Visual Recovery Time in Patients with Ethambutol-induced Toxic Optic Neuropathy

PURPOSE

We aimed to investigate the visual recovery time in patients with ethambutol-induced toxic optic neuropathy (EON) and identify the factors associated with the visual recovery time.

METHODS

In this retrospective cohort study, we reviewed the medical records of 35 eyes from 35 patients with EON. Visual recovery was defined as a gain of three or more lines from the nadir.

RESULTS

Patients were observed following discontinuation of ethambutol (EMB), with the mean follow-up period of 21.0 ± 16.0 months. The visual acuity at nadir was logarithm of the minimum angle of resolution 1.4 ± 0.4, and the final visual acuity was logarithm of the minimum angle of resolution 0.6 ± 0.5. Twenty-seven eyes (77.1%) showed significant visual recovery. In Kaplan-Meier survival, the mean estimated time for visual recovery was 15.2 ± 3.0 months, and 50% of the patients experienced visual recovery at 8.3 ± 2.2 months following EMB discontinuation. Multivariate Cox regression analysis identified several significant risk factors for delayed visual recovery, including duration of EMB medication ≤6 months, period from symptom onset to EMB discontinuation >14 days, and baseline peripapillary retinal nerve fiber layer thickness >98 μm.

CONCLUSIONS

Our study indicated a mean time of visual recovery of 15 months for EON cases. Therefore, patients diagnosed with EON should be followed up for more than 1 to 2 years to evaluate their visual recovery. Delayed EMB discontinuation, short duration of EMB use, and initial peripapillary retinal nerve fiber layer thickening were associated with delayed visual recovery. Therefore, patients taking EMB should be followed up regularly for early detection of EON and immediate discontinuation of EMB to prevent severe damage to the optic nerve.

Efficacy and safety of rifampicin-based triple therapy for non-puerperal mastitis: A single-arm, open-label, prospective clinical trial

OBJECTIVES

To assess the efficacy and safety of rifampicin-based triple therapy (rifampicin, isoniazid, and ethambutol) for treating NPM.

METHODS

This single-center, single-arm, prospective clinical trial was conducted at the Second Hospital of Shandong University (Jinan, China). Patients with pathologically diagnosed granulomatous lobular mastitis and periductal mastitis received triple drugs, i.e., rifampicin (450 mg/day), isoniazid (300 mg/day), and ethambutol (15 mg/kg/day), until complete response or the investigator decided to discontinue treatment. The primary endpoint was the complete response rate (CRR) assessed by the investigator. The secondary endpoints included the overall remission rate (ORR), recurrence rate (RR), and safety.

RESULTS

A total of 218 patients were enrolled in the study between January 1, 2013 and October 31, 2020. With a median follow-up time of 48 months, the CRR and the ORR were 78.44% and 94.04%, respectively. While 13 patients (5.96%) demonstrated no response and 19 relapsed (8.72%). Adverse events (AEs) were not common. The most common AEs during treatment were liver dysfunction (1.83%), gastrointestinal reactions (1.83%), fatigue (1.83%), erythema (1.38%), and menstrual disorders (0.92%).

CONCLUSION

Rifampicin, isoniazid, and ethambutol demonstrated promising response rates with acceptable safety profiles in patients with NPM. Further confirmatory trial is warranted in the future.

TRIAL REGISTRATION

The study was approved by the Ethics Committee of the Second Hospital of Shandong University and retrospectively registered at the China Clinical Trial Registration Center (registration number: ChiCTR2100049591).

Risk of gout flare after medication: prescription symmetry sequence analysis

OBJECTIVES

The research aimed to study the following questions: (1) five well-known gout-related medications were selected to test the validity of the prescription symmetry sequence analysis in Taiwan; (2) four exploratory medications were selected to test their relation to gout flares.

METHODS

We utilized the 2003-2017 dataset of the Taiwan National Health Insurance Program containing all claims data with 2 million beneficiaries as a data source. In order to explore the temporal association, we designed a scenario of medication-induced gout flares. Nine medications were selected as the index agent, including aspirin (low-dose), thiazide diuretics, loop diuretics, ethambutol, pyrazinamide, metformin, pioglitazone, fenofibrate, and losartan. The gout flare was defined as subjects with use of the marker agent for treatment of gout flares. The observation-window period between initiation of the index agent and initiation of the marker agent was 1 year. Subjects who used an index agent and a marker agent on the same day were excluded. The prescription symmetry sequence analysis was carried out to compare the observed number of persons who took an index agent prior to starting a marker agent with the observed number of persons who took a marker agent before starting an index agent. The adjusted sequence ratio (adjusted SR) with 95% confidence interval was applied to estimate the relation between an index agent and the marker agent.

RESULTS

Among five medications including aspirin (low-dose), thiazide diuretics, loop diuretics, ethambutol, and pyrazinamide, the adjusted sequence ratio ranged from 1.15 to 3.35 and all reached statistical significance. Fenofibrate use and losartan use were associated with a lower probability of gout flares, with reaching statistical significance (adjusted SR = 0.60 for fenofibrate and adjusted SR = 0.92 for losartan). Metformin use was associated with a greater probability of gout flares, with reaching statistical significance (adjusted SR = 1.14). Pioglitazone use did not reach statistical significance.

CONCLUSION

Based on the confirmatory analysis including five well-known gout-related medications, this study supports that the prescription symmetry sequence analysis can be used to detect an adverse drug event associated with one potential offending agent. The exposure to fenofibrate or losartan might be a protective factor against gout flares. Metformin use could be associated with a greater probability of gout flares, but this finding should be validated by other studies.

KEY POINTS

• What is already known about this subject? 1. The prescription symmetry sequence analysis is a useful method for detecting an adverse drug reaction associated with one potential offending drug. 2. Numerous medications are found to induce gout flares. • What does this study add? 1. The prescription symmetry sequence analysis supports the evidence that aspirin (low-dose), thiazide diuretics, loop diuretics, ethambutol and pyrazinamide are associated with a greater probability of gout flares. 2. The exposure to fenofibrate or losartan might be a protective factor against gout flares. 3. Metformin use could be associated with a greater probability of gout flares. • How might this impact on clinical practice or future developments? 1. Clinicians should always consider the possibility of medication-induced gout flares. If gout flares develop, discontinuation of risky medications is the first step. Then prescribing cascades can be eliminated.

Ethambutol and visual assessment in England: current practice and recommendations

BACKGROUND

Standard treatment for tuberculosis (TB) in children and adults includes an initial two-month course of ethambutol, a drug that in rare cases can cause optic neuropathy and irreversible vision loss. There is a lack of clear guidance on what vision assessments are needed before and during treatment with ethambutol, with the Royal College of Ophthalmologists, National Institute for Health and Care Excellence, British National Formulary and British Thoracic Society offering different guidance. We aimed to assess how vision is routinely tested in patients treated with ethambutol in TB services across England.

