Ethambutol (Ethambutol Hydrochloride) - Summary

ETHAMBUTOL SUMMARY

ETHAMBUTOL HYDROCHLORIDE TABLETS, USP

Ethambutol hydrochloride is an oral chemothera-peutic agent which is specifically effective against actively growing microorganisms of the genus Mycobacterium, including M. tuberculosis. It is a white, crystalline powder. Freely soluble in water; soluble in alcohol and in methanol; slightly soluble in ether and in chloroform. It has the chemical formula of: (+)-2,2’(Ethylenediimino)-di-1-butanol dihydrochloride.

Ethambutol Hydrochloride Tablets are indicated for the treatment of pulmonary tuberculosis. It should not be used as the sole antituberculous drug, but should be used in conjunction with at least one other antituberculous drug. Selection of the companion drug should be based on clinical experience, considerations of comparative safety and appropriate in vitro susceptibility studies.

In patients who have not received previous antituberculous therapy, i.e., initial treatment, the most frequently used regimens have been the following:

Ethambutol plus isoniazid

Ethambutol plus isoniazid plus streptomycin.

In patients who have received previous antituberculous therapy, mycobacterial resistance to other drugs used in initial therapy is frequent.

Consequently, in such retreatment patients, ethambutol should be combined with at least one of the second line drugs not previously administered to the patient and to which bacterial susceptibility has been indicated by appropriate in vitro studies. Antituberculous drugs used with ethambutol have included cycloserine, ethionamide, pyrazinamide, viomycin, and other drugs. Isoniazid, aminosalicylic acid, and streptomycin have also been used in multiple drug regimens. Alternating drug regimens have also been utilized.

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NEWS HIGHLIGHTS

Media Articles Related to Ethambutol

'Alarming' Rise Seen in Drug-Resistant Tuberculosis
Source: MedicineNet Tuberculosis Specialty [2012.08.31]
Title: 'Alarming' Rise Seen in Drug-Resistant Tuberculosis
Category: Health News
Created: 8/30/2012 2:05:00 PM
Last Editorial Review: 8/31/2012 12:00:00 AM

Tuberculosis
Source: MedicineNet Neutropenia Specialty [2011.07.22]
Title: Tuberculosis
Category: Diseases and Conditions
Created: 12/31/1997 12:00:00 AM
Last Editorial Review: 7/22/2011 12:00:00 AM

New Mechanism Of TB Drug Resistance Identified
Source: Health News from Medical News Today [2013.06.15]
Pyrazinamide (PZA) - a frontline tuberculosis (TB) drug - kills dormant persister bacteria and plays a critical role in shortening TB therapy. PZA is used for treating both drug susceptible and multi-drug resistant TB (MDR-TB) but resistance to PZA occurs frequently and can compromise treatment. A recent study, led by researchers at the Johns Hopkins Bloomberg School of Public Health and Huashan Hospital, Fudan University, has identified a new mechanism for PZA-resistance, which provides new insight into the how this mysterious drug works...

Drug-Resistant TB Destroyed By Vitamin C
Source: MRSA / Drug Resistance News From Medical News Today [2013.05.24]
In a striking, unexpected discovery, researchers at Albert Einstein College of Medicine of Yeshiva University have determined that vitamin C kills drug-resistant tuberculosis (TB) bacteria in laboratory culture. The finding suggests that vitamin C added to existing TB drugs could shorten TB therapy, and it highlights a new area for drug design...

Consensus Statement On Research Definitions For Drug-Resistant TB In Children
Source: MRSA / Drug Resistance News From Medical News Today [2013.05.23]
The Journal of the Pediatric Infectious Diseases Society (JPIDS) has released its June issue, which includes a consensus statement of the global Sentinel Project on Pediatric Drug-Resistant Tuberculosis. It establishes standardized definitions, measurements, and other key attributes that will affect research...

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Published Studies Related to Ethambutol

Moxifloxacin versus ethambutol in the initial treatment of tuberculosis: a double-blind, randomised, controlled phase II trial. [2009.04.04]
BACKGROUND: New treatments are needed to shorten the time required to cure tuberculosis and to treat drug-resistant strains. The fluoroquinolone moxifloxacin is a promising new agent that might have additive activity to existing antituberculosis agents. We assessed the activity and safety of moxifloxacin in the initial stage of tuberculosis treatment... INTERPRETATION: Moxifloxacin improved culture conversion in the initial phase of tuberculosis treatment. Trials to assess whether moxifloxacin can be used to shorten the duration of tuberculosis treatment are justified.

