The absorption pattern of orally administered OxyContin (OXC) reflected in urine indicates that its appearance into systemic circulation undergoes transit absorption delays. The authors developed an OXC transit-delay compartment model that identified a new source of oxycodone hydrochloride (OC): the rate of appearance of OC due to OXC tablet dissolution in transit through the gastrointestinal (GI) tract (R(a)(GI)), which is due to disintegration of OXC's AcroContin delivery system. R(a)(GI) is independent of the biphasic dissolution and release of OC from the delivery system. The authors conclude that an OXC transit-delay compartment model can be of value in the interpretation of OXC pharmacokinetics.
Keywords: OxyContin; mathematical modeling; noroxycodone; oxycodone; oxymorphone; pharmacokinetics; transit-delay compartment model; urine.