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PubMed1996

Roxithromycin alone and in combination with either ethambutol or levofloxacin for disseminated Mycobacterium avium infections in beige mice.

Roxithromycin alone reduced the level of bacteremia caused by Mycobacterium avium complex liver and splenic infection (in CFU per gram) of beige mice and mortality compared with untreated controls (P < 0.05). Roxithromycin plus ethambutol resulted in a significant reduction in the number of bacteria in splenic tissue compared with those in control splenic tissues of mice and mice treated with roxithromycin alone and ethambutol alone. Roxithromycin plus levofloxacin was not better than roxithromycin alone. Roxithromycin has in vivo activity against M. avium complex strains, and pilot studies with humans may be considered.

Animals↗
PubMed2004

Development of a liposome formulation of ethambutol.

A liposomal formulation capable of encapsulating 76 to 92% of the antimycobacterial drug ethambutol and showing prolonged in vitro release kinetics is described. In vitro efficacy is equivalent to that of the free drug, suggesting that encapsulation of ethambutol has the potential to shorten the current regimens for tuberculosis.

Antitubercular Agents↗
PubMed1998

Flow cytometric testing of susceptibilities of Mycobacterium tuberculosis isolates to ethambutol, isoniazid, and rifampin in 24 hours.

Susceptibility testing of Mycobacterium tuberculosis is seriously limited by the time required to obtain results. We show that susceptibility testing of clinical isolates of M. tuberculosis can be accomplished rapidly with acceptable accuracy by using flow cytometry. The susceptibilities of 35 clinical isolates of M. tuberculosis to various concentrations of isoniazid, rifampin, and ethambutol were tested by the agar proportion method and by flow cytometry. Agreement between the results from the two methods was 95, 92, and 83% for isoniazid, ethambutol, and rifampin, respectively. Only 11 discrepancies were detected among 155 total tests. The results of flow cytometric susceptibility tests were available within 24 h of inoculation of drug-containing medium, while the proportion method required 3 weeks to complete. The flow cytometric method is also simple to perform.

Agar↗
PubMed1984

Controlled trial of rifampicin and ethambutol in Crohn's disease.

We pursued the possibility that Mycobacterium kansasii might be an aetiological agent in Crohn's disease by carrying out a trial of treatment with antimycobacterial drugs. Twenty seven patients with Crohn's disease took part in a two year randomised double blind, crossover, controlled trial of rifampicin plus ethambutol against placebo. Fourteen patients completed the trial; four required an operation; five were withdrawn as poor compliers, and four because of adverse effects. There was no significant difference in response to the active drugs compared with placebo when expressed in terms of a Crohn's disease activity index or any clinical indicator of disease activity. There was no suggestion that any subgroup of patients - for example, different regions of bowel affected or previous operation - were favourably affected by the drugs. There was no consistent pattern of change in prednisolone requirements although eight patients on long term sulphasalazine had a significant reduction in their plasma sulphapyridine concentrations during the active treatment period. A significant reduction in total white blood count and an increase in plasma ALT were seen during active therapy. The results of the study do not suggest that rifampicin and ethambutol have a role to play in the treatment of Crohn's disease.

Adult↗
PubMed1985

A case of ocular toxicity to ethambutol--an idiosyncratic reaction?

Optic neuritis, a well known adverse effect of ethambutol, is related to the dose and duration of the therapy. The patient described here developed rapidly progressive deterioration of vision after only 3 days of treatment with ethambutol. Such a case has not been reported before and it is suspected that this was an idiosyncratic reaction.

Adult↗
PubMed1994

Oral desensitization to rifampin and ethambutol in mycobacterial disease.

