Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ETHAMBUTOL”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed1986

Evaluation of streptomycin and ethambutol concentrations for susceptibility testing of Mycobacterium tuberculosis by radiometric and conventional procedures.

Clinical isolates of Mycobacterium tuberculosis were used to compare various concentrations of streptomycin and ethambutol in the BACTEC 460 (Johnston Laboratories, Inc., Towson, Md.) radiometric method for drug susceptibility testing with those in the conventional method. Streptomycin used at 2.0 micrograms/ml for both methods showed a 0.99 agreement with susceptible strains and a 0.97 agreement with resistant strains. Ethambutol used at 2.5 micrograms/ml for the radiometric method showed 1.00 agreement with both susceptible and resistant strains when compared with ethambutol at 5.0 micrograms/ml for the conventional method.

Drug Resistance, Microbial↗
PubMed1997

Reliability of mycobacteria growth indicator tube for testing susceptibility of Mycobacterium tuberculosis to ethambutol and streptomycin.

The reliability of mycobacterial growth indicator tubes (MGIT) for testing susceptibility of Mycobacterium tuberculosis to ethambutol and streptomycin was evaluated by comparing MGIT results to those obtained by the radiometric BACTEC TB system and the method of proportion. The method of proportion was considered the reference method. To resolve discrepancies, all three testing methods were repeated. For the 74 isolates evaluated, initial ethambutol results agreed by all three methods for 64 (86.5%) of them; 58 were susceptible and 6 were resistant. MGIT and method-of-proportion results agreed for 67 isolates, and BACTEC results agreed with method-of-proportion results for 71 (P = 0.096). Initial streptomycin results obtained by all three methods agreed for 69 (93.2%) isolates: 55 were susceptible and 14 were resistant. MGIT and method-of-proportion results were concordant for 69 isolates, and BACTEC and method-of-proportion results agreed for 73 (P = 0.049). The mean times to MGIT results were 5.58 +/- 0.10 days (range, 3 to 9 days) for ethambutol and 5.47 +/- 0.11 days (range, 3 to 9 days) for streptomycin, compared to a mean of 7.41 +/- 0.20 days (range, 4 to 12 days) for both drugs with the BACTEC system (P < 0.001).

Antibiotics, Antitubercular↗
PubMed1999

Evaluation of a bacteriophage-based assay (phage amplified biologically assay) as a rapid screen for resistance to isoniazid, ethambutol, streptomycin, pyrazinamide, and ciprofloxacin among clinical isolates of Mycobacterium tuberculosis.

Rapid molecular assays for the detection of mutations associated with rifampin resistance in Mycobacterium tuberculosis are commercially available. However, they are complex and expensive and have predictive values of 90 to 95%. Molecular assays for other drugs are less predictive of resistance. Ideally, assays based on phenotypic markers should be used for susceptibility testing, but these can take weeks to complete. We previously described a rapid phenotypic assay, the phage amplified biologically (PhaB) assay, for the rapid determination of rifampin and isoniazid susceptibility in clinical isolates of M. tuberculosis. In this study, we extended the assay to the study of ethambutol, pyrazinamide, streptomycin, and ciprofloxacin. After the optimization of antibiotic concentrations and incubation conditions, the assay was applied to each drug for a total of 157 isolates. The correlations between the results of the PhaB assay and the resistance ratio method were 94% for isoniazid, 96% for streptomycin, 100% for ciprofloxacin, 88% for ethambutol, and 87% for pyrazinamide. For ciprofloxacin, ethambutol, and pyrazinamide, significantly better correlations were found when a 90% reduction in plaque count was used as the cutoff. Turnaround times for the PhaB assay were 2 to 3 days, compared with 10 days for the resistance ratio method. We believe that this low-cost assay may have widespread applicability for the rapid screening of drug resistance in M. tuberculosis isolates, especially in developing countries.

Antitubercular Agents↗
PubMed1977

Mycobacterium tuberculosis resistance to rifampicin and ethambutol: a clinical survey.

