What is the half-life of mannitol in a patient with normal renal (kidney) function?

Half-Life of Mannitol in Normal Renal Function

In patients with normal renal function, mannitol has an elimination half-life of 0.5 to 2.5 hours, with a distribution phase half-life of approximately 0.16 hours. 1

Pharmacokinetic Profile

Distribution Phase

• Mannitol distributes largely to the extracellular space within 20 to 40 minutes after intravenous administration 1
• The volume of distribution is approximately 17 L in adults 1
• The plasma half-life for the distribution phase is 0.16 hours 1

Elimination Phase

• The elimination half-life ranges from 0.5 to 2.5 hours in patients with normal renal function 1
• Total clearance is 87 to 109 mL/minute in subjects with normal renal function 1
• Approximately 80% of a 100 g dose appears in the urine within 3 hours 1

Renal Clearance Mechanism

• Mannitol is freely filtered by the glomeruli with less than 10% tubular reabsorption 1
• It is not secreted by tubular cells 1
• Only a relatively small amount of the mannitol dose is metabolized after intravenous administration 1

Critical Caveat: Renal Impairment

The elimination half-life is dramatically prolonged in patients with renal impairment, increasing to approximately 36 hours in those with acute or end-stage renal failure. 1, 2

Half-Life in Renal Dysfunction

• In patients with renal impairment, the elimination half-life extends to about 36 hours based on serum osmolarity 1, 2
• During hemodialysis, the half-life is reduced to 6 hours 1, 2
• During peritoneal dialysis, the half-life is reduced to 21 hours 1, 2

Clinical Implications

• Serum osmolality should be measured frequently after mannitol administration and maintained below 320 mOsm to avoid renal failure 3
• Mannitol accumulation in renal impairment can lead to severe complications including dilutional hyponatremia, hyperosmolality, and fluid overload 4, 2