METHODS

An online survey developed by Public Health England was sent to all TB services in England in 2018 to assess current practice and inform the development of best practice recommendations for visual assessment of patients treated with ethambutol for TB.

RESULTS

Sixty-six TB professionals from across England responded, a response rate of 54%. The results showed variations in practice, including when to omit ethambutol from treatment, the timing and frequency of visual assessment, the type of visual assessment, referral processes and management of visual changes.

CONCLUSION

This national survey highlights the need for clear guidelines on the testing of vision for patients taking ethambutol at recommended doses, before and during treatment. We suggest a pragmatic approach to visual assessment to reduce variation in practice, proposing a stepwise pathway for patients on standard TB treatment for local adaptation.

Ethambutol and its ophthalmic effects; is screening and collaboration the new way forward?

AIM

To screen patients on ethambutol and evaluate its role on visual functions and toxic optic neuropathy.

SETTING AND DESIGN

Retrospective, observational single tertiary centre cohort of 80 patients.

METHODS AND MATERIAL

A total of 69 from the initial 80 patients with visual complaints were categorised into two groups A and B; ongoing anti-tubercular therapy with ethambutol and having stopped ethambutol for greater than six months respectively. All patients underwent vision (V) testing on ETDRS chart and anterior and posterior segment evaluation. Additionally, patients in group A recorded color vision (CV) on Ishihara chart and visual evoked potential (VEP).

STATISTICAL ANALYSIS USED

P value was calculated using Chi square test (SPSS ver. 20).

RESULTS

Out of 69 patients in our study, 58 (84.05%) patients recorded reduced visual acuity. The mean visual acuity was 0.58 logMAR units. 33 out of our 58 (57%) patients with reduced visual acuity showed normal optic discs while 25 out of 58 (43%) showed altered optic discs. In group B, 14 out of 32 patients with vision of less than 20/20 also had optic disc pallor (p = 0.02). 12 out of 15 patients in group A recorded an altered color vision and also had a vision of less than 20/20 (p = 0.023). 15 patients who recorded altered VEP also had vision of less than 20/20 (p = 0.037).

CONCLUSION

Visual acuity, color vision and vep are sensitive and sustainable tools which can be implemented in regular screening. Ethambutol toxicity is a real problem and a collaborative approach is necessary to establish screening protocols and prevent ethambutol induced toxic optic neuropathy.

Potential underlying mechanisms of ethambutol induced optic neuropathy: Evidence from in vitro to clinical studies

Ethambutol is an antibiotic widely used for treatment of Mycobacterium species. Although it is safe to use in patients, the ocular toxic impact, including optic neuropathy and retinopathy, can be observed in patients using ethambutol. After discontinuation of the drug, the ocular toxic effects can be reversible in some patients, but some are not. Ethambutol-induced optic neuropathy has been recognized for more than six decades and the prevalence of optic neuropathy from a standard dose of ethambutol has been reported as 0.7-1.29%. Several factors associated with ethambutol-induced optic neuropathy include dosage/duration of drug, the medical conditions of patients such as renal and hepatic dysfunction and preexisting mitochondrial mutations. Currently, there is no specific treatment and prevention of ethambutol-induced optic neuropathy. In addition, the potential underlying mechanisms of ethambutol-induced optic neuropathy is still unclear. Therefore, this review aimed to summarize and discuss evidence from clinical, in vitro, and in vivo studies in order to explore the potential pathophysiology of ethambutol-induced optic neuropathy. Any contradictory findings are also included and discussed. The insights gained from the review will facilitate the discovery of novel approaches for prevention and treatment of optic neuropathy-induced by ethambutol.

Pharmacokinetics and safety of first-line tuberculosis drugs rifampin, isoniazid, ethambutol, and pyrazinamide during pregnancy and postpartum: results from IMPAACT P1026s

Physiological changes during pregnancy may alter the pharmacokinetics (PK) of antituberculosis drugs. The International Maternal Pediatric Adolescent AIDS Clinical Trials Network P1026s was a multicenter, phase IV, observational, prospective PK and safety study of antiretroviral and antituberculosis drugs administered as part of clinical care in pregnant persons living with and without HIV. We assessed the effects of pregnancy on rifampin, isoniazid, ethambutol, and pyrazinamide PK in pregnant and postpartum (PP) persons without HIV treated for drug-susceptible tuberculosis disease. Daily antituberculosis treatment was prescribed following World Health Organization-recommended weight-band dosing guidelines. Steady-state 12-hour PK profiles of rifampin, isoniazid, ethambutol, and pyrazinamide were performed during second trimester (2T), third trimester (3T), and 2-8 of weeks PP. PK parameters were characterized using noncompartmental analysis, and comparisons were made using geometric mean ratios (GMRs) with 90% confidence intervals (CI). Twenty-seven participants were included: 11 African, 9 Asian, 3 Hispanic, and 4 mixed descent. PK data were available for 17, 21, and 14 participants in 2T, 3T, and PP, respectively. Rifampin and pyrazinamide AUC0-24 and C max in pregnancy were comparable to PP with the GMR between 0.80 and 1.25. Compared to PP, isoniazid AUC0-24 was 25% lower and C max was 23% lower in 3T. Ethambutol AUC0-24 was 39% lower in 3T but limited by a low PP sample size. In summary, isoniazid and ethambutol concentrations were lower during pregnancy compared to PP concentrations, while rifampin and pyrazinamide concentrations were similar. However, the median AUC0-24 for rifampin, isoniazid, and pyrazinamide met the therapeutic targets. The clinical impact of lower isoniazid and ethambutol exposure during pregnancy needs to be determined.

Ethambutol-induced optic neuropathy

PURPOSE

A case report of a 40-year-old patient with tuberculosis treated with ethambutol is described. Within six months of starting treatment, there was a painless sudden decline in visual function. Despite the known complications of ethambutol treatment, it was discontinued after another three months.

METHODS

In the case report, we highlight the damage to the dominantly peripheral visual pathways. Using electrophysiological examinations, we showed a significant alteration in the optic nerves. Optical Coherence Tomography (OCT) showed progressive loss of vessel density and nerve fibre layer of retinal ganglion cells. Perimetric examination showed both a central decrease in sensitivity and mainly scotomas in the temporal parts of the visual fields. Although there was improvement in visual fields over time, OCT findings indicated progression of ethambutol-induced optic neuropathy (EON). Magnetic Resonance Imaging confirmed the alteration in the peripheral part of the visual pathway (intraorbital, intracranial parts of optic nerves, chiasma, and optic tracts).

CONCLUSION

Even though EON is not an unknown complication, new cases still occur and, unfortunately, with an irreversible course. Therefore, it is important to draw attention constantly to this complication and to consider it not only in ophthalmologists' surgeries.

Treatment Strategy for Rifampin-Susceptible Tuberculosis

BACKGROUND

Tuberculosis is usually treated with a 6-month rifampin-based regimen. Whether a strategy involving shorter initial treatment may lead to similar outcomes is unclear.

