Eating does not modify benoxaprofen blood concentrations. Combining benoxaprofen with tolbutamide does not significantly change plasma glucose, insulin, or tolbutamide concentrations. Probenecid, by blocking renal tubular secretion of benoxaprofen, increases the benoxaprofen half-life and decreases its renal clearance and urinary excretion. Excretion rate is halved in patients with severe renal impairment. Hemodialysis inefficiently lowers benoxaprofen plasma concentrations. Neither glomerular nor renal tubular function is affected by benoxaprofen, even after five years of therapy. The incidence in urine of microscopic spheroids (benoxaprofen glucuronide complexes) is related to urinary drug concentration and osmolality; increasing the fluid intake decreases incidence.