HWN Suggests

Ethambutol: friend or foe?

Ethambutol (EMB) is one of the first-line antimycobacterial drugs used to treat tuberculosis and is also used to treat atypical mycobacterium infections. It is almost always used in combination with other antimycobacterial drugs. Ever since the drug’s introduction in the 1960s, there have been descriptions of optic neuropathy associated with EMB. Despite a clear association of EMB-induced optic neuropathy, many questions remain unanswered, namely, which tests are more accurate to monitor toxicity, how often should they be performed and once the optic neuropathy is present, how much of it is reversible?

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Articles of Interest

Ethambutol efficacy and toxicity

EMB has been used to treat tuberculosis almost in children as long as it has been used in adults. Its use has generally, but not always, been confined to children over 3 years of age, because of concern about the risk of ocular toxicity and the difficulty of assessing ocular function in young children.

Ethambutol for treatment of tuberculosis

This leaflet is for parents and carers about how to use this medicine in children. Our information may differ from that provided by the manufacturers, because their information usually relates to adults.

Ethambutol in tuberculosis: time to reconsider?

There is a concern that toxicity may develop in children too young to report early visual symptoms. Understandably, reviews of anti-TB chemotherapy in children, consensus statements, and World Health Organisation (WHO) directives advise against the use of ethambutol in young children.

Ethambutol Optic Neuropathy

Ethambutol (EMB) is an antibiotic used to treat infection by Mycobacterium species, particularly Mycobacterium tuberculosis and non- tubercular infections like M. avium complex and M. kansasii. Unfortunately, one serious and vision threatening side effect of EMB is ethambutol-induced optic neuropathy (EON). Less common side effects of EMB include peripheral neuropathy, cutaneous reactions, thrombocytopenia, and hepatitis.

Resources

Ethambutol

Ethambutol is a drug used, alone or in combination with other drugs, to treat tuberculosis and other infections. It is sold under the trade names Myambutol (X-GEN Pharmaceuticals) and Servambutol (Sandoz). Although it is effective, it has several adverse side effects, such as vision, liver, and allergy problems.

TB Drug Dosage Calculator

Calculates drug dosing for Pyrazinamide and Ethambutol using Lean Body Weight(James Equation).

StatPearls

Ethambutol(EMB) has been available to treat tuberculosis (TB) since the 1960s. The original formulation of EMB was a racemic mixture of its L and D forms. The D form of ethambutol was known for its therapeutic effect; however, the L form was known for its toxicity and hence, discontinued. Ethambutol is used for the treatment of pulmonary tuberculosis. It should not be used alone but rather in tandem with at least one other antituberculosis drug such as isoniazid.

TB Alliance

The most common side effect of ethambutol is optic neuropathy, generally reversible although irreversible blindness has been reported. Hepatotoxicity has been also been reported. Other side effects that have been observed are pruritus, joint pain, gastrointestinal upset, abdominal pain, malaise, headache, dizziness, mental confusion, disorientation, and possible hallucinations, as per the FDA label.