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MYAMBUTOL should not be used alone, in initial treatment or in retreatment. MYAMBUTOL should be administered on a once every 24-hour basis only. Absorption is not significantly altered by administration with food. Therapy, in general, should be continued until bacteriological conversion has become permanent and maximal clinical improvement has occured.
MYAMBUTOL is not recommended for use in pediatric patients under thirteen years of age since safe conditions for use have not been established.
Initial Treatment: In patients who have not received previous antituberculous therapy, administer MYAMBUTOL 15 mg/kg (7 mg/lb) of body weight, as a single oral dose once every 24 hours. In the more recent studies, isoniazid has been administered concurrently in a single, daily, oral dose.
Retreatment: In patients who have received previous antituberculous therapy, administer MYAMBUTOL 25 mg/kg (11mg/lb) of body weight, as a single oral dose once every 24 hours. Concurrently administer at least one other antituberculous drug to which the organisms have been demonstrated to be susceptible by appropriate in vitro tests. Suitable drugs usually consist of those not previously used in the treatment of the patient. After 60 days of MYAMBUTOL administration, decrease the dose to 15 mg/kg (7 mg/lb) of body weight, and administer as a single oral dose once every 24 hours.
During the period when patient is on a daily dose of 25 mg/kg, monthly eye examinations are advised.
See Table for easy selection of proper weight-dose tablet(s).
Off-Label Use and Dosage (Adult)
Guideline-Supported Use
Condition1
Developed by:
Class of Recommendation:
Strength of Evidence:
Dosing Information
Dosage
Disseminated infection due to Mycobacterium avium-intracellulare group - HIV infection
Disseminated infection due to Mycobacterium avium-intracellulare group; Prophylaxis - HIV infection
Dosing Information
Dosage
Condition2
There is limited information regarding Off-Label Non–Guideline-Supported Use of Ethambutol in adult patients.
Pediatric Indications and Dosage
FDA-Labeled Indications and Dosage (Pediatric)
Pulmonary tuberculosis; Adjunct(13 years or older)
Dosing Information
Dosage
Condition2
There is limited information regarding FDA-Labeled Use of Ethambutol in pediatric patients.
Off-Label Use and Dosage (Pediatric)
Guideline-Supported Use
Condition1
Developed by:
Class of Recommendation:
Strength of Evidence:
Dosing Information
Dosage
Condition2
There is limited information regarding Off-Label Guideline-Supported Use of Ethambutol in pediatric patients.
Non–Guideline-Supported Use
Condition1
Dosing Information
Dosage
Condition2
There is limited information regarding Off-Label Non–Guideline-Supported Use of Ethambutol in pediatric patients.
Contraindications
MYAMBUTOL is contraindicated in patients who are known to be hypersensitive to this drug. It is also contraindicated in patients with known optic neuritis unless clinical judgement determines that it may be used. MYAMBUTOL is contraindicated in patients who are unable to appreciate and report visual side effects or changes in vision (e.g., young children, unconscious patients).
Warnings
MYAMBUTOL may produce decreases in visual acuity which appear to be due to optic neuritis. This effect may be related to dose and duration of treatment. This effect is generally reversible when administration of the drug is discontinued promptly. However, irreversible blindness has been reported. (See PRECAUTIONS and ADVERSE REACTIONS).
liver toxicities including fatalities have been reported (see ADVERSE REACTIONS). Baseline and periodic assessment of hepatic function should be performed.
Precautions
MYAMBUTOL ethambutol hydrochloride is not recommended for use in pediatric patients under thirteen years of age since safe conditions for use have not been established.
Patients with decreased renal function need the dosage reduced as determined by serum levels of MYAMBUTOL, since the main path of excretion of this drug is by the kidneys.
Because this drug may have adverse effects on vision, physical examination should include ophthalmoscopy, finger perimetry and testing of color discrimination. In patients with visual defects such as cataracts, recurrent inflammatory conditions of the eye, optic neuritis, and diabetic retinopathy, the evaluation of changes in visual acuity is more difficult, and care should be taken to be sure the variations in vision are not due to the underlying disease conditions. In such patients, consideration should be given to relationship between benefits expected and possible visual deterioration since evaluation of visual changes is difficult. (For recommended procedures, see next paragraphs under ADVERSE REACTIONS.)
As with any potent drug, baseline and periodic assessment of organ system functions, including renal, hepatic, and hematopoietic, should be performed.
Adverse Reactions
Clinical Trials Experience
MYAMBUTOL may produce decreases in visual acuity, including irreversable blindness, which appear o be due to optic neuritis. Optic neuropathy including optic neuritis or retrobulbar neuritis occuring in association with ethambutol therapy may be characterized by one or more of the following events: decreased visual acuity, scotoma, color blindness, and/or visual defect. These events have also been reported in the absence of a diagnosis of optic or retrobulbar neuritis.
