Renal impairment - Compared with patients with normal renal function (creatinine clearance > 80 ml/ min), plasma clearance is 1.2 to 1.4 times lower in patients with mild renal impairment (creatinine clearance 50 to 80 ml/ min) and on average 2 times lower in patients with moderate renal impairment (creatinine clearance 30 to 50 ml/ min).