METHODS

In this adaptive, open-label, noninferiority trial, we randomly assigned participants with rifampin-susceptible pulmonary tuberculosis to undergo either standard treatment (rifampin and isoniazid for 24 weeks with pyrazinamide and ethambutol for the first 8 weeks) or a strategy involving initial treatment with an 8-week regimen, extended treatment for persistent clinical disease, monitoring after treatment, and retreatment for relapse. There were four strategy groups with different initial regimens; noninferiority was assessed in the two strategy groups with complete enrollment, which had initial regimens of high-dose rifampin-linezolid and bedaquiline-linezolid (each with isoniazid, pyrazinamide, and ethambutol). The primary outcome was a composite of death, ongoing treatment, or active disease at week 96. The noninferiority margin was 12 percentage points.

RESULTS

Of the 674 participants in the intention-to-treat population, 4 (0.6%) withdrew consent or were lost to follow-up. A primary-outcome event occurred in 7 of the 181 participants (3.9%) in the standard-treatment group, as compared with 21 of the 184 participants (11.4%) in the strategy group with an initial rifampin-linezolid regimen (adjusted difference, 7.4 percentage points; 97.5% confidence interval [CI], 1.7 to 13.2; noninferiority not met) and 11 of the 189 participants (5.8%) in the strategy group with an initial bedaquiline-linezolid regimen (adjusted difference, 0.8 percentage points; 97.5% CI, -3.4 to 5.1; noninferiority met). The mean total duration of treatment was 180 days in the standard-treatment group, 106 days in the rifampin-linezolid strategy group, and 85 days in the bedaquiline-linezolid strategy group. The incidences of grade 3 or 4 adverse events and serious adverse events were similar in the three groups.

CONCLUSIONS

A strategy involving initial treatment with an 8-week bedaquiline-linezolid regimen was noninferior to standard treatment for tuberculosis with respect to clinical outcomes. The strategy was associated with a shorter total duration of treatment and with no evident safety concerns. (Funded by the Singapore National Medical Research Council and others; TRUNCATE-TB ClinicalTrials.gov number, NCT03474198.).

Ocular Toxicity of Ethambutol During Both Intensive and Continuation Phases of Anti-Tubercular Therapy in Children

OBJECTIVE

The study was conducted to evaluate the ocular toxicity of ethambutol given in both intensive and continuation phases of treatment in children with drug-sensitive tuberculosis.

METHODS

A prospective study of 94 eyes from 47 patients receiving an ethambutol-containing regimen was conducted between 1 December, 2018 and 31 August, 2020. Visual acuity, visual field, visual evoked response (VER), contrast sensitivity, colour perception, and retinal nerve fiber layer (RNFL) thickness [using optical coherence tomography (OCT)] were tested for each patient before, during, and after the treatment.

RESULTS

On follow-up, visual acuity, color vision, contrast sensitivity, fundus, and visual fields were not affected in any of the patients. There was no statistically significant increase in the mean latency of the P(100) wave at any point in time. On OCT, no significant loss of mean RNFL thickness was detected.

CONCLUSIONS

Ethambutol is safe to use up to a dose of 20 mg/kg/day throughout the entire course of anti-tubercular therapy in children with drug-sensitive tuberculosis.

Pyrazinamide related prolonged drug-induced liver injury: A case report

RATIONALE

Drug induced liver injury (DILI) is a common side effect causing treatment discontinuation during tuberculosis (TB) treatment, and pyrazinamide (PZA) usually leads to a delayed and prolonged abnormal liver function of the 4 standard anti-tuberculosis regimens. However, a prolonged hepatitis lasting more than 4 months is rarely reported.

PATIENT CONCERNS

A 78-year-old man presented with general weakness and poor appetite on his seventh week of anti-TB treatment for tuberculosis lymphadenitis.

DIAGNOSIS

Drug induced liver injury, PZA-related. NAT2 slow acetylator phenotype was accidentally found during workup of DILI.

INTERVENTION

A liver biopsy was performed and PZA-related DILI was suspected. All anti-TB medications were therefore discontinued.

OUTCOME

After withholding all anti-TB medications for 4 months, the elevations of aminotransferases and hyperbilirubinemia completely resolved. Anti-TB therapy was switched to ethambutol and levofloxacin for 15 months without adverse events. Long-term ultrasound follow-up was performed and cervical lymphadenopathy completely resolved.

CONCLUSION

Our patient presents with PZA related prolonged DILI resolved after drug discontinuation for 4 months. NAT2 slow acetylator phenotype may be related to this condition through unknown mechanisms.

Ocular toxicity among patients taking anti-tubercular treatment

INTRODUCTION

Tuberculosis remains a major public health problem in Nepal and anti-tubercular drugs used for the treatment of pulmonary and extrapulmonary tuberculosis can be associated with ocular toxicity. This prospective study aimed to evaluate the incidence of ocular toxicity among patients receiving anti-tubercular therapy and to assess the change in visual functions and ocular imaging before and after use of anti-tubercular therapy.

MATERIALS AND METHODS

A total of 89 eyes of 45 TB patients taking anti-tubercular therapy were enrolled. Detailed history and examination including best-corrected visual acuity (BCVA), colour vision (Farnsworth D-15t), contrast sensitivity (Pelli-Robson chart), Goldman visual field analysis and spectral domain optical coherence tomography for retinal nerve fibre layer (RNFL) analysis were assessed at baseline and at 6 months after starting anti-tubercular therapy. Visual evoked potential (VEP) was performed in suspected cases.

RESULTS

The mean age of the patients was 29.13±14.00 years and 62.2% were males. The mean weight of the subjects was 54.37±10.36 kg, mean daily dosage of ethambutol was 17.91±1.74 mg/day/kg and mean administration duration was 2.71±1.54 months. The incidence of ocular toxicity was 2.24%. Bilateral retrobulbar optic neuropathy occurred in a 27-year female of 55 kg receiving ethambutol (20 mg/kg/day) for 6 months for Pott's spine. Her best-corrected visual acuity in both eyes was reduced to 6/36 from 6/6 and developed non-specific color vision defect, decreased contrast sensitivity, bilateral cecocentral visual field defect and mean decrease in retinal nerve fibre layer thickness compared to the baseline data. In rest cases, a statistically significant decrease in mean retinal nerve fibre layer thickness in both eyes suggested the evidence of subclinical toxicity.

CONCLUSION

Though less common, ethambutol toxicity can occur in patients under anti-tubercular therapy in the form of retrobulbar optic neuritis. Decreased contrast sensitivity and thinning in the mean retinal nerve fibre layer thickness can be the indicator of subclinical toxicity.

Ethambutol induced toxic optic neuropathy - A retrospective study in a tertiary eye care centre in Southern India

INTRODUCTION

Ethambutol is an antibiotic used as a first line drug in the treatment of tuberculosis and a vision threatening side effect of EMB is ethambutol-induced optic neuropathy (EON). The aim of the study is to create awareness about the potentiality of ethambutol to cause ethambutol-induced optic neuropathy, careful monitoring of dose and patient education.

