Potassium
Chemical
Potassium – Dominant intracellular cation
Use
- Hypokalaemia (refeeding, HHS, DKA)
- 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
- Main determinant of ICF osmolality (and ICF osmotic pressure and ICF tonicity) → because K+ is the main osmotic solute intracellularly
- Regulates membrane potential (RMP) of excitable cells
- Neuromuscular excitability → as determined by RMP
- Role in action potential → repolarisation phase during AP
- Secretion of insulin
- Regulation of some IC processes (protein/glycogen synthesis)
- 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