From the Guidelines
Keppra distributes rapidly in the bloodstream, reaching peak plasma concentrations within 1 hour after oral administration and within 30 minutes to 1 hour after intravenous administration.
Key Points
- The bioavailability of Keppra is nearly 100% when taken orally, allowing almost all of the drug to enter the bloodstream 1.
- Keppra has minimal protein binding (less than 10%), enabling it to distribute freely throughout the body, including across the blood-brain barrier to reach its target sites in the central nervous system.
- The drug achieves steady-state concentrations after 2 days of typical twice-daily dosing.
- The volume of distribution is approximately 0.5-0.7 L/kg, indicating that the drug distributes primarily in total body water rather than accumulating in fatty tissues.
- According to the study published in the Annals of Emergency Medicine 1, a 1,500 mg oral load of Keppra can be administered, and rapid IV loading is safe and well-tolerated in doses up to 60 mg/kg.
Distribution and Onset of Action
The rapid distribution of Keppra contributes to its relatively quick onset of action for seizure control, though full therapeutic effects may take longer to develop.
- The study 1 provides information on the loading dose and route of administration strategies for antiepileptic medications, including Keppra.
- The choice of administration route (oral versus parenteral) is at the discretion of the emergency physician, as there is a lack of evidence to support one route over the other in terms of preventing early recurrent seizure 1.
From the FDA Drug Label
Absorption of levetiracetam is rapid, with peak plasma concentrations occurring in about an hour following oral administration in fasted subjects. The distribution of Keppra (levetiracetam) in blood is rapid, with peak plasma concentrations reached in approximately 1 hour after oral administration in fasted subjects 2.
From the Research
Distribution of Keppra in Blood
- The distribution of Keppra (levetiracetam) in blood is characterized by its rapid absorption, with peak concentration occurring after 1.3 hours 3.
- Keppra has a bioavailability of >95%, and its absorption is not affected by food, although food can slow the rate of absorption 3.
- The plasma concentrations of Keppra increase in proportion to the dose, and there is no evidence of accumulation during multiple administration 3.
- Steady-state blood concentrations of Keppra are achieved within 24-48 hours 3.
- Keppra is not bound to plasma proteins and has a volume of distribution of 0.5-0.7 L/kg 3.
Comparison with Other Antiepileptic Drugs
- Keppra has a more favorable pharmacokinetic profile compared to other antiepileptic drugs, such as gabapentin, which has a slower absorption rate and lower bioavailability 4, 3.
- Keppra's pharmacokinetic characteristics are similar to those of pregabalin, which also has a rapid absorption rate and high bioavailability 4, 5.