MATERIALS AND METHODS

A retrospective observational study of 14 patients whose complete Anti- tubercular treatment records could be retrieved were included. Epidemiological data including age, sex, systemic illness were recorded. Duration between optic nerve toxicity , usage of ethambutol and the drug dosage were noted. Best corrected visual acuity, anterior segment examination including pupils, extraocular movements, colour vision, central fields and fundus examination were evaluated. The patients were followed up at one and three month intervals.

RESULTS

Associated systemic illness was found to be a confounding factor for the development of ethambutol-induced optic neuropathy. 57% of patients had diabetes mellitus followed by hypertension (14.2%), renal disease (7.1%). The average daily dose of Ethambutol ingested was 1078.5 mg (21 mg/kg) and this high dose could have been the primary cause for development of ethambutol-induced optic neuropathy. Vision ranged from total blindness to mild visual impairment and poor recovery of vision was noted even after discontinuing ethambutol.

CONCLUSION

Only a minority of patients showed improvement in visual function following discontinuation of ethambutol and the toxicity was found to be dose-dependent. Patients with comorbidities like renal impairment and diabetes mellitus appeared to be at greater risk. Ophthalmological examination before commencing treatment and periodic evaluation thereafter is mandatory.

Optic neuropathy by ethambutol in a patient with multiple sclerosis

We present the clinical case of a patient who developed a toxic optic neuropathy due to ethambutol in the context of a tuberculosis reactivation and who also had a personal history of multiple sclerosis. The objective is to highlight the importance of making a good differential diagnosis of this adverse effect and of knowing its main clinical, campimetric and tomographic manifestations and characteristics. Furthermore, since the reversibility of damage is still discussed in the literature, early diagnosis is essential. For this purpose, it is important to inform the patient of the possible symptoms and to carry out an ophthalmological examination and colour tests before starting treatment to assess whether there is progression.

Drastically Progressive Ethambutol-induced Optic Neuropathy after Withdrawal of Ethambutol: A Case Report and Literature Review

Ethambutol-induced optic neuropathy (EON) is a well-known complication, although low-dose ethambutol seldom causes EON. An 85-year-old man with non-tuberculous mycobacterial lung disease was taking antibiotics, including low-dose ethambutol. On day 85 of treatment, the diagnosis of EON was made. Despite prior discontinuation, his best corrected visual acuity drastically deteriorated from 20/17 (right eye) and 20/20 (left eye) to 20/330 (right eye) and 20/1,000 (left eye) within 3 weeks, and this symptom did not resolve. To our knowledge, there have been no reported cases with drastically progressing and irreversible EON even after the withdrawal of low-dose and short-term ethambutol.

Analysis of structural injury patterns in peripapillary retinal nerve fibre layer and retinal ganglion cell layer in ethambutol-induced optic neuropathy

BACKGROUND

We investigated structural injury patterns in the peripapillary retinal nerve fibre layer (p-RNFL) and ganglion cell inner plexiform layer (GCIPL) caused by ethambutol treatment.

METHODS

Sixty-four patients undergoing ethambutol treatment at Zhejiang Chinese Medicine and Western Medicine Integrated Hospital were recruited. Fourteen (14) exhibited visual dysfunction (abnormal group), and the remaining 50 had no visual dysfunction (subclinical group). The thickness of the p-RNFL, total macular retina layer and GCIPL were measured using Cirrus-HD Optical coherence tomography (Cirrus-HD OCT, Cirrus high-definition optical coherence tomography), and compared with 60 healthy, age-matched controls.

RESULTS

The p-RNFL thickness was similar in both subclinical and control groups. When compared with the control group, p-RNFL thickness in the abnormal group was significantly increased in the inferior and superior quadrants (GEE, P = 0.040, P = 0.010 respectively). In contrast with the subclinical group, p-RNFL thickness in the inferior quadrant was increased in the abnormal group (GEE, P = 0.047). The GCIPL thickness in the inferonasal and inferior sectors was significantly deceased in the subclinical group when compared with controls (GEE, P = 0.028, P = 0.047, respectively). The average and minimum value of GCIPL thickness, and thickness in the superonasal, inferior, inferotemporal, superotemporal and superior sectors were significantly decreased in the abnormal group when compared with controls (GEE, P = 0.016, P = 0.001, P = 0.028, P = 0.010, P = 0.012, P = 0.015, P = 0.010, respectively). The cube average macular thickness (CAMT) in the abnormal group was significantly thinner than controls (GEE, P = 0.027).

CONCLUSIONS

GCIPL measurements using Cirrus-HD OCT detected retinal ganglion cell layer loss following ethambutol treatment, before visual dysfunction occurred.

Ethambutol Optic Neuropathy: Vigilance and Screening, the Keys to Prevent Blindness with the Revised Anti-tuberculous Therapy Regimen

There has been change in the guidelines for the management of tuberculosis in India. The new guidelines advocate the daily use of Ethambutol for both intensive and continuation phase of the treatment. This may be a matter of concern as increased cumulative dose may lead to increase in incidence of toxic optic neuropathy due to ethambutol. Indian Neuro-Ophthalmology Society has taken cognizance of the issue and has come-up with guidelines for prevention and early detection of the toxic optic neuropathy.

Treatment Outcomes after Discontinuation of Ethambutol due to Adverse Events in Mycobacterium avium Complex Lung Disease

BACKGROUND

Long-term administration of ethambutol (EMB) for Mycobacterium avium complex lung disease (MAC-LD) sometimes leads to permanent discontinuation of EMB due to various adverse events. This study aimed to investigate treatment outcomes after discontinuation of EMB.

METHODS

Among patients diagnosed with MAC-LD between January 2001 and December 2014, 508 patients whose treatment was initiated with standard regimen until May 2018 were enrolled at a tertiary referral center in Korea. Of these 508 patients, 60 (11.8%) discontinued EMB due to various adverse effects. Among these 60 patients, treatment outcomes were analyzed for 44 patients by comparing their outcomes with those of matched subjects who received the standard treatment regimen without EMB discontinuation.

RESULTS

The mean age of the 60 patients who discontinued EMB was 64.4 years. Ocular toxicity was the most common cause of discontinuation of EMB (75.0%, 45/60). The mean duration of EMB administration before its discontinuation was 7.0 ± 4.6 months. The treatment failure rate of the 44 patients with EMB discontinuation analyzed for treatment outcome was 29.6%, which was higher than that of the matched patients who received the standard regimen (18.3%), although the difference was not significant (P = 0.095). Of these 44 patients, EMB was substituted with later-generation fluoroquinolone in 23 patients, and the treatment failure rate of these 23 patients was significantly higher than that of the matched patients who received the standard regimen (39.1% vs. 19.3%, P = 0.045).

