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

Arthritis Drug Raises Risk of Tuberculosis
Source: MedicineNet Ankylosing Spondylitis Specialty [2009.07.10]
Title: Arthritis Drug Raises Risk of Tuberculosis
Category: Health News
Created: 7/10/2009 7:00:00 AM
Last Editorial Review: 7/10/2009

Tuberculosis
Source: MedicineNet Erythema Nodosum Specialty [2008.01.17]
Title: Tuberculosis
Category: Diseases and Conditions
Created: 12/31/1997
Last Editorial Review: 1/17/2008

Extensively Drug-Resistant Tuberculosis (XDR TB)
Source: MedicineNet ICU Psychosis Specialty [2007.05.30]
Title: Extensively Drug-Resistant Tuberculosis (XDR TB)
Category: Diseases and Conditions
Created: 5/30/2007
Last Editorial Review: 5/30/2007

Opinions: Fighting TB; Currency Transaction Tax
Source: Health News from Medical News Today [2009.11.19]
Innovation, Coordination Needed To 'Bring TB Research Into The 21st Century' Though tuberculosis "is one of the world's leading killers … few citizens, scientists and policymakers are demanding more attention to TB research, treatment and prevention.

Global Fund Approves $2.4B For Ninth Round Grants
Source: HIV / AIDS News From Medical News Today [2009.11.16]
During its recent board meeting in Addis Ababa, Ethiopia, the Global Fund to Fight AIDS, Tuberculosis and Malaria approved $2.4 billion for the three diseases, PlusNews reports. The money is for the fund's "ninth round of grants, bringing the total amount of approved funding since its inception in 2001 to $18.4 billion," according to the publication.

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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

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.

A Randomized, Double-Blind, Comparative Study of Azithromycin Versus Clarithromycin in Combination With Ethambutol for the Treatment of Disseminated Mycobacterium Avium Complex (MAC) Infection in AIDs Patients [Completed]
To evaluate the efficacy and safety of two different doses of azithromycin in combination with ethambutol for the treatment of patients with Mycobacterium avium complex (MAC) infection, and to determine whether an azithromycin-containing regimen is at least as safe and effective as the same regimen containing clarithromycin..

A Three-Arm Comparative Trial for the Treatment of MAC Bacteremia in AIDS: A Clarithromycin/Ethambutol Regimen Containing Rifabutin (450 Mg) or Rifabutin (300 Mg) or Placebo [Completed]
To compare the efficacy of clarithromycin/ethambutol with placebo or with rifabutin at two different doses in reducing colony-forming units (CFUs) by 2 or more logarithms in patients with Mycobacterium avium Complex bacteremia and maintaining this response until 16 weeks post-randomization. To assess survival and comparative tolerability among the three treatment regimens.

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