Table 3.

Main alterations in drug PK in patients with CKD

PK characteristics	Alterations in CKD
Bioavailability	Decreased absorption (alkaline media, reduced peristalsis, bowel oedema, and phosphate chelation) Altered first pass (decreased biotransformation of parent drug and impaired protein binding resulting in more free drug available for liver)
Volume of distribution	Increased volume of distribution or extracellular volume overload Decreased volume of distribution in muscle wasted patients
Protein binding	Increased or decreased protein binding with a correspondent decrease or increase in free (active) drug concentration Low albumin increases active drug Organic acids accumulate in renal failure and compete with acid drugs for protein binding
Drug metabolism/renal elimination	Drug metabolism could be modified and unpredictable (increased or decreased) Non-renal elimination could be compensatory increased resulting in higher concentrations of potential toxic metabolites Parent compound could accumulate in CKD