CONCLUSION

These findings suggest that treatment outcomes are unsatisfactory in patients with MAC-LD who discontinue EMB owing to adverse events. Notably, there was a statistically significant high failure rate in patients who were prescribed fluoroquinolone to replace EMB.

The use of optical coherence tomography for the detection of ocular toxicity by ethambutol

Objectives

To evaluate, through (OCT), alterations in retinal thickness, secondary to use of ethambutol in the treatment of patients with tuberculosis. In addition to studying the use of simpler semiological tools, such as Amsler and Ishihara, in the screening of these cases.

Methods

Thirty patients with ethambutol were recruited from the reference service of tuberculosis treatment at the Federal University of Espírito Santo from May 2015 to July 2016. After clinical history, the following parameters were analyzed; best corrected visual acuity, biomicroscopy, tonometry, photomotor reflex testing, Ishihara test, Amsler’s grid test, color digital retinography and optical coherence tomography with CIRRUS HD-OCT (Humphrey-Zeiss) every 2 months during treatment with ethambutol. They were divided into two groups according to the treatment: (1) standard group, two months of ethambutol; (2) extended group, nine to twelve months of ethambutol.

Results

There was a significant reduction in OCT thickness between the pre and post treatment times in ten eyes of the extended group, mean reduction of 7,8 microns and in seven eyes of the standard group, with an average of 5.57 microns. During the study, a significant reduction of retinal thickness was observed in both groups at two months of treatment, and the delta percentage was higher in those patients who presented reduction of visual acuity and / or change in the Ishihara test.

Conclusion

There was a significant reduction in the thickness of the nerve fiber layer by OCT in the patients studied, being more pronounced in those submitted to the extended treatment regimen. This reduction was observed two months after the start of therapy, and was more significant in the cases that presented changes in the Ishihara test.

Toxicity associated with tuberculosis chemotherapy in the REMoxTB study

BACKGROUND

The incidence and severity of tuberculosis chemotherapy toxicity is poorly characterised. We used data available from patients in the REMoxTB trial to provide an assessment of the risks associated with the standard regimen and two experimental regimens containing moxifloxacin.

METHODS

All grade 3 & 4 adverse events (AEs) and their relationship to treatment for patients who had taken at least one dose of therapy in the REMoxTB clinical trial were recorded. Univariable logistic regression was used to test the relationship of baseline characteristics to the incidence of grade 3 & 4 AEs and significant characteristics (p < 0.10) were incorporated into a multivariable model. The timing of AEs during therapy was analysed in standard therapy and the experimental arms. Logistic regression was used to investigate the relationship between AEs (total and related-only) and microbiological cure on treatment.

RESULTS

In the standard therapy arm 57 (8.9%) of 639 patients experienced ≥1 related AEs with 80 of the total 113 related events (70.8%) occurring in the intensive phase of treatment. Both four-month experimental arms ("isoniazid arm" with moxifloxacin substituted for ethambutol & "ethambutol arm" with moxifloxacin substituted for isoniazid) had a lower total of related grade 3 & 4 AEs than standard therapy (63 & 65 vs 113 AEs). Female gender (adjOR 1.97, 95% CI 0.91-1.83) and HIV-positive status (adjOR 3.33, 95% CI 1.55-7.14) were significantly associated with experiencing ≥1 related AE (p < 0.05) on standard therapy. The most common adverse events on standard therapy related to hepatobiliary, musculoskeletal and metabolic disorders. Patients who experienced ≥1 related AE were more likely to fail treatment or relapse (adjOR 3.11, 95% CI 1.59-6.10, p < 0.001).

CONCLUSIONS

Most AEs considered related to standard therapy occurred in the intensive phase of treatment with female patients and HIV-positive patients demonstrating a significantly higher risk of AEs during treatment. Almost a tenth of standard therapy patients had a significant side effect, whereas both experimental arms recorded a lower incidence of toxicity. That patients with one or more AE are more likely to fail treatment suggests that treatment outcomes could be improved by identifying such patients through targeted monitoring.

The rare ethambutol-induced optic neuropathy: A case-report and literature review

RATIONALE

Ethambutol-induced optic neuropathy (EON) is a well-known complication that results from the use of ethambutol. The ocular manifestations of EON include painless loss of central vision and cecocentral scotomas in the visual field.

PATIENT CONCERNS

A 75-year-old Chinese Han man suffered from this rare ocular disorder because he took ethambutol for about 8 months.

DIAGNOSES

He was diagnosed as EON based on series of ophthalmic examinations performed.

INTERVENTIONS

Since he has stopped taking this drug for 3 months, we just offered some neurotrophic agents to him.

OUTCOMES

One month later, he came back for return visit. The ophthalmic examinations indicated recovery of the visual function very well.

LESSONS

The EON is a reversible optic neuropathy if the ocular toxicity is monitored closely among the tuberculosis patients that take ethambutol.

Ethambutol induces testicular damage and decreases the sperm functional competence in Swiss albino mice

The present study reports the effect of ethambutol (EMB) on testicular function. Prepubertal and adult male Swiss albino mice were treated with 40, 80, 160mg/kg body weight of EMB, intraperitoneally, every alternate day for 4 weeks. After 2 weeks gap, mice were sacrificed to collect caudal spermatozoa. EMB treatment resulted in a dose-dependent decrease in the testicular weight, sperm count and motility while the percentage of sperm with head abnormalities, immature chromatin (P<0.001) and DNA damage increased (P<0.01). In addition, EMB treatment resulted in significant depletion of glutathione (P<0.05-P<0.01) and histopathological abnormalities such as large cells, vacuolation of tubules and isolated colonies of spermatogenic cells were observed. Oct4, 17β-Hsd and c-Kit mRNA was marginally elevated in EMB treated testes at the highest dose studied. In conclusion, the result of the present study indicates that EMB has adverse effect on testicular function and impairs the sperm functional competence.

Ethambutol toxicity manifesting as acute onset psychosis

Ethambutol is commonly used for the treatment of tuberculous and atypical mycobacterial infection. Central nervous system (CNS) toxicity other than optic neuropathy is not widely reported. A 40-year-old man with advanced HIV infection and Mycobacterium avium complex infection experienced rapid cognitive decline after commencement of ethambutol, and symptoms fully resolved with cessation.

Ameliorative Effects of Kolaviron, a Biflavonoid Fraction from Garcinia Kola Seed, on Hepato-renal Toxicity of Anti-tuberculosis Drugs in Wistar Rats

BACKGROUND

Tuberculosis (TB) is an infectious disease of international health priority. The combination of anti-TB drugs (4-Tabs)- isoniazid (INH), rifampicin (RIF), pyrazinamide (PZA) and ethambutol (ETB) are effective in the management of the disease, however, their toxic effect is a major concern.

PURPOSE

The study was designed to evaluate the toxicity of anti-TB drugs in male Wistar rats and possible ameliorative effects of kolaviron (KV), a biflavonoid from Garcinia kola seeds.

