6.5 Elimination by route of exposure
During the 24-hour period following oral administration
of ethambutol, approximately 50% of the initial dose is
excreted unchanged in the urine, while an additional 8% to
15% appears in the form of metabolites. From 20 to 22% of
the initial dose is excreted in the faeces as unchanged drug
(PDR, 1989).
No drug accumulation has been reported with consecutive
single daily doses of 25 mg/kg in patients with normal kidney
function, although marked accumulation has been demonstrated
in patients with renal insufficiency (PDR, 1989).
The intrinsic total body clearance is 9 mL/min/kg (Gilman et
al., 1990).