Neutron activation-based gamma scintigraphy in pharmacoscintigraphic evaluation of an Egalet constant-release drug delivery system.
This paper is a report from a pharmacoscintigraphic study with an Egalet constant-release system containing caffeine and natural abundance samarium oxide. First the formulation was tested in vitro to clarify integrity during irradiation in the nuclear reactor. Then six healthy male volunteers were enrolled into the in vivo study. The in vitro release of caffeine obeyed all the time linear zero-order kinetics. The in vivo release of radioactive Sm2O3 consisted of three consequent linear phases with different slopes. The release rate was fastest while the product was in the small intestine and slowest when the product was in the descending colon. In terms of the bioavailability of caffeine, the most important factor seemed to be the residence time in the ascending and transverse colon. A long residence time in these sections led to high AUC values for caffeine.
Division of Biopharmaceutics and Pharmacokinetics, Faculty of Pharmacy, FI-00014 University of Helsinki, Finland. janne.marvola@helsinki.fi
Janne
J
Marvola
Hanna
H
Kanerva
Lillian
L
Slot
Maija
M
Lipponen
Tommi
T
Kekki
Heikki
H
Hietanen
Sirpa
S
Mykkänen
Kari
K
Ariniemi
Kai
K
Lindevall
Martti
M
Marvola
D000328:Adult; D019540:Area Under Curve; D001682:Biological Availability; D002110:Caffeine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D002626:Chemistry, Pharmaceutical / Q000295:instrumentation; D003692:Delayed-Action Preparations / Q000008:administration & dosage* / Q000493:pharmacokinetics; D041981:Gastrointestinal Tract / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D009501:Neutron Activation Analysis / Q000379:methods*; D010087:Oxides / Q000008:administration & dosage / Q000493:pharmacokinetics; D011868:Radioisotopes; D011877:Radionuclide Imaging / Q000379:methods*; D012493:Samarium / Q000008:administration & dosage / Q000493:pharmacokinetics; D019820:Xanthine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics
D003692:Delayed-Action Preparations; D010087:Oxides; D011868:Radioisotopes; D019820:Xanthine; D002110:Caffeine; D012493:Samarium; C120592:samarium oxide