METHODS

Twenty-eight rats were assigned into four groups; Group 1 (Control) received corn oil, Group 2 (4-Tabs) received therapeutic doses of INH (5 mg/kg), RIF (10 mg/kg), PZA (15 mg/kg) and ETB (15 mg/kg) in combination, Group 3 (4-Tabs + KV) received INH, RIF, PZA, ETB and KV (200 mg/kg) and Group 4 (KV) received KV (200 mg/kg) by oral gavage three times per week for 8 consecutive weeks.

RESULTS

Administration of 4-Tabs caused oxidative stress resulting in significant (p = 0.031, 0.027) increase in malondialdehyde levels in the liver and kidney of rats by 101% and 34%, respectively. Also, 4-Tabs caused significant (p = 0.023-0.035) elevation of serum alanine and aspartate aminotransferases by 41% and 48%, creatinine by 252% and total bilirubin by 89%, respectively. In contrast, hepatic and renal antioxidant indices- reduced glutathione, glutathione peroxidase, glutathione-s-transferase and superoxide dismutase were significantly (p = 0.028-0.039) decreased in 4-Tabs-treated rats. Co-administration of KV with 4-Tabs significantly restored the antioxidant parameters and biochemical indices to near normal.

CONCLUSION

These findings suggest that anti-TB drugs elicit oxidative damage in liver and kidney of rats while KV protects against the adverse effects via antioxidative mechanism.

From a fish tank injury to hospital haemodialysis: the serious consequences of drug interactions

We present the case of a 68-year-old man admitted to hospital with severe acute kidney injury secondary to statin-induced rhabdomyolysis. Five weeks previously, the patient started a course of clarithromycin for infection of a finger wound with Mycobacterium marinum. His current medications included simvastatin, which he continued along with clarithromycin. The severity of the acute kidney injury necessitated initial continuous venovenous haemofiltration followed by 12 haemodialysis sessions before a spontaneous improvement in renal function occurred. Statins are widely prescribed and we report this case to encourage increased vigilance in avoiding drug interactions known to increase the risk of statin-induced myopathy, including macrolide antibiotics, calcium channel antagonists and amiodarone. The authors would also like to highlight recent guidance on atorvastatin as the statin of choice in patients with chronic kidney disease, and of the need for dose adjustment in those with an estimated glomerular filtration rate less than 30 mLs/min/1.73 m².

Drug-induced hepatotoxicity of anti-tuberculosis drugs and their serum levels

The correlation between serum anti-tuberculosis (TB) drug levels and the drug-induced hepatotoxicity (DIH) remains unclear. The purpose of this study was to investigate whether anti-TB DIH is associated with basal serum drug levels. Serum peak levels of isoniazid (INH), rifampicin (RMP), pyrazinamide (PZA), and ethambutol (EMB) were analyzed in blood samples 2 hr after the administration of anti-TB medication. Anti-TB DIH and mild liver function test abnormality were diagnosed on the basis of laboratory and clinical criteria. Serum anti-TB drug levels and other clinical factors were compared between the hepatotoxicity and non-hepatotoxicity groups. A total of 195 TB patients were included in the study, and the data were analyzed retrospectively. Seventeen (8.7%) of the 195 patients showed hepatotoxicity, and the mean aspartate aminotransferase/alanine aminotransferase levels in the hepatotoxicity group were 249/249 IU/L, respectively. Among the 17 patients with hepatotoxicity, 12 showed anti-TB DIH. Ten patients showed PZA-related hepatotoxicity and 2 showed INH- or RMP-related hepatotoxicity. However, intergroup differences in the serum levels of the 4 anti-TB drugs were not statistically significant. Basal serum drug concentration was not associated with the risk anti-TB DIH in patients being treated with the currently recommended doses of first-line anti-TB treatment drugs.

[Hypothermia due to anti-tuberculosis drugs: first case]

Hypothermia - an adverse reaction of drug use potentially severe - requires an early diagnosis and an adapted management. We report the first case, to our knowledge of hypothermia due to anti-tuberculosis drugs.

Profile of adverse drug reactions in drug resistant tuberculosis from Punjab

OBJECTIVE

The aim of the study was to elucidate the profile of adverse drug reactions (ADRs) associated with second-line anti-tubercular treatment for drug-resistant tuberculosis.

MATERIAL AND METHODS

ADR profile of diagnosed drug-resistant tuberculosis cases on supervised second-line anti-tubercular drug regimen under Programmatic Management of Drug-resistant Tuberculosis under Revised National Tuberculosis Control Programme, were studied over two years' period. Adverse reactions were categorised into mild, moderate and severe types with subsequent systematic data-analysis.

RESULTS

Out of total 207 patients in the study, 81.16% reported with adverse drug reactions. Out of total 195 adverse events, 63.58%, 18.46% and 17.94% were of mild, moderate and severe types respectively. Gastrointestinal events, hepatitis, hearing impairment, arthralgia, psychosis, hypothyroidism, visual disturbances, giddiness, peripheral neuropathy, skin reactions, swelling or pain at injection site, anorexia and sleep disturbances were important amongst these. High proportion of drug and/or alcohol abuse was an important observation. The offending drug(s) had to be terminated in 12.08% of the patients.

CONCLUSION

Early detection, management and pharmaco-vigilance reporting of ADRs remain key factors in the management of drug-resistant tuberculosis with remarkable relevance of the need for early diagnosis and treatment of 'drug-sensitive tuberculosis', to prevent emergence of drug-resistant tuberculosis.

The incidence of liver injury in Uyghur patients treated for TB in Xinjiang Uyghur autonomous region, China, and its association with hepatic enzyme polymorphisms nat2, cyp2e1, gstm1 and gstt1

Background and Objective

Of three first-line anti-tuberculosis (anti-TB) drugs, isoniazid is most commonly associated with hepatotoxicity. Differences in INH-induced toxicity have been attributed to genetic variability at several loci, NAT2, CYP2E1, GSTM1and GSTT1, that code for drug-metabolizing enzymes. This study evaluated whether the polymorphisms in these enzymes were associated with an increased risk of anti-TB drug-induced hepatitis in patients and could potentially be used to identify patients at risk of liver injury.

Methods and Design

In a cross-sectional study, 2244 tuberculosis patients were assessed two months after the start of treatment. Anti-TB drug-induced liver injury (ATLI) was defined as an ALT, AST or bilirubin value more than twice the upper limit of normal. NAT2, CYP2E1, GSTM1 and GSTT1 genotypes were determined using the PCR/ligase detection reaction assays.

