Potassium

Chemical

Potassium – Dominant intracellular cation

Use

  1. Hypokalaemia (refeeding, HHS, DKA)
  2. Post cardiac surgery to decrease risk of cardiac arrhythmias

Presentation

Oral formulation

  • Potassium chloride modified release tablets 600mg – 8mmol/tablet
  • Potassium chloride effervescent 14mmol/tablet 

IV formulation – KCl ampoules containing 10mmol KCl in 10mls

  • 10 mmol KCl in 100mls NaCl 0.29% 
  • 20mmol KCl in 100mls NaCl 0.9% 
  • 20mmol KCl in 50mls NaCl 0.9%/dextrose 5%
  • 30mmol KCl in 1L NaCl 0.9%/dextrose 5%/Hartmann’s
  • 10mmol KH2PO4 in 275mls NaCl 0.9%

Dose

10-20mmol 

Titrate to therapeutic range 3.5-5.2 mmol/L

Oral or IV or IV infusion

>10mmol/hr (requires cardiac monitoring)

Route

Oral – modified release tablets/effervescent tablet

CVC – 20mmol KCl in 50mls NaCl 0.9%/dextrose 5% over 60 mins

Onset

Immediate

MoA

Dissociates to provide K+

Potassium important in carbohydrate utilisation, protein synthesis, regulation of nerve and muscle contraction, Na/K ATPase 

PD

  1. Main determinant of ICF osmolality (and ICF osmotic pressure and ICF tonicity) → because K+ is the main osmotic solute intracellularly
  2. Regulates membrane potential (RMP) of excitable cells
  3. Neuromuscular excitability → as determined by RMP
  4. Role in action potential → repolarisation phase during AP
  5. Secretion of insulin
  6. Regulation of some IC processes (protein/glycogen synthesis)
  7. Involved in Na+/K+ ATPase in cell membranes

PK

A

NA

D

10% remain extracellular

M

NA

E

Excreted via kidneys (chiefly regulated by aldosterone), sweat & GIT loss in faeces

Adverse Effects

Phlebitis 

Hyperkalemia

High risk of asystole if administration rate >40mmol/hr

Caution in severe renal impairment, acute dehydration, extensive tissue injury/burns, AV block with digoxin, potassium aggravated skeletal muscle channelopathies

Drug Interactions

Amphotericin, insulin infusion, high dose co-trimoxazole 

Author: Novia Tan / Huiling Tan