Ninety-seven cultures of Myco, tuberculosis referred to the Tuberculosis Reference Laboratory, Cardiff during 1972-73 and found to be resistant to rifampicin or ethambutol were studied. Resistance to each drug appeared equally common. Few lower grades of rifampicin resistance occurred, cultures tending to be either fully sensitive or highly resistant. Intermediate grades of ethambutol resistance, however, were common, and a majority of highly resistant cultures were preceded by cultures showing lower grades of resistance. Case-notes were obtained on 84 patients (87%) and revealed no cases of primary resistance. In the three years since first developing resistance 36% of patients died: in the majority tuberculosis was a major cause of death. Half the patients had been prescribed unsatisfactory drug regimens containing rifampicin or ethambutol by their physicians, and only a small minority were considered to have co-operated well. One-third had discharged themselves from hospital against medical advice and only 21% attended clinics regularly. These two factors probably accounted for the development of resistance in most cases.

Drug Resistance, Microbial↗
PubMed1977

Bactericidal activity of streptomycin, isoniazid, rifampin, ethambutol, and pyrazinamide alone and in combination against Mycobacterium Tuberculosis.

Log-phase cultures of Mycobacterium tuberculosis in Tween-albumin medium were exposed to streptomycin, isoniazid, rifampin, ethambutol, and pyrazinamide in concentrations in the range likely to be present in serum during treatment of patients. The bactericidal activity of the drugs was measured as the decrease in viable counts at 4 and 7 days. The activity of single drugs was highest for streptomycin and next highest for rifampin and isoniazid, but ethambutol only started to kill after 4 days. When exposed to 2 drugs, bactericidal synergism was found with streptomycin/isoniazid and isoniazid/ethambutol; additivity, with streptomycin/rifampin; indifference, with isoniazid rifampin and streptomycin/ethambutol; and antagonism, with rifampin/ethambutol and isoniazid/pyrazinamide. When cultures were exposed to the 3 drugs, isoniazid, rifampin, and ethambutol, marked antagonism was found between isoniazid and rifampin, whereas the addition of isoniazid or an increase in its concentration increased the bactericidal activity.

Drug Interactions↗
PubMed1983

Ethambutol dose-plasma level correlation studies in guinea pigs.

Plasma ethambutol concentration-time curves, determined in guinea pigs after 50, 100, or 200 mg/kg single oral doses, were compared with those reported for other species. The plasma concentration-time curve associated with antituberculosis activity in mouse, monkey, and humans could not be reproduced in guinea pigs. In guinea pigs, the rate of ethambutol elimination from plasma (40-min half-life) was 4 times faster than that reported for the mouse or for humans (161-min half-life). This finding tends to negate extrapolation of ethambutol dose-plasma concentration data from other species to guinea pig studies intended to predict clinical utility.

Animals↗
PubMed2006

Moxifloxacin versus ethambutol in the first 2 months of treatment for pulmonary tuberculosis.

RATIONALE: Moxifloxacin has promising preclinical activity against Mycobacterium tuberculosis, but has not been evaluated in multidrug treatment of tuberculosis in humans. OBJECTIVE: To compare the impact of moxifloxacin versus ethambutol, both in combination with isoniazid, rifampin, and pyrazinamide, on sputum culture conversion at 2 mo as a measure of the potential sterilizing activity of alternate induction regimens. METHODS: Adults with smear-positive pulmonary tuberculosis were randomized in a factorial design to receive moxifloxacin (400 mg) versus ethambutol given 5 d/wk versus 3 d/wk (after 2 wk of daily therapy). All doses were directly observed. MEASUREMENTS: The primary endpoint was sputum culture status at 2 mo of treatment. RESULTS: Of 336 patients enrolled, 277 (82%) were eligible for the efficacy analysis, 186 (67%) were male, 175 (63%) were enrolled at African sites, 206 (74%) had cavitation on chest radiograph, and 60 (22%) had HIV infection. Two-month cultures were negative in 71% of patients (99 of 139) treated with moxifloxacin versus 71% (98 of 138) treated with ethambutol (p = 0.97). Patients receiving moxifloxacin, however, more often had negative cultures after 4 wk of treatment. Patients treated with moxifloxacin more often reported nausea (22 vs. 9%, p = 0.002), but similar proportions completed study treatment (88 vs. 89%). Dosing frequency had little effect on 2-mo culture status or tolerability of therapy. CONCLUSIONS: The addition of moxifloxacin to isoniazid, rifampin, and pyrazinamide did not affect 2-mo sputum culture status but did show increased activity at earlier time points.

