Which of the following antitubercular drug is preferred in severe liver disease?

STREPTOMYCIN It is the oldest aminoglycoside antibiotic obtained from Streptomyces griseus.It is used in tb. M ECHANISM O F ACTION: The aminoglycosides are bactericidal antibiotics, all having the same general pattern of action which may be described in two main steps: (a) Transpo of the aminoglycoside through the bacterial cell wall and cytoplasmic membrane. (b) Binding to ribosomes resulting in inhibition of protein synthesis. 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 of RHZ it has been found to hasten the rate of sputum conversion and to prevent development of resistance. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:742,722