Table 1.

Pharmacology of metformin in normal subjects and in chronic renal failure (adapted from 13,18–20)

Parameter	Normal subjects	Chronic renal failure
Bioavailability (%)	50–60	50–60
Distribution volume (L)a	500–600	–
Half-life (hours)b	3.0	4.5–13.0
Clear/F (ml/min)b	933–1317	200–850
Toxic threshold plasma level (mg/L)c	5.0	5.0
Threshold-dose (p.o mg/day)d BCrC 120 ml/min	3000	–
BCrC 60 ml/min	–	2000
BCrC 30 ml/min	–	1000
BCrC 15 ml/min	–	500

^aValues are referred to patients with type 2 diabetes mellitus with normal renal function

^bThe values are referred for oral IR formulations and to the different stage of renal failure for chronic renal failure (Ref [19, 20])

^cPlasma peak levels for XR formulation and as equal split doses for IR formulation

^dRecommended daily doses for XR formulation and as equal split doses for IR formulation. Doses in chronic renal failure are according to renal function (Ref 20)

Clear/F clearance after oral administered dose, BCrC blood creatinine clearance, IR immediate release, XR extended release