The incidence of disease caused by Mycobacterium tuberculosis (including drug-resistant strains) and M. avium complex (MAC) is increasing. Hypersensitivity reactions to antimycobacterial agents are relatively uncommon, but when they occur they may result in cessation of therapeutic medications. We report our experience with rapid oral desensitization to ethambutol and rifampin in a group of 10 patients with mycobacterial disease who had experienced cutaneous hypersensitivity reactions to these drugs. An adaptation of the rapid oral desensitization protocol for penicillin was used, with the dosing intervals increased to account for the different kinetics of these drugs. Adverse reactions were few and easily treated without necessitating cessation of therapy. We conclude that oral desensitization to rifampin and ethambutol by our protocol is safe and effective, allowing these patients to proceed with an optimal antimycobacterial regimen.

Administration, Oral↗
PubMed2005

High hepatotoxicity of pyrazinamide and ethambutol for treatment of latent tuberculosis.

Pyrazinamide (PZA) combined with either ethambutol (EMB) or a fluoroquinolone for 6-12 months is one of the treatments recommended for latent tuberculosis infection (LTBI) in contacts exposed to multidrug-resistant tuberculosis (MDR-TB). The aim of the present study was to describe the side effects related to combined PZA and EMB treatment given for LTBI, in contacts previously exposed to MDR-TB. In total, 12 consecutive contacts, all of African origin and aged 38+/-5 yrs, were treated with daily PZA (23+/-4 mg.kg(-1)) and EMB (17+/-4 mg.kg(-1)) at Geneva University Hospital outpatient clinic (Switzerland), as a result of contact-tracing procedures for two patients with contagious MDR-TB. Clinical status and liver function tests (aspartate aminotransferase (ALAT) and alanine aminotransferase (ASAT)) were monitored monthly. In seven cases (58%) treatment was discontinued after a median of 119 days, due to hepatic toxicity in six cases (ALAT or ASAT elevation more than four times the upper normal limit), and gastrointestinal symptoms in one case. In conclusion, combined pyrazinamide and ethambutol for latent tuberculosis infection may be associated with a high risk of hepatic toxicity, and warrants close monitoring. There is clearly a need for alternative preventive treatments for contacts exposed to multidrug-resistant tuberculosis.

Adult↗
PubMed2005

Fluorescent phospholipid analogs as microscopic probes for detection of the mycolic acid-containing layer in Corynebacterium glutamicum: detecting alterations in the mycolic acid-containing layer following ethambutol treatment.

Corynebacterium glutamicum belongs to the mycolic acid-containing actinomycetes, which also include Mycobacterium, Nocardia, and Rhodococcus. The cells of this group possess a cell wall with a thick outer layer composed primarily of mycolic acid, which functions as a permeability barrier. To investigate the mechanism of mycolic acid-containing layer (mycolate layer) formation, we have developed a fluorescence microscopic technique detecting the mycolate layer in situ. The staining specificity of fluorescence-labeled phospholipid analogs was determined by simultaneous staining with the hydrophobic fluorescent dye Nile Red and peptidoglycan-staining fluorescence-conjugated vancomycin. We found that fluorescence-labeled phospholipid analogs preferentially stain the mycolate layer. Using this technique, we observed the effect of the anti-mycobacterial drug ethambutol on C. glutamicum mycolate-layer formation. Ethambutol interfered specifically with mycolate-layer formation on the division planes and cell poles, while the side-wall mycolate layer was not severely affected. This indicates that mycolate-layer formation occurs mainly on division planes and cell poles in C. glutamicum, where the peptidoglycan layer is actively synthesized.

Anti-Infective Agents↗
PubMed2003

Treatment of Mycobacterium avium-intracellulare complex lung disease with a macrolide, ethambutol, and clofazimine.

