Ethambutol causes:
Ethambutol (E): Ethambutol is selectively tuberculostatic and clinically as active as S. Fast multiplying bacilli are more susceptible as are many atypical mycobacteria. Added to the triple drug regimen ofRHZ it has been found to hasten the rate of sputum conversion and to prevent development of resistance. The mechanism of action of E is not full understood, but it has been found to inhibit arabinosyl transferases involved in arabinogalactan synthesis and to interfere with mycolic acid incorporation in mycobacterial cell walL Resistance to E develops slowly; in many cases it is due to alteration in the drug target gene. I\o cross resistance with any other antitubercular drug has been noted. Loss of visual acuity / colour vision. field defects due to optic neuritis is the most impoant dose and duration of therapy dependent toxicity. Because young children ma,be unable to repo early visual impairment, it should not be used below 6 years of age. With early recognition and stoppage of therapy, visual toxicity is largely reversible. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:742
Retrobulbar neuritis
Deafness
Red urine
Peripheral neuritis
Chemotherapy