Application of a whole-body physiologically based pharmacokinetic model to describe the plasma and urine disposition of colistin and colistin methanesulfonate (CMS) in healthy volunteers

• Objectives: The primary aim of this work was to develop a whole-body physiologically based pharmacokinetic (WBPBPK) model to describe CMS and colistin disposition in human plasma and urine. The secondary aim of this analysis was to use the WBPBPK model to predict CMS and colistin tissue distribution in typical individuals with different pathophysiological changes and receiving different dosing regimens.Methods: Twelve healthy males were included in the analysis. They received a single dose of 80 mg CMS (1 million unit) through a 1-h intravenous infusion. Venous blood was collected between 0 and 18 h post dose. Fractionated urine samples were collected between 0 and 24 h after dose. A WBPBPK model initially developed in rat was further detailed with the addition of a specific urinary tract (UT) model. The Kp values of CMS and colistin were estimated for all tissues using experimental Kp prior values from rat tissue homogenates.Results: The model adequately described CMS and colistin concentrations over time in plasma and in urine. A shared first order elimination rate constant was estimated to depict the hydrolysis of CMS in plasma and tissues. A separate hydrolysis rate constant for CMS was estimated in urine, and was lower than in plasma and tissues. A shared non-renal elimination rate constant of colistin was estimated in plasma and in tissues. CMS and colistin disposition in urine was well characterized by the UT model. The tubular reabsorption of colistin was best described by a saturable model estimating the colistin affinity constant, KM. Non-specific binding of colistin in the UT lumen was accounted for using a linear relationship.Conclusion: The WBPBPK developed in this study characterized plasma and urine PK of CMS and colistin in human well. This model was used as a new framework to predict colistin exposure in the tissues of interest under different physiological conditions. The model can be easily refined when new data are available and can be combined to PKPD models to increase the understanding of the concentration-effect relationship at target sites.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Farmaceutiska vetenskaper (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Pharmaceutical Sciences (hsv//eng)

Nyckelord

colistin

CMS

WBPBPK model

PBPK

human

predictions

urinary disposition

Pharmacokinetics and Drug Therapy

Farmakokinetik och läkemedelsterapi

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)