Patients should be advised to report promptly to their physician any change of visual acuity
The change in visual acuity may be unilateral or bilateral and hence each eye must be tested separately and both eyes tested together. Testing of visual acuity should be performed before beginning MYAMBUTOL therapy and periodically during drug administration, except that it should be done monthly when a patient is on a dosage of more than 15 mg per kilogram per day. Snellen eye charts are recommeneded for testing of visual acuity. Studies have shown that there are definite fluctuations of one or two lines of the Snellen chart in the visual acuity of many tuberculous patients not receiving MYAMBUTOL.
The following table may be useful in interpreting possible changes in visual acuity attributable to MYAMBUTOL.
In general, changes in visual acuity less than those indicated under "Significant Number of Lines" and "Decrease Number of Points" may be due to chance variation, limitations of the testing method, or physiologic variability. Conversely, changes in visual acuity equaling or exceeding those under "Significant Number of LInes" and "Decrease Number of Points" indicate need for retesting and careful evaluation of the patient's visual status. If careful evaluation confirms the magnitude of visual change and fails to reveal another cause, MYAMBUTOL should be discontinued and the patient reevaluated at frequent intervals. Progressive decreases in visual acuity during therapy must be considered to be due to MYAMBUTOL.
If corrective glasses are used prior to treatment, these must be worn during visual acuity testing. During 1 to 2 years of therapy, a refractive error may develop which must be corrected in order to obtain accurate test results. Testing the visual acuity through a pinhole eliminates refractive error. Patients developing visual abnormality during MYAMBUTOL treatment may show subjective visual symptoms before, or simultaneously with, the demonstration of decreases in visual acuity, and all patients receiving MYAMBUTOL should be questioned periodically about blurred vision and other subjective eye symptoms.
Recovery of visual acuity generally occurs over a period of weeks to months after the drug has been discontinued. Some patients have received MYAMBUTOL ethambutol hydrochloride again after such recovery without recurrence of loss of visual acuity.
Other adverse reactions reported include: hypersensitivity, anaphylactic/anaphylactoid reaction, dermatitis, erythmea multiforme, pruritus, and joint pain; anorexia, nausea, vomiting, gastrointestinal upset, and abdominal pain; fever, malaise, headache, and dizziness; mental confusion, disorientation, and possible hallucinations; thrombocytopenia, leukopenia and neutropenia. Numbness and tingling of the extremities due to peripheral neuritis have been reported.
Elevated serum uric acid levels occur and precipiation of acute gout has been reported. Pulmonary infiltrates, with or without eosinophilia, also have been reported during MYAMBUTOL therapy. Liver toxicities, including fatalities, have been reported. (See WARNINGS). Since MYAMBUTOL is recommended for therapy in conjunction with one or more other antituberculous drugs, these changes may be related to the concurent therapy. Hypersensitivity syndrome consisting of cutaneous reaction (such as rash or exofoliative dermatitis), eosinophilia, and one or more of the following: hepatitis, pneumonitis, nephritis, myocarditis, pericarditis. Fever and lymphadenopathy may be present.
Postmarketing Experience
There is limited information regarding Postmarketing Experience of Ethambutol in the drug label.
Body as a Whole
Cardiovascular
Digestive
Endocrine
Hematologic and Lymphatic
Metabolic and Nutritional
Musculoskeletal
Neurologic
Respiratory
Skin and Hypersensitivy Reactions
Special Senses
Urogenital
Miscellaneous
Drug Interactions
The results of a study of coadministration of ethambutol (50 mg/kg) with an aluminum hydroxide containing antacid to 13 patients with tuberculosis showed a reduction of mean serum concentrations and urinary excretion of ethambutol of approximately 20% and 13%, respectively, suggesting that the oral absorption of ethambutol may be reduced by these antacid products. It is recommended to avoid concurrent administration of ethambutol with aluminum hydroxide containing antacids for at least 4 hours following ethambutol administration.
There are no adequate and well-controlled studies in pregnant women. There are reports of ophthalmic abnormalities occuring in infants born to women on antituberculous therapy that included ethambutol hydrochloride. MYAMBUTOL should be used during pregnancy only if the benefit justifies the potential risk to the fetus.
MYAMBUTOL has been shown to be teratogenic in pregnant mice and rabbits when given in high doses. When pregnant mice or rabbits were treated with high doses of ethambutol hydrochloride, fettal mortality was slightly but not significantly (P>0.05) increased. Femal rats treated with ethambutol hydrochloride displayed slight but insignificant (P>0.05) decreases in fertility and litter size.
