In end of life care, often times the oral route of medication administration is not an option. However, it is important that seizure prophylaxis be maintained beyond the patient's ability to swallow and that treatment options are known. The good news about rectal administration of seizure medications is that many antiepileptics that patients take orally can be given rectally. In addition, the dosages of these medications do not need adjusted from oral to rectal.
Phenobarbital is one of the oldest medications used for seizure prophylaxis. This medication is weight based and also takes 4-5 hours to reach peak concentration. For that reason, phenobarbital should not be used for acute seizure episodes. Dosages are most often 1-3mg/kg orally or rectally in divided doses (1-2 times daily). Note phenobarbital is sedating.
Carbamazepine immediate release tablets can be used rectally. Ideally, the same daily oral dosage is given rectally in 6-8 small, divided doses and the crushed tablets are put in a gelatin capsule when possible. Most patients require daily doses between 800-1200mg. Note carbamazepine serum concentrations should be monitored. Carbamazepine suspensions can also be used and would need to be diluted with an equal volume of water.
Valproic acid and divalproex sodium are of the most commonly used medications for seizure prophylaxis. Fortunately, they too can be used rectally when oral administration is not possible. If using the liquid formulations, dilute with an equal volume of water. Optimal response is seen at doses below 60mg/kg/day, in divided doses.
Lastly, a lamotrigine rectal suspension can be prepared out of the immediate release or chewable tablets. This is done by crushing the tablets and mixing into 6-10mL of room temperature water. Most patients find success at a dose of 250mg twice daily.
Benzodiazepines such as diazepam and lorazepam are commonly used rectally for acute seizures and should not be excluded from this overview.
There are many reasons that a patient may need to be on an antiepileptic drug: epilepsy, brain metastases, and even disease progression, to name a few. Using the above information, management of these medications beyond the oral route is possible and dose conversions are not necessary.
1. Connelly, J., & Weissman, D. Fast Fact #229: Seizure Management in the Dying Patient. Retrieved September 4, 2015, fromhttps://www.capc.org/fast-facts/229-seizure-management-dying-patient/
2. Krouwer H, Pallagi J, Graves N. Management of seizures in brain tumor patients at the end of life. J Palliat Med. 2000;3:465-475