Dialyzable drugs

Background

The ability to successfully dialyze a drug depends on: molecular size, protein binding, volume of distribution, and plasma clearance.

Molecular weight

smaller molecular weight substances will pass through the dialysis membrane more easily than larger molecular weights.

Protein Binding

Drugs with a high degree of protein binding will have a small plasma concentration of unbound drug available for dialysis, making them poorly dialyzable or requiring multiple sessions.

Volume of Distribution

Drugs with large volumes of distribution usually due to lipid solubility and low plasma protein binding are poorly diliazable.

Plasma clearance

Although plasma clearance may be beneficial, increasing plasma clearance will dcrease dialysis clearance.

Dialysis Flow Rates

Greater degrees of dialysis can be achieved with faster dialysate flow rates if the dialysate drug concentrations is low. As the concentration of drug is increased in the diasylate the flow rate needs to be lowered. B - Barbiturates

L - Lithium

I - Isoniazid

S - Salicylates

T - Theophyline/Caffeine (both are methylxanthines)

M - Methanol

E - Ethylene glycol

D - Depakote

Others - Carbamezepine

Source

• University of Buffalo Emergency Medicine Inservice Review