Failure of absorption of gabapentin after rectal administration

We wished to determine the extent of absorption of gabapentin (GBP) after rectal administration to children on maintenance therapy.

Two children scheduled for extensive surgery received GBP rectally and orally. A pharmacokinetic profile was derived after each route of administration.

Serum GBP levels after rectal administration decreased at a rate similar to their rate of decrease after oral administration. However, GBP concentrations were much lower after rectal administration; therefore, we concluded that the aqueous solution was poorly absorbed rectally. The GBP half-life (t1/2) for the 2 children after oral doses were 4.2 and 4.8 h.

Rectal administration of GBP is not satisfactory when oral administration is interrupted. When oral GBP therapy is temporarily discontinued, clinicians should consider administration of alternative antiepileptic drugs (AEDs) that can be administered parenterally or rectally.