BACKGROUND: Mycobacterium avium-intracellulare (MAC) causes progressive lung disease. Recommended treatment regimens include a macrolide and a rifamycin, but drug intolerance and relapse after treatment is completed often limit successful therapy. METHODS: Consecutive individuals referred for treatment of MAC lung disease were treated with a regimen that included either clarithromycin, 500 mg bid, or azithromycin, 250 mg/d, on weekdays; ethambutol, 15 mg/kg/d; and clofazimine, 100 mg/d. The intention was to treat patients for a minimum of 12 months. The diagnosis of MAC lung disease was confirmed by multiple positive sputum culture findings in patients with typical symptoms and radiologic findings. RESULTS: Thirty patients (27 women and 3 men; mean age, 70 +/- 9.4 years [SD]) were treated. A total of 22 of the patients reported adverse effects from clarithromycin or azithromycin. Intolerance of clarithromycin resulted in the withdrawal of four patients before sputum conversion. The remaining patients continued treatment for an average of 10 months, and sputum findings converted to negative in all 26 patients (87%). One patient died of unrelated causes while still receiving therapy, and five patients (19%) relapsed an average of 17 months after treatment was completed. CONCLUSIONS: Treatment with a macrolide, ethambutol, and clofazimine was successful in 20 of 30 patients (67%) with MAC lung disease and is a reasonable alternative to rifamycin-containing regimens.

Aged↗
PubMed1990

Treatment of disseminated Mycobacterium avium complex infection in AIDS with amikacin, ethambutol, rifampin, and ciprofloxacin. California Collaborative Treatment Group.

OBJECTIVE: To determine the efficacy of combination drug therapy for disseminated Mycobacterium avium complex infection in patients with the acquired immunodeficiency syndrome (AIDS). DESIGN: Prospective, nonrandomized, before-after comparison. SETTING: Outpatient clinics at three university medical centers. PATIENTS: Seventeen patients with at least two consecutive blood cultures positive for M. avium complex who had not been previously treated with antituberculous medications. Fifteen of the seventeen patients completed at least 4 weeks of treatment. INTERVENTION: Patients received daily intravenous amikacin (7.5 mg/kg body weight) for the first 4 weeks plus the following oral medications for at least 12 weeks: ciprofloxacin, 750 mg twice daily; ethambutol, 1000 mg daily; and rifampin, 600 mg daily. MEASUREMENTS AND MAIN RESULTS: The baseline geometric mean colony count from blood cultures decreased from 537/mL to 14/mL (P less than 0.001) after 4 weeks of therapy. The microbiologic suppression was sustained while on treatment and was associated with a decrease in systemic symptoms related to M. avium complex infection. Premature withdrawal from treatment (less than 12 weeks) occurred in 7 of 17 patients. The commonest reasons for early withdrawal were gastrointestinal intolerance and hepatic toxicity. CONCLUSIONS: Mycobacterial load and systemic symptoms in patients with AIDS and disseminated M. avium complex infection can be effectively reduced by a regimen containing amikacin, ethambutol, rifampin, and ciprofloxacin.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Treatment of Mycobacterium avium complex bacteremia in AIDS with a four-drug oral regimen. Rifampin, ethambutol, clofazimine, and ciprofloxacin. The California Collaborative Treatment Group.

OBJECTIVE: To determine the quantitative microbiologic response and the clinical response of patients with Mycobacterium avium complex bacteremia and AIDS to an oral antimycobacterial regimen. DESIGN: A phase II, multicenter clinical trial. SETTING: Four university-affiliated medical centers. PATIENTS: Forty-one patients with HIV infection who had at least two consecutive blood cultures positive for M. avium complex and who had not received previous antimycobacterial therapy were enrolled in the study. Thirty-one patients were evaluable with regard to the efficacy of the oral regimen. INTERVENTIONS: Patients received a combination of orally administered rifampin (600 mg), ethambutol (15 mg/kg body weight), clofazimine (100 mg once daily), and ciprofloxacin (750 mg twice daily) for 12 weeks. Parenterally administered amikacin, 7.5 mg/kg daily for 4 weeks after the first 4 weeks of oral therapy, was used at the discretion of the individual investigator. MEASUREMENTS: Clinical symptoms, Karnofsky scores, and adverse events were monitored. Colony counts for M. avium complex were determined. MAIN RESULTS: The mean logarithmic (log) baseline colony count decreased from 2.1 to 0.7 after 4 weeks of oral therapy (P less than 0.001). Suppression of bacteremia was sustained throughout therapy. Thirteen patients (42%) became culture negative during therapy. The mean duration of treatment was 9.7 weeks. Nineteen evaluable patients (61%) completed 12 weeks of therapy. Adverse reactions to one or more agents were common. CONCLUSIONS: A rapid reduction in symptoms and bacteremia can be achieved as early as week 2 of therapy using an oral regimen of rifampin, ethambutol, clofazimine, and ciprofloxacin. Colony counts rose dramatically after therapy was discontinued, suggesting that more prolonged periods of therapy are necessary to eradicate systemic infection.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Biochemical mechanism of combined effect of ethambutol and sparfloxacin against Mycobacterium smegmatis.