Results

2244 patients were evaluated, there were 89 cases of ATLI, a prevalence of 4% 9 patients (0.4%) had ALT levels more than 5 times the upper limit of normal. The prevalence of ATLI was greater among men than women, and there was a weak association with NAT2*5 genotypes, with ATLI more common among patients with the NAT2*5*CT genotype. The sensitivity of the CT genotype for identifying patients with ATLI was 42% and the positive predictive value 5.9%. CT ATLI was more common among slow acetylators (prevalence ratio 2.0 (95% CI 0.95,4.20) )compared to rapid acetylators. There was no evidence that ATLI was associated with CYP2E1 RsaIc1/c1genotype, CYP2E1 RsaIc1/c2 or c2/c2 genotypes, or GSTM1/GSTT1 null genotypes.

Conclusions

In Xinjiang Uyghur TB patients, liver injury was associated with the genetic variant NAT2*5, however the genetic markers studied are unlikely to be useful for screening patients due to the low sensitivity and low positive predictive values for identifying persons at risk of liver injury.

L’intérêt de l’accoutumance aux antituberculeux majeurs

Les réactions d’ hypersensibilité aux antituberculeux sont relativement rares et graves par leur caractère imprévisible, elles conduisent généralement à l'arrêt ou au changement thérapeutique. Nous rapportons un cas d'hypersensibilité à trois antibacillaires majeurs (Isoniazide, Pyrazinamide, Ethombutol). Une accoutumance orale à ces trois médicaments a été réalisée permettant à la patiente de bénéficier d'un traitement antibacillaire optimal.

Eczematous-type multiple drug allergy from isoniazid and ethambutol with positive patch test results

Multiple drug allergy (MDA) is characterized by hypersensitivity to 2 or more chemically unrelated drugs. Multiple drug allergy from simultaneous use of antituberculosis drugs is a rare phenomenon that mainly presents as an urticarial or maculopapular eruption. This case report describes a 58-year-old man who developed a generalized eczematous eruption during the sixth week of oral therapy with 4 antituberculosis drugs-isoniazid, ethambutol, rifampicin, and morphazinamide-for treatment of suspected pleural tuberculosis. The eruption resolved after treatment with systemic corticosteroids and cessation of isoniazid and ethambutol. During a lesion-free period 6 months after cessation of the corticosteroids, patch testing with serial dilutions of isoniazid and ethambutol revealed positive reactions; irritant patch test reactions were excluded by testing with graded concentrations of each drug. The patient avoided the causative drugs and reported no new eruptions at 1-year follow-up. It is important for dermatologists to consider the value of patch testing in determining the causative drugs in suspected cases of eczematous-type MDA.

[A study of adverse drug reactions in the treatment of pulmonary Mycobacterium avium complex disease]

OBJECTIVES

Adverse drug reactions interfere with the standard treatment of pulmonary Mycobacterium avium complex (MAC) disease; however, few studies have investigated this issue. We studied adverse drug reactions in the treatment of pulmonary MAC disease.

SUBJECTS

We retrospectively examined 74 patients who underwent treatment for pulmonary MAC disease in our hospital between January 2001 and December 2009. These patients had received treatment with rifampicin, ethambutol (EB), and clarithromycin. We analyzed the adverse drug reactions seen in these patients.

RESULTS

Twenty-two patients developed one or more adverse drug reactions that led to treatment discontinuation or change in medication, whereas 52 patients did not experience any adverse reactions. The incidence rate of adverse reactions was 29.7%. The adverse drug reactions included visual impairment in 9 patients, liver function disorder in 2, skin eruption in 5, and fever in 5. In most of the cases, the standard treatment could not be continued.

DISCUSSION

Visual impairment associated with EB was the most common adverse drug reaction, and it led to the discontinuation of EB, and thus the standard treatment. Additionally, in case of other adverse drug reactions, it was difficult to find appropriate replacements for the causative drugs. Further investigations are required to establish a standard policy for the management of adverse drug reactions that can lead to the discontinuation of chemotherapy.

[Therapeutic approach in a case of allergic reaction to antituberculosis drugs -- a case report]

Medicaton used to treat tuberculosis is responsible for numerous side effects that have a major impact on patient's health, with a negative influence on the quality of life. Patients of all ages must be trained in order to recognize all the adverse effects and the undesirable reactions produced by antituberculosis medication. We report the case of a 24-year-old woman with generalized psoriasis and psoriatic arthropathy who was treated against tuberculosis. After 7 days of treatment with isoniazid, rifampicin, ethambutol and pyrazinamid she had severe allergic reaction with generalized pruritus and rash which were difficult to control with antiallergic treatment.

CONCLUSIONS

Particular to this case is the absence in patient's history of the allergic reactions to medication. The re-establishment of treatment of tuberculosis was done by clinical trials and the patient had responded to only three drugs: isoniazid, rifampicin and ofloxacin, so the patient received an individual treatment due to adverse reactions to tuberculosis medications.

[Directly observed treatment for tuberculosis in a Buenos Aires City hospital]

The outcomes of directly observed therapy of tuberculosis (DOT) between 1/1/1979 and 12/31/2009 were analyzed. Results obtained in the 1979-1999 period were compared with those achieved in the 2000-2009 period. In a Buenos Aires City hospital, 582 HIV negative TB patients received rifampin, isoniazid, pyrazinamide and ethambutol or streptomycin in the initial stage, followed by a second stage where patients were included in two groups: G1 composed by 424 patients (period 1/1/1979-12/31/1999) who received either rifampin and isoniazid or rifampin and streptomicin twice a week, and G2, with 158 patients (period 1/1/2000-12/31/2009) who received either rifampin and isoniazid twice or three times a week. National and Buenos Aires City TB Control Programs recommendations were followed. Patients who underwent DOT had higher completeness rates than those included in self-administered therapy (82.8% vs. 48.7%), (p <0.0001). Mean age: 36.3 ± 15.3 years, males: 63.1% and 69.4% were Argentine citizens. A 8.9% had been previously treated, 6.1% had co-morbidities. A 70.6% of pulmonary cases was bacteriologically confirmed, 82.8% of them completed the treatment, while 11.5% defaulted. Adverse effects to antituberculosis drugs were observed in 9.5% of cases; male patients showed higher rates of non adherence. G2 had a lower proportion of native people (48.7% vs. 77.1%), (p = 0.0001), higher frequency of co-morbidities (10.7% vs. 4.4%), (p = 0.005), of bacteriologically confirmed pulmonary cases (95% vs. 87%), (p = 0.02) and more adverse effects than G1 (17% vs. 6.6%), (p = 0.0001). In coincidence with other experiences, this work shows high treatment success rates in patients treated under DOT strategy.

Efficacy and safety of a 4-drug fixed-dose combination regimen compared with separate drugs for treatment of pulmonary tuberculosis: the Study C randomized controlled trial

CONTEXT

Fixed-dose combinations (FDCs) of drugs for treatment of tuberculosis have been advocated to prevent the emergence of drug resistance.

OBJECTIVE

To assess the efficacy and safety of a 4-drug FDC for the treatment of tuberculosis.

DESIGN, SETTING, AND PATIENTS

The Study C trial, a parallel-group, open-label, noninferiority, randomized controlled trial conducted in 11 sites in Africa, Asia, and Latin America between 2003 and 2008. Patients were 1585 adults with newly diagnosed smear-positive pulmonary tuberculosis.

