Absorption and dissolution of nitrofurantoin from different experimental formulations

The general applicability of the polyvinylpyrrolidone, polyethylene glycol, mannitol and sorbitol solid dispersion and co-precipitation technique as a method for enhancing the gastrointestinal absorption of orally administered hydrophobic drugs was explored with the urinary antiseptic nitrofurantoin. The in vivo absorption patterns of pure nitrofurantoin and the test preparations were compared by following the cumulative amount of nitrofurantoin excreted in the urine as a function of time. The results of these urinary excretion studies demonstrated that the absorption of nitrofurantoin in man from the test systems was significantly enhanced and was present in the body at much higher levels than when equivalent doses of either the drug alone or as physical mixture were orally administered. A correlation was found between the in vitro dissolution rates of these test systems at 37°C and their in vivo absorption data.