Clarithromycin vs ciprofloxacin as adjuncts to rifampicin and ethambutol in treating opportunist mycobacterial lung diseases and an assessment of Mycobacterium vaccae immunotherapy. [2008.07]
BACKGROUND: The mainstays of treatment for pulmonary disease caused by opportunist mycobacteria are rifampicin (R) and ethambutol (E). The role of macrolides, quinolones and immunotherapy with Mycobacterium vaccae is not clear. A trial was undertaken to compare clarithromycin (Clari) and ciprofloxacin (Cipro) as third drugs added after 2 years of treatment with R and E for pulmonary disease caused by M avium-intracellulare (MAC), M malmoense and M xenopi (REClari and RECipro). An optional comparison of immunotherapy with M vaccae vs no immunotherapy was also performed... CONCLUSION: Considering all three species together, there were no differences in outcome between the REClari and RECipro groups. Immunotherapy did not improve outcome. New therapies, optimised management of co-morbid conditions and a more holistic approach must be explored in the hope of improving outcome.

Moxifloxacin versus ethambutol in the first 2 months of treatment for pulmonary tuberculosis. [2006.08.01]
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... 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.

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Clinical Trials Related to Ethambutol

Effect of Weight and/or Obesity on Ethambutol Drug Concentrations [Recruiting]
This study is designed to measure drug concentrations in the blood of healthy volunteers administered a single dose of ethambutol. Our hypothesis is that volunteers with a body mass index (BMI) 25-40 kg/m2 will remove ethambutol more quickly from the blood than leaner volunteers, and those with a BMI > 40 kg/m2 will have even greater clearance than those who are leaner.

Controlled Comparison of Two Moxifloxacin Containing Treatment Shortening Regimens in Pulmonary Tuberculosis [Recruiting]
REMoxTB is a study for the "Rapid Evaluation of Moxifloxacin in the treatment of sputum smear positive tuberculosis". REMoxTB aims to find and evaluate new drugs and regimens that shorten the duration of tuberculosis therapy.

The purpose of REMoxTB is to evaluate the efficacy, safety and acceptability of two moxifloxacin-containing treatment combinations to determine whether substituting ethambutol with moxifloxacin in one combination, and/or substituting isoniazid with moxifloxacin in another combination, makes it possible to reduce the duration of treatment for TB.

A Study of Rifabutin, Used Alone or With Ethambutol in the Prevention of Mycobacterium Avium Complex (MAC) Bacteremia in Patients With AIDS [Completed]
To optimize Mycobacterium avium Complex (MAC) prophylaxis in AIDS patients by measuring serum rifabutin levels and adjusting the dose accordingly. To combine rifabutin with ethambutol to examine the effect of combination therapy in preventing or delaying the incidence of MAC bacteremia in this patient population.

A Phase II/III Trial of Rifampin, Ciprofloxacin, Clofazimine, Ethambutol, and Amikacin in the Treatment of Disseminated Mycobacterium Avium Infection in HIV-Infected Individuals. [Completed]
To compare the effectiveness and toxicity of two combination drug treatment programs for the treatment of disseminated Mycobacterium avium infection in HIV seropositive patients. [Per 03/06/92 amendment: to evaluate the efficacy of azithromycin when given in conjunction with either ethambutol or clofazimine as maintenance therapy.] Disseminated M. avium infection is the most common systemic bacterial infection complicating AIDS in the United States. The prognosis of patients with disseminated M. avium is extremely poor, particularly when it follows other opportunistic infections or is associated with anemia. Test tube studies and clinical data indicate that the best treatment program may include clofazimine, ethambutol, a rifamycin derivative, and ciprofloxacin. Test tube and animal studies indicate that amikacin is a bactericidal (bacteria destroying) drug that works better when used with ciprofloxacin. Its role in treatment programs is a key issue because of toxicity and because it must be administered parenterally (by injection or intravenously).

The Safety and Effectiveness of Clarithromycin Plus Ethambutol Used With or Without Clofazimine in the Treatment of MAC in Patients With AIDS [Completed]
PRIMARY: To assess the tolerability of the combination regimen of clarithromycin plus ethambutol with or without clofazimine in patients with disseminated Mycobacterium avium Complex (dMAC).

SECONDARY: To determine the proportion of patients achieving a sterile blood culture along with the time required to achieve it. To determine the duration of bacteriological response, defined as length of time that blood cultures remain sterile.

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