Ethambutol adverse reaction

Optic neuritis (a decrease in visual acuity and changes in color perception), which appears to be related to the dose given and die duration of treatment, has occurred in some patients receiving ethambutol. Usually, tiiis adverse reaction disappears when the drug is discontinued. Other adverse reactions are dermatitis, pruritus, anaphylactoid reactions (unusual or exaggerated allergic reactions), joint pain, anorexia, nausea, and vomiting. 

Which of the following is a dose-related adverse reaction to ethambutol ... 

Because of the dangerous adverse reactions (including the risk of death), individuals should not take methylphenidate if they have taken a class of drugs known as monamine oxidase (MAO) inhibitors within 14 days. Most MAO inhibitors are antidepressants, but some anti-tuberculosis drugs such as Ethambutol also have MAO effects. Since drug users are prone to many infectious diseases, it is not unheard of for drug abusers to come down with tuberculosis (TB). 

Arguments have been advanced for the abandonment of thiacetazone as an antituberculosis drug (11,12), despite its cheapness, on the grounds that it often causes severe skin reactions, some rapidly fatal, in patients infected with HIV-1 (13). The WHO and lUATLD has recommended careful information and surveillance of possible adverse reactions, particularly cutaneous, in patients treated for tuberculosis in such countries and immediate replacement with ethambutol if there are any prodromal signs of toxicity. 

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. 

Therapy for drug-sensitive pulmonary tuberculosis consists of isoniazid (5 mg/kg, up to 300 mg/day), rifampin (10 mg/tcg/day, up to 600 mg daily), pyrazinamide (15-30 mg/kg/day or a maximum of 2 g/day), and a fourth agent, typically either ethambutol (usual adult dose cf 15 mg/kg once per day) or streptomycin (1 g daily). The streptomycin dose is reduced to 1 g twice weekly after 2 months. Pyridoxine, 15-50 mg/day, also should be included for most adults to minimize adverse reactions to isoni(K,id. Isoniazid, rifampin, pyrazinamide, and ethambutol or streptomycin are given for 2 months isoniazid and rifampin are then continued for 4 more months. Doses in children are isoniazid, 10 mg/kg/day (300 mg maximum) rifampin, 10-20 mg/kg/day (600 mg maximum) pyrazinamide, 15-30 mg/kg/day (2 g maximum). Isoniazid, rifampin, and ethambutol are considered safe during pregnancy. 

Bhatia and Merchant (43 ) reporting on a comparative study assessing treatment regimes in primary tuberculosis in children below the age of 5 years, found no adverse reactions in those children given ethambutol for periods ranging from 6-18 months. It will be interesting to see if this apparent lack of toxicity of the compound in young children is substantiated by further work. 

Nervous system The adverse effects of antituberculosis drugs on the nervous system have been reviewed [1 ]. Isoniazid is most often associated with nervous system reactions, most prominently peripheral neuropathy, psychosis, and seizures. Optic neuropathy can occur with ethambutol and ototoxicity and neuromuscular blockade with aminoglycosides. Cycloserine can cause psychosis and seizures, and the psychosis in particular limits its use. Fluoroquinolones are rare causes of seizures and delirium. Significant neurotoxicity has not been documented with newer forms of therapy under development. 

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