Abstracts

Rectal administration of AEDs offers a beneficial route of administration for patients who are unable to take medications orally and an IV route is not available. To date, no case reports of rectal administration of levetiracetam (LEV) have been published. The purpose of our review is to report our findings on rectal absorption of LEV in an adult and a pediatric patient. Inpatient charts for both patients were retrospectively reviewed for LEV dosing, LEV concentrations, administration procedures, weight and complications. LEV concentrations were analyzed by MedTox Labs, MN for Case 1 and Mayo Labs, MN for Case 2. CASE 1: 56 yr old male in the ICU for frequent seizures was intubated and receiving medications IV or via feeding tube. LEV on admission was 1500mg per tube BID at 0800, 2200; trough level (16.8 mg/L). LEV was increased to 2000mg BID on Day 2. Beginning on day 8, due to poor tolerance of tube feedings, LEV was administered rectally at the same dose for 8 days. A series of 6 LEV levels was obtained surrounding the first rectal dose at -1, 1, 2, 3, 6 and 11 hours post administration. Results as follows: 36.8 mg/L, 42.6 mg/L, 36.1 mg/L, 35.6 mg/L, 31.5 mg/L, 25.1 mg/L, respectively. A trough level prior to the 4^th dose of rectal LEV was 16.4 mg/L. LEV administration was changed back to feeding tube administration 2000mg BID with one steady state trough LEV level obtained (49.5 mg/L, Day 27). Another steady state trough level on 1750mg BID per feeding tube was obtained on Day 55 (32.4 mg/L). LEV suspension was administered undiluted and the buttocks held for 30 minutes. No seepage was noted. Irritation could not be assessed.
CASE 2: 16 month old male with uncontrolled focal seizures and multiple benzodiazepine loads was started on LEV 250mg (21 mg/kg) per rectum x1. A one hour post dose level was obtained (6.6 mg/L). LEV continued at 100mg (8.5 mg/kg) BID oral/rectal with doses 2 and 3 administered rectally. On 200mg (17 mg/kg) po BID, a steady state trough LEV=4.5 mg/L. LEV suspension was administered undiluted and the buttocks held for 5 minutes. Seepage was questionable per RN after the first dose, but not identified with doses 2 or 3. Irritation could not be assessed. Levetiracetam was administered rectally in two patients. These data confirm that LEV is absorbed with rectal administration. However, steady state trough concentrations may be decreased more than 50% compared to feeding tube administration at the same dose. These preliminary data suggest a dosing ratio adjustment of approximately 2:1 for rectal administration of LEV may be necessary.