Individualized drug dosage in patients treated with continuous hemofiltration.

Background: Subtherapeutic drug dosing may be even more dangerous than overdosage, especially for intensive care patients requiring hemofiltration.

Proposal: According to Dettli's fundamental equation, body clearance of any drug (Cl) is a linear function of creatinine clearance (Cl = Cl anur + a x C(Cr)), with [a = (Cl norm - Cl anur)/C(Cr), norm]. We propose to individualize drug dosage during high-flux hemofiltration by basing it on Dettli's equation and on total C(Cr) (C(Cr) tot = C(Cr) ren + C(Cr) filt). Using this approach, drug clearance will eventually be overestimated for drugs with substantial tubular secretion and for high-efficiency hemofiltration (C(Cr) tot > 30 ml/min).

Conclusion: In patients undergoing hemofiltration, the total C(Cr) approach might be a practical alternative to standardized dosing schemes for deriving an individualized dosage from published pharmacokinetic data and functions.