloxacin, which have been linked to mitochondrial dysfunction and advanced cystic fibrosis with hypoxic status. We suggest the possibility that patients with cystic fibrosis may be more prone to developing mitochondrial optic neuropathy, especially with additional risk factors such as chronic antibiotic therapy, which affect mitochondrial function, and can perhaps serve as a model for LHON.