Adult↗
PubMed1982

Ethambutol-induced thrombocytopenia.

Extreme thrombocytopenia, purpura, and melena developed in a 71-year-old woman four days after ethambutol administration was started. The macrophage inhibition factor test was positive for ethambutol, and the thrombocytopenia subsided shortly after discontinuation of the drug therapy. The sequence of events in this patient suggests that, although previously unreported, thrombocytopenia should be added to the list of side effects of ethambutol.

Aged↗
PubMed1999

Replacement of streptomycin by ethambutol in the intensive phase of tuberculosis treatment: no effect on compliance.

SETTING: Seven tuberculosis clinics in the National Tuberculosis Programme of Madagascar. OBJECTIVE: To compare the treatment efficacy and tolerance of regimens including either streptomycin or ethambutol for patient compliance during initial treatment of smear-positive tuberculosis. DESIGN: The 1023 patients included in the study were randomly divided into two treatment groups-one to receive streptomycin (S), isoniazid (H), rifampicin (R) and pyrazinamide (Z) (SHRZ), and the other to receive EHRZ, where streptomycin was replaced by ethambutol (E). During the 2-month intensive phase, drug delivery was completely supervised. The same 6-month continuation regimen was then given in both groups. Follow-up consisted of a clinical and bacteriological examination at the end of the second, fifth and eighth months. RESULTS: There was no significant difference between the two regimens as regards compliance with treatment, the number of patients lost or who died, or for bacteriological response during the intensive phase. EHRZ was better tolerated. During the continuation phase, the results of the two groups remained comparable, but treatment failures occurred earlier in the patients who had received streptomycin. CONCLUSION: Patient compliance was not better with streptomycin. The ethambutol-containing regimen was as efficient as the other, and better tolerated. There is no argument for preferring streptomycin in the intensive phase of treatment of smear-positive tuberculosis.

Adolescent↗
PubMed1997

Visual evoked responses in ethambutol induced optic neuritis.

Pattern evoked responses were recorded in 46 patients of tuberculosis on ethambutol and 16 healthy subjects. Deterioration in visual acuity was documented in two patients (4.3%). P100 latency was delayed in 16 cases (34.8%), while in 12 patients (26.1%) both latency and amplitude were affected. A cut off latency value of > or = 140 ms was associated with ophthalmological findings. The incidence of subclinical toxicity as detected by visual evoked response (VER) was higher in older subjects, patients on higher doses of ethambutol (> or = 20 mg/kg/day) and longer duration of treatment. Of two cases with objective ocular signs, one who reported for follow up after two months had recovered completely after stopping ethambutol. Recording of VER is an extremely useful objective test for subclinical optic nerve damage.

Adolescent↗
PubMed2002

Color vision in 42 Congolese patients with tuberculosis receiving ethambutol treatment.