INTERVENTIONS

Patients were randomized to receive daily treatment with 4 drugs (rifampicin, isoniazid, pyrazinamide, ethambutol) given as an FDC (n = 798 patients) or separately (n = 787) in the 8-week intensive phase of treatment.

MAIN OUTCOME MEASURE

Favorable treatment outcome, defined as negative culture result at 18 months post randomization and not having already been classified as unfavorable. Noninferiority was dependent on consistent results from a per-protocol and modified intention-to-treat analysis, using 2 different models for the latter, classifying all changes of treatment or refusal to continue treatment (eg, bacteriological failure/relapse, adverse event, default, drug resistance) as unfavorable (model 1) and classifying changes of treatment for reasons other than therapeutic outcomes according to their 18-month bacteriological outcome if available (post hoc model 2). The prespecified noninferiority margin was 4%.

RESULTS

In the per-protocol analysis, 555 of 591 patients (93.9%) had a favorable outcome in the FDC group vs 548 of 579 (94.6%) in the separate-drugs group (risk difference, -0.7% [90% confidence interval {CI}, -3.0% to 1.5%]). In the model 1 analysis, 570 of 684 patients (83.3%) had a favorable outcome in the FDC group vs 563 of 664 (84.8%) in the separate-drugs group (risk difference, -1.5% [90% CI, -4.7% to 1.8%]). In the post hoc model 2 analysis, 591 of 658 patients (89.8%) in the FDC group and 589 of 647 (91.0%) in the separate-drugs group had a favorable outcome (risk difference, -1.2% [90% CI, -3.9% to 1.5%]). Adverse events related to trial drugs were similarly distributed among treatment groups.

CONCLUSIONS

Compared with a regimen of separately administered drugs, a 4-drug FDC regimen for treatment of tuberculosis satisfied prespecified noninferiority criteria in 2 of 3 analyses. Although the results do not demonstrate full noninferiority of the FDCs compared with single drugs given separately using the strict definition applied in this trial, use of FDCs is preferred because of potential advantages associated with the administration of FDCs compared with separate-drug formulations.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00216333.

Visual fields in neuro-ophthalmology

Visual field assessment is important in the evaluation of lesions involving the visual pathways and should be performed at baseline and periodically in the follow-up. Standard automated perimetry has been shown to be adequate in neuro-ophthalmic practise and is now the technique of choice for a majority of practitioners. Goldman kinetic visual fields are useful for patients with severe visual and neurologic deficits and patients with peripheral visual field defects. Visual fields are useful in monitoring progression or recurrence of disease and guide treatment for conditions such as idiopathic intracranial hypertension (IIH), optic neuropathy from multiple sclerosis, pituitary adenomas, and other sellar lesions. They are used as screening tools for toxic optic neuropathy from medications such as ethambutol and vigabatrin. Visual field defects can adversely affect activities of daily living such as personal hygiene, reading, and driving and should be taken into consideration when planning rehabilitation strategies. Visual field testing must be performed in all patients with lesions of the visual pathway.

Assessment of protective role of polyherbal preparation, Livina, against anti-tubercular drug induced liver dysfunction

The present study evaluated the possible protective role of Livina (a polyherbal preparation) against anti-tubercular therapy (ATT)-induced liver dysfunction in patients of pulmonary tuberculosis. Patients were given intensive phase treatment with 4-drugs (rifampicin, INH, pyrazinamide and ethambutol) used for anti-tubercular therapy for 2 months, followed by a 4-month continuous phase treatment with 2 drugs (rifampicin and INH) under clinical advice and supervision. Both qualitative and quantitative measures of liver function were assessed, at different time intervals, before and after ATT. Analysis of data showed that the incidence of qualitative manifestations of liver dysfunction were greater in the placebo treated group as compared to the test drug group. None of the patients of either group showed clinical jaundice. Most signific changes ant were observed in the SGOT and SGPT levels in the placebo group, wherein the levels of both enzymes were higher at 4 and 8 weeks post-ATT, as compared to the respective baseline (0 week) values. When Livina (2 capsules twice daily) was given with ATT drugs, incidence of qualitative manifestation of liver dysfunction was insignificant and SGOT and SGPT levels were also significantly lower than the placebo+AITT drugs treated group. These results indicate that the test drug (Livina) was efficacious, against ATT-induced hepatic dysfunction in patients of pulmonary tuberculosis.

[Apoptosis-inducing action of antituberculosis drugs of the main group in vitro]

The influence of the main antituberculosis drugs (isoniazid, rifampicin, ethambutol) on in vitro apoptosis of peripheral blood lymphocytes from patients with pulmonary tuberculosis was researched. It was shown that all the investigated drugs induced apoptotic death of the lymphocytes in vitro, that could result in disturbance of antigen-specific response formation in pulmonary tuberculosis.

[EVALUATION OF THE EFFICIENCY OF TREATMENT AND THE CHOICE OF CONTROL COMPUTED TOMOGRAPHY TIME IN CHILDREN WITH MINOR FORMS OF INTRATHORACIC TUBERCULOSIS]

Three chemotherapy regimens (Group 1: 2HRZ/4HR, n = 31; Group 2: 2HRZ/4HZ, n = 33; Group 3: 6HR, n = 33) were comparatively assessed in children with minor forms of intrathoracic tuberculosis diagnosed by the computed tomography (CT). The leading criteria for therapeutic effectiveness were regression of intoxication symptoms and changes in the CT pattern. The results of treatment were equal in all the groups. With the 6HR regimen, varying unavoidable adverse reactions were 4.3-fold less frequently (3.0 ± 3.0% and 12.5 ± 4.1%, respectively; p = 0.25). CT pattern changes by months 2-3 and 6 of therapy were compared. Single control CT investigation by 6 months of therapy was optimal. Additional CT study at 2-3 months of therapy reflected positive changes in most cases, but failed to affect treatment policy.

Ethambutol Neuroretinopathy

OBJECTIVE

To describe the clinical features of ethambutol neuroretinopathy.

DESIGN

Case report and meta-analysis of the literature.

PARTICIPANTS

A patient with clinical and electrophysiological findings suggestive of ethambutol neuroretinopathy.

TESTING

Electroretinogram, electro-oculogram and visual fields.

MAIN OUTCOME MEASURE

Clinical and electrophysiological findings.

RESULTS

101 cases were reviewed, retinal findings include retinal pigment epithelial changes, macular edema, flame-shaped hemorrhages. Electroretinogram findings include decreased amplitude and abnormal wave pattern in full field ERG, multifocal or pattern ERG and electro-oculogram findings include abnormal Arden ratio.

CONCLUSIONS

Clinical, electrophysiological and in vitro studies support the toxic effect of ethambutol on the retina. Therefore ethambutol ocular toxicity may be a neuroretinopathy.