From the Guidelines
Ketamine works in seizures by blocking NMDA receptors in the brain, which reduces excessive neuronal activity that contributes to seizures. As an NMDA receptor antagonist, ketamine decreases glutamate's excitatory effects, helping to stabilize the electrical activity in the brain during seizure activity 1. The exact mechanism of ketamine in seizures is not fully understood, but it is thought to involve the inhibition of glutamate release and the blockade of NMDA receptors, which are involved in the regulation of neuronal excitability.
Some key points to consider when using ketamine for seizures include:
- Ketamine is typically used at doses of 0.5-4.5 mg/kg IV for status epilepticus when first and second-line agents have failed 1.
- It can be administered as a bolus followed by continuous infusion at 0.3-5 mg/kg/hour, with the dose adjusted based on clinical response.
- Ketamine is particularly valuable in refractory status epilepticus because it works through a different mechanism than traditional anticonvulsants like benzodiazepines and phenytoin.
- Additionally, ketamine maintains cardiovascular stability better than many other anesthetic agents used for seizure control.
- However, it should be used with caution due to potential side effects including increased intracranial pressure, hallucinations, and emergence reactions.
- Monitoring of vital signs, neurological status, and EEG when possible is essential during ketamine administration for seizure management.
It's worth noting that the provided evidence does not directly address the use of ketamine in seizures, with the exception of the study published in the Annals of Emergency Medicine 1. The other study provided focuses on the use of ketamine as a potential rapid-acting antisuicidal agent 1, and is not directly relevant to the question of how ketamine works in seizures. Therefore, the recommendation is based on the most recent and highest quality study available, which is the 2014 study published in the Annals of Emergency Medicine 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Mechanism of Action
- Ketamine is a noncompetitive N-methyl-D-aspartate (NMDA) antagonist, which means it blocks the action of glutamate at NMDA receptors 2, 3.
- This mechanism is thought to be responsible for its antiseizure effects, as NMDA receptors are overexpressed in prolonged status epilepticus 3.
- Ketamine's ability to block NMDA receptors makes it a potential treatment option for refractory status epilepticus (RSE), which is resistant to traditional antiepileptic drugs 3, 4.
Efficacy in Seizure Management
- Studies have shown that ketamine is effective in controlling seizures in patients with RSE, with some reports showing complete seizure control 5, 4.
- Ketamine has been used in combination with other antiepileptic drugs to achieve adequate control of seizures, and has been shown to be safe and efficacious in this setting 4, 6.
- The use of ketamine in the prehospital setting has also been explored, with potential benefits including early treatment of status epilepticus and reduced risk of hemodynamic or airway collapse 5.
Dosage and Administration
- The dosage of ketamine used in seizure management varies, with reports ranging from 0.45 mg/kg/h to 2.1 mg/kg/h 4.
- Ketamine can be administered as a continuous infusion, and has been used in combination with other antiepileptic drugs to achieve adequate control of seizures 4, 6.
- The transition from intravenous to enteral formulation of ketamine has also been described, with potential benefits including shortened length of stay in the intensive care unit and hospital 2.