Absorption of ipsapirone along the human gastrointestinal tract

Isapirone-HCl (5 mg) was administered orally, rectally and locally, by a remote control drug delivery device (HF-capsule) into different segments of the gastrointestinal tract, to four young healthy male adults. The relative systemic bioavailability of the drug from the colon and rectum was 2-3-fold greater than that from the upper gastrointestinal tract. This supports a rationale for a prolonged-release formulation.