PURPOSE: To study color vision in Congolese patients with tuberculosis receiving ethambutol therapy. METHODS: A prospective, descriptive study of color vision test in patients with systemic tuberculosis receiving ethambutol was performed between April 1995 and January 1998 at the Department of Ophthalmology, University of Kinshasa. Color vision tests were assessed with pseudoisochromatic plates (the Ishihara Pseudo-isochromatic Plates), the AO-HRR (American Optical Handy Rand Rittler), the Bölle and Kastel anomaloscope, Farnsworth-Munsell test (the D-15 and the FM-100). RESULTS: There were 42 patients with a mean age of 33 years (range, 14 to 75 years). The color vision of all the patients was found to be normal as measured by the Ishihara pseudoisochromatic plates. One (2%) patient showed color vision defect (anarchic axis] with the OA-HRR test. Three (7%) of 42 patients displayed blue-yellow color axis or anarchic axis color vision test on the D-15 test. Fifteen (36%) of 42 patients had high total error scores at the Farnsworth-Munsell 100 test. The color axis was as follows: anarchic axis (13.1%), red-green-color and blue-yellow-color combined axis (13.1%), blue-yellow color axis (7.5%). Results of the Bölle and Kastel anomaloscope were normal in all patients. CONCLUSION: Our results confirm the importance of color vision examinations in the detection of the complications of ethambutol treatment.

Adolescent↗
PubMed2002

Treatment of isoniazid-resistant tuberculosis with isoniazid, rifampin, ethambutol, and pyrazinamide for 6 months.

SETTING: In 1992 the Seattle-King County Department of Public Health Tuberculosis Clinic began to treat patients with isoniazid-resistant tuberculosis with a regimen of isoniazid, rifampin, pyrazinamide, and ethambutol daily for 6 months. OBJECTIVE: To conduct a review of clinical and bacteriological outcomes of treatment for patients who received the four-drug, 6-month regimen for isoniazid-resistant tuberculosis. DESIGN: A retrospective review of medical records of TB cases meeting the study criteria, a Mycobacterium tuberculosis isolate resistant to isoniazid, and intent to treat with a 6-month course of isoniazid, rifampin, pyrazinamide, and ethambutol. RESULTS: Through December 1999, 44 consecutive patients with isoniazid-resistant, rifampin-susceptible tuberculosis were started on the four-drug, 6-month daily regimen. Among 42 patients followed until completion of therapy, three required changes in the regimen due to side effects. There was one case of drug-induced hepatotoxicity. Among 39 patients with pulmonary involvement, 37 converted sputum cultures from positive to negative within 2 months of starting treatment. There were no treatment failures. On passive follow-up of at least 2 years on all patients, two patients relapsed. The single patient with bacteriological relapse did not develop further drug resistance. CONCLUSION: The regimen of isoniazid, rifampin, pyrazinamide, and ethambutol given daily for 6 months produced successful outcomes when used in a public health tuberculosis clinic as routine therapy for isoniazid-resistant tuberculosis.

Adolescent↗
PubMed2003

Impact of iron loading on the activity of isoniazid or ethambutol in the treatment of murine tuberculosis.

OBJECTIVE: To assess the impact of iron loading on the activity of isoniazid and ethambutol in the treatment of murine tuberculosis. DESIGN: Iron-loaded and iron-normal female Balb/C mice infected with 1.5 x 10(7) colony forming units of Mycobacterium tuberculosis were treated with either isoniazid or ethambutol for 28 days. RESULTS: For both treatments, the outcome was impaired by the iron loading: bactericidal activity of isoniazid was partially but significantly reduced and ethambutol bactericidal activity was totally inhibited. CONCLUSION: The treatment of tuberculosis in patients with iron loading should be longer than for normal patients or should contain an additional drug.

Animals↗
PubMed2003

[Some aspects of determination of the sensitivity of Mycobacterium tuberculosis to ethambutol using a semiliquid medium].

In addition to the earlier developed rapid technique for determining the drug resistance of Mycobacterium tuberculosis (MBT) to essential antituberculous drugs by using semiliquid medium (SLM), the author proposes a procedure for determining their resistance to ethambutol. She shows it necessary to use the drug only as a powder. The mean minimum suppressing concentrations of ethambutol in the semiliquid medium have been determined for stock cultures, sensitive and resistant strains, which are 3.5 +/- 2.5, 4.5 +/- 1.4, 8.5 +/- 1.6 micrograms/ml. Parallel determination of the sensitivity of 91 MBT strains by using the standard Löwenstein-Jensen medium and SLM has yielded the optimum concentration of ethambutol (5 micrograms/ml), which is marked by the highest (84.4%) percent of coincidence of results.

