An in vitro in vivo investigation of oral bioadhesive controlled release furosemide formulations

The in vitro controlled release and bioadhesive properties of furosemide formulations were evaluated with standard dissolution tests and with a specially developed model using rabbit intestine. The results showed that the controlled release properties were not affected by the application of the bioadhesive polymer but that the bioadhesive properties were substantially different. In order to assess the gastrointestinal transit time in vivo, a gamma-scintigraphy study was performed in six volunteers testing the same controlled release formulation with and without bioadhesive polymer. Plasma levels of furosemide, evaluation of urinary flux and measures of urinary excretion of furosemide in the six volunteers allowed correlations to be made between gastrointestinal transit and furosemide absorption. (C) 1997 Elsevier Science B.V.