M. smegmatis cells grown in the presence of combination of ethambutol (EMB) and sparfloxacin (SPX) had decreased level of total cellular lipids as compared to control as well as cells grown in the presence of sub-inhibitory concentration (MIC50) of individual drugs. Amongst various phospholipids analyzed, maximum decrease was observed in the content of phosphatidylinositolmannosides (PIMs) of the cells grown in combination of EMB and SPX. In contrast, the subcellular distribution of phospholipids revealed a significant increase in PIMs content of both cell wall and cell membrane of the cells grown in the presence of combination of drugs as compared to control as well as individual drugs. Mycolic acids of M. smegmatis cells were found to be main targets as combination of drugs resulted in significant decrease in total cellular as well as cell wall mycolic acids as compared to control and individual drugs. Changed lipid composition of M. smegmatis cells grown in the presence of MIC50 of EMB, SPX and combination resulted in significant surface changes as was evident from decreased limiting fluorescence (Fmax) intensity of 1-anilinonaphthalene-8-sulfonate (ANS). Thus, the results of this study suggested that ethambutol and sparfloxacin in combination exerted their antimycobacterial effect principally due to their action on phosphatidylinositolmannosides (PIMs) and mycolic acids, which form the permeability barrier of mycobacteria.

Anti-Infective Agents↗
PubMedDate not supplied

[The comparative action of isoniazid, rifampicin and ethambutol on liver function].

It has been established in experiments on white rats that antituberculous drugs (isoniazid, rifampicin, ethambutol) given in toxic doses affect the liver, its membranes and organelles, inhibit bile production and bioenergy. This is supported by activation of aspartate and alanine aminotransferases, (ALT and AST), alkaline phosphatase in blood serum and acid phosphatase in the liver, by a decrease of the activity of Na(+)-, K(+)-ATPase, succinate dehydrogenase and cytochromoxidase in the liver, lowering of the rate of bile secretion, excretion of bile acids, bilirubin and cholesterol with bile. Provided the drugs are administered in combination, the hepatotoxicity rises, particularly in combination of isoniazid with rifampicin, and especially as isoniazid is combined with rifampicin and ethambutol.

Animals↗
PubMed2004

Standardization of the method for estimation of ethambutol in pharmaceutical preparations and biological fluid.

A simple column chromatographic method for determination of ethambutol (EMB) in pharmaceutical preparations containing EMB in combination with other anti-TB drugs is presented. The method involved extraction of EMB into an organic solvent, followed by basification and column chromatographic separation on Amberlite CG 50 (100-200 mesh) and elution with suitable eluants and estimation at a wavelength of 270 nm. The assay was linear from 25 to 400 microg/ml. The relative standard deviations of intra and inter day assays were lower than 5%. Ethambutol was recovered from human urine quantitatively and stable for a period of at least one week in urine stored at -20 degrees C.

Antitubercular Agents↗
PubMed2005

Development of a pyrosequencing approach for rapid screening of rifampin, isoniazid and ethambutol-resistant Mycobacterium tuberculosis.