Antitubercular Agents↗
PubMed2006

[Determination of contents and dissolution of ethambutol hydrochloride in fixed dose combinations for antituberculosis drugs by high performance liquid chromatography with pre-column derivatization].

A reversed-phase high performance liquid chromatographic method (RP-HPLC) with pre-column derivatization and ultraviolet (UV) detection was established to determine ethambutol hydrochloride in fixed dose combinations (FDCs) for anti-tuberculosis drugs. The derivatization was carried out in a non-aqueous environment, where ethambutol hydrochloride was derivatized with phenylethylisocyanate at an optimal molar ratio of 1:6. The extraction recovery was 98.7% with the mean relative standard deviation of 0.70%. The accuracy and precision of the method were all qualified. The linear regression of the standard calibration curve was determined and the linearity was good (r = 0.9993). The method is sensitive, specific, rapid, and can be successfully applied to the quantitation and dissolution of ethambutol hydrochloride in FDCs.

Antitubercular Agents↗
PubMed1991

Visual evoked responses in tuberculous children on ethambutol therapy.

Visual evoked responses (VERs) were recorded in 47 children, aged 3-13 years with tuberculosis, treated with ethambutol (20 mg/kg/day) as a part of the antitubercular regimen. VERs were evoked by monocular whole field stimulation, the stimulus being provided by a black and white checker-board pattern reversed every 560 msec and recorded before the commencement, 2, 4, 6, 9 and 12 months of therapy and between 3 to 6 months after stopping the drug. In the first 6 months of therapy the mean values of latency ranged from 92.8 to 101.3 msec in the 3 to less than 6 years age group and 88.5 to 100.3 msec in children 6-13 years of age. Between 6-12 months of therapy the mean values of latency were between 93.3 to 101.0 msec in the 3 to less than 6 years age group and 96.0 to 101.5 msec in the older group. Between 3-6 months after stopping therapy the means of latency ranged from 92 to 96 msec. The differences were not statistically significant at any point of time. Thus, children do not seem to be at greater risk for developing ethambutol inducted optic damage as compared to adults. Ethambutol in the above stated dose may, therefore, be recommended for inclusion in antitubercular chemotherapy in pediatrics without undue fear of subclinical toxicity.

Child↗
PubMed1987

[Determination of plasma ethambutol with liquid chromatography and ultraviolet spectrophotometry].

The method presented here is based on the ability of ethambutol to give chelates with divalent cationic metals. With copper salts, the chelate presents a characteristic ultraviolet absorbance at 270 nm, making it possible to titrate ethambutol extracted from plasma with chloroform in alkaline medium. The column which was used contained silica (LiChrosorb Si 60, 5 microns) and the mobile phase was a mixture of equal parts of water and acetonitrile, containing copper sulphate and ammonia. The internal standard was a lower homologue of ethambutol with the same chelating ability. The detection limit was 0.15 mg/l. No interference with other antitubercular agents was observed.

Ammonia↗
PubMedDate not supplied

Serum concentration and urinary excretion of ethambutol administered alone and in combination with isoniazid in patients of pulmonary tuberculosis.

Ethambutol (20 mg/kg) was administered orally to 10 patients of pulmonary tuberculosis for seven consecutive days at 8 a.m. after over night fast. On 7th day serum levels were measured at 2, 4, 6, 8 and 24 hr intervals and urinary excretion was estimated at 2, 4, 6 and 24 hr following ethambutol administration. Simultaneous administration of isoniazid (300 mg, orally) for next seven days to the same patients significantly raised the serum levels of ethambutol at 4, 6 and 8 hr and the cumulative per cent dose excreted was decreased significantly at 4, 6 and 24 hr. The serum levels and urinary elimination was not significantly different at 2 hr.

Administration, Oral↗