Ethambutol side effects

The major toxicity associated with ethambutol use is retrobulbar neuritis impairing visual acuity and red-green color discrimination this side effect is dose related and reverses slowly once the drug is discontinued. Mild GI intolerance, allergic reaction, fever, dizziness, and mental confusion are also possible. Hyperuricemia is associated with ethambutol use due to a decreased renal excretion of urates gouty arthritis may result. 

A. Ethambutol is associated with retrobulbar neuritis, resulting in loss of central vision and impaired red-green discrimination. Ethionamide (B) is an analogue of isonicotinic acid and is associated with GI intolerance and peripheral neuropathy, but not the optic neuritis or color vision discrimination problems. Aminosalicylic acid (C) can cause GI irritation and bleeding problems, so caution is required in peptic ulcer patients. It has no neurological side effects. Rifampin (D) is associated with red-orange discoloration of saliva, tears, and urine but not the color vision problems. Isoniazid (E) is associated with peripheral neuritis in chronic alcoholics and malnourished individuals and requires pyridoxine supplements. It is not associated with optic neuritis. 

Ethambutol suppresses the growth of isoniazid- and streptomycin-resistant tubercle bacilli. The most important but not common side effects are optic neuritis, decreased visual acuity, and inability to perceive the color green. 

ETHAMBUTOL ANTIVIRALS-DIDANOSINE Possibly t adverse effects (e.g. peripheral neuropathy) with didanosine Additive side-effects Monitor closely for development of peripheral neuropathy but no dose adjustment is required... 

Side effects caused by isoniazid, rifampin, pyrazinamide, and ethambutol are common and can include hepatotoxic-ity, peripheral neuropathy, optic neuritis, and Gl side effects. All four agents can potentially be hepatotoxic, but this side effect is most frequently associated with isoniazid and rifampin. Peripheral neuropathy is most commonly associated with isoniazid, whereas optic neuritis is associated with ethambutol. The metabolism of isoniazid is genetically predetermined. Patients of Scandinavian, European, and African descent metabolize isoniazid slower (slow acetylators) and are therefore more predisposed to hepatotoxicity and peripheral neuropathy due to isoniazid. Fast acetylators include people of Asian or American Indian descent and are less predisposed to these adverse effects. 

The use of ethambutol in the chemotherapy of tuberculosis is described in the following text. The most important side effect is optic neuritis, resulting in decreased visual acuity and loss of ability to differentiate red from green. The incidence of this reaction is proportional to the dose of ethambutol and is observed in 15% of patients receiving 50 mg/kg day, in 5% of patients receiving 25 mg/kg per day, and fewer than 1% of patients receiving daily doses of 15 mg/kg (the recommended dose for treatment of tuberculosis). The intensity of the visual difficulty is related to the duration of therapy after the decreased visual acuity first becomes apparent, and may be unilateral or bilateral. Tests of visual acuity and red-green discrimination prior to the start of therapy and periodically thereafter are thus... 

Ethambutol produces very few untoward reactions. Fewer than 2% of nearly 2000 patients who received daily doses of 15 mg/kg of ethambutol had adverse reactions 0.8% experienced diminished visual acuity, 0.5% had a rash, and 0.3% developed drug fever. Other side effects that have been observed are pruritus, joint pain, gastrointestinal upset, abdominal pain, malaise, headache, dizziness, mental confusion, disorientation, and possible hallucinations. Numbness and tingling of the fingers owing to peripheral neuritis are infrequent. Anaphylaxis and leukopeifia are rare. 

Allergic side effects after treatment with ethambutol are extremely rare. 

Ethambutol causes many side effeets that can limit its utilization in disease treatment. The most common side effects observed are dizziness, blurred vision, color blindness, nausea, vomiting, stomach pain, loss of appetite, headache, rash, itching, breathlessness, swelling of the face, hps or eyes, numbness or tingling in the fingers or toes (Jnawali and Ryoo, 2013 Chatteijee et al., 1986). Due to the effect of ethambutol on the vision, patients should check on their vision at least once a month (Jnawali and Ryoo, 2013). 

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