SETTING: The need to minimize the transmission of drug-resistant Mycobacterium tuberculosis requires rapid identification procedures. OBJECTIVE: To develop a pyrosequencing approach for rapid screening of rifampin, isoniazid and ethambutol-resistant M. tuberculosis based on characterization of resistance-associated hot mutations. DESIGN: Three pairs of PCR primers and three pyrosequencing sequencing primers for detecting mutations at codon 526 and 531 of the rpoB gene, codon 315 of the katG gene, and codon 306 of the embB gene were chosen. The sensitivity of the pyrosequencing approach was determined by assaying PCR products generated from 10-fold serial dilutions of the DNA from the H37Rv strain. The efficacy of the pyrosequencing approach was evaluated by analyzing clinical isolates with a known antibiotic phenotype. RESULTS: Resistance-associated hot mutations could be determined within 2 h after PCR amplification using pyrosequencing. About 45 fg DNA per reaction was required to obtain sufficient PCR products to produce a clear, accurate pyrosequencing pattern. No mutations were found in all 20 drug-susceptible clinical isolates, while all isolates with mutations showed corresponding drug resistances. CONCLUSION: This pyrosequencing approach can be used for rapid screening of rifampin-, isoniazid- and ethambutol-resistant M. tuberculosis prior to standard drug susceptibility testing.

Antibiotics, Antitubercular↗
PubMed2006

Ethambutol dosage for the treatment of children: literature review and recommendations.

The currently recommended daily dose of ethambutol (EMB) for the treatment of tuberculosis (TB) in children varies from a maximum daily dose of 15 mg/kg body weight daily (without a range) to 15-20 mg/kg and 20 mg/ kg (range 15-25 mg/kg). Published evidence relating to the dosage, toxicity and pharmacokinetics of EMB in children and adults is reviewed and a dose of EMB for use in childhood is recommended. Using key words 'ethambutol', 'childhood', 'TB', 'pharmacokinetics', 'bioavailability' and 'toxicity', Medline searches were conducted; cross-references were sought from original papers, books and conference proceedings dating from 1961. When English summaries were available, data were extracted from papers in languages other than English. EMB has a dose-related efficacy best seen when given to adults alone or with a single other drug. Together with isoniazid (INH), a dose of 15 mg/kg EMB gave better results than 6 mg/kg, and 25 mg/kg better than 15 mg/kg. The occurrence of ocular toxicity was also dose-related; >40% of adults developed toxicity at doses of >50 mg/ kg, and 0-3% at a dose of 15 mg/kg/daily. Peak serum EMB concentrations increase in relation to dose, but are significantly lower in children receiving the same dosage. In only 2 of 3811 children (0.05%) receiving EMB doses of 15-30 mg/kg was EMB stopped due to possible ocular toxicity; children of all ages can be given EMB in daily doses of 20 mg/kg (range 15-25 mg/kg) and three times weekly intermittent doses of 30 mg/kg body weight without undue concern.

Adult↗
PubMed1991

[Comparative hepatic toxicity of isoniazid, rifampicin and ethambutol].

Isoniazid, rifampicin and ethambutol administered in equimolecular dosages (50, 250 and 100 mg/kg, respectively) for 4 days caused liver affection. This was manifested by elevated activity of serum aminotransferases and alkaline phosphatase, inhibition of lipid peroxidation of hepatocyte membranes and antioxidative system dysfunctions. Isoniazid and rifampicin were proved to be most hepatotoxic. The combined use of antituberculous drugs increases their membrane-damaging action, especially when isoniazid and rifampicin are used together, but mostly when isoniazid in combination with rifampicin and ethambutol is applied.

Animals↗
PubMed1991

[Toxic damage of the optic nerve in treatment with ethambutol in a patient on chronic dialysis].

The authors give an account of a 57-year-old male patient who was regularly dialyzed for two years and treated because of suspect TB of the spine with antituberculotics, incl. ethambutol. In the course of 8-9 months he was given 17.9 mg/kg ethambutol per day. Because of the practically zero excretion by the damaged kidney the drug cumulated in the serum and reached toxic levels before dialysis. Gradual deterioration of eyesight developed (central acuity and colour sense) which resulted in bilateral atrophy of the optic nerves with concentric narrowing of the visual field.

Ethambutol↗