Relative bioavailability of lamotrigine chewable dispersible tablets administered rectally

Area of Science:

• Pharmacokinetics
• Drug bioavailability
• Rectal drug delivery

Background:

• Lamotrigine (LTG) is an antiepileptic drug.
• Alternative routes of administration are explored for patient convenience and adherence.
• Rectal administration offers potential benefits in specific clinical scenarios.

Purpose of the Study:

• To evaluate the relative bioavailability of lamotrigine (LTG) when administered rectally using chewable dispersible tablets.
• To compare rectal absorption of LTG to oral administration.

Main Methods:

• A two-period crossover study was conducted in 12 healthy adult volunteers.
• Participants received 100 mg of LTG chewable dispersible tablets orally and rectally, with a 2-week washout period.
• Plasma LTG concentrations were measured up to 120 hours post-administration and analyzed using high-performance liquid chromatography.

Main Results:

• Lamotrigine (LTG) was absorbed following rectal administration.
• Plasma drug concentrations were lower after rectal administration compared to oral administration.
• The relative bioavailability (AUC(rectal)/AUC(oral)) of rectally administered LTG was determined to be 0.52 ± 0.23.

Conclusions:

• Rectal administration of lamotrigine (LTG) from chewable dispersible tablets results in systemic absorption.
• The extent of absorption via the rectal route is less than that achieved with oral administration.
• Rectal administration of a suspension prepared from these tablets can be considered an acceptable alternative route for lamotrigine delivery.