Pharmacotherapeutic group: Solutions affecting the electrolyte balance
ATC vet code: QB05BB01.
Pharmacodynamic properties
Isotonic crystalloid solutions are for vascular filling and electrolyte replacement. They have an ionic composition very close to the extracellular fluid.
Sodium is the major cation of extracellular fluid. It is responsible for maintaining the volume of liquid and extracellular osmolarity. Potassium is mainly an intracellular cation. 99% of calcium is present in the skeleton. Chloride is essentially an extracellular anion. Lactate produces bicarbonate salts (hence its alkalising effect).
Pharmacokinetic particulars
The solution diffuses into the extracellular space whose volume is increased accordingly. The lactate ion is rapidly metabolised by the liver where it is converted to pyruvate used in the Krebs cycle with production of bicarbonates.