In fetuses born of mice treated with high doses of MYAMBUTOL during pregnancy, a low incidence of cleft palate, exencephaly and abnormality of the vertebral column were observed. Minor abnormalities of the cervical vertebra were seen in the newborn of rats treated with high doses of ethambutol hydrochloride during pregnancy. Rabbits receiving high doses of MYAMBUTOL during pregnancy gave birth to two fetuses with monophthalmmia, one with a shortened right forearm accompanied by bulateral wrist-joint contracture and one with hare lip and cleft palate.
Pregnancy Category (AUS):
Australian Drug Evaluation Committee (ADEC) Pregnancy Category
There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Ethambutol in women who are pregnant.
Labor and Delivery
There is no FDA guidance on use of Ethambutol during labor and delivery.
Nursing Mothers
MYAMBUTOL is excreted into breast milk. The use of MYAMBUTOL should be considered only if the expected benefit to the mother outweighs the potential risk to the infant.
Pediatric Use
MYAMBUTOL ethambutol hydrochloride is not recommended for use in pediatric patients under thirteen years of age since safe conditions have not been established.
Geriatic Use
There are limited date on the use of ethambutol in the elderly. One study of 101 patients, 65 years and older, on multiple drug antituberculosis regimens included 94 patients on ethambutol. No differences in safety of tolerability were observed in these patients compared with that reported in adults in general.
Other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.
Gender
There is no FDA guidance on the use of Ethambutol with respect to specific gender populations.
Race
There is no FDA guidance on the use of Ethambutol with respect to specific racial populations.
Renal Impairment
There is no FDA guidance on the use of Ethambutol in patients with renal impairment.
Hepatic Impairment
There is no FDA guidance on the use of Ethambutol in patients with hepatic impairment.
Females of Reproductive Potential and Males
There is no FDA guidance on the use of Ethambutol in women of reproductive potentials and males.
Immunocompromised Patients
There is no FDA guidance one the use of Ethambutol in patients who are immunocompromised.
Administration and Monitoring
Administration
MYAMBUTOL should not be used alone, in initial treatment or in retreatment. MYAMBUTOL should be administered on a once every 24-hour basis only. Absorption is not significantly altered by administration with food. Therapy, in general, should be continued until bacteriological conversion has become permanent and maximal clinical improvement has occured.
MYAMBUTOL is not recommended for use in pediatric patients under thirteen years of age since safe conditions for use have not been established.
Initial Treatment: In patients who have not received previous antituberculous therapy, administer MYAMBUTOL 15 mg/kg (7 mg/lb) of body weight, as a single oral dose once every 24 hours. In the more recent studies, isoniazid has been administered concurrently in a single, daily, oral dose.
Retreatment: In patients who have received previous antituberculous therapy, administer MYAMBUTOL 25 mg/kg (11mg/lb) of body weight, as a single oral dose once every 24 hours. Concurrently administer at least one other antituberculous drug to which the organisms have been demonstrated to be susceptible by appropriate in vitro tests. Suitable drugs usually consist of those not previously used in the treatment of the patient. After 60 days of MYAMBUTOL administration, decrease the dose to 15 mg/kg (7 mg/lb) of body weight, and administer as a single oral dose once every 24 hours.
During the period when patient is on a daily dose of 25 mg/kg, monthly eye examinations are advised.
See Table for easy selection of proper weight-dose tablet(s).
Monitoring
There is limited information regarding Monitoring of Ethambutol in the drug label.
Description
IV Compatibility
There is limited information regarding IV Compatibility of Ethambutol in the drug label.
Overdosage
Acute Overdose
Signs and Symptoms
Description
Management
Description
Chronic Overdose
There is limited information regarding Chronic Overdose of Ethambutol in the drug label.
Pharmacology
There is limited information regarding Ethambutol Pharmacology in the drug label.
There is limited information regarding Pharmacodynamics of Ethambutol in the drug label.
Pharmacokinetics
There is limited information regarding Pharmacokinetics of Ethambutol in the drug label.
Nonclinical Toxicology
There is limited information regarding Nonclinical Toxicology of Ethambutol in the drug label.
Clinical Studies
There is limited information regarding Clinical Studies of Ethambutol in the drug label.
How Supplied
MYAMBUTOL® Ethambutol Hydrochloride Tablets USP
100 mg - round, convex, white, film coated tablets engraved M6 on one side are supplied as follows:
NDC 68850-010-01 - Bottle of 100
400 mg - round, convex, white, scored, film coated tablets engraved with M to the left and 7 to the right of the score on one side are supplied as follows:
NDC 68850-012-01 - Bottle of 100
NDC 68850-012-02 - 10 Blister-packs x 10 Tablets
Storage
Store at controlled room temperature 20° to 25°C (68° to 77°F).
Images
Drug Images
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