Background: The loop diuretic drug furosemide is widely used for the treatment of edema in
various conditions, such as pulmonary, cardiac and hepatic edema, as well as cardiac infarction. Furosemide,
due to its poor water solubility and low bioavailability after oral administration of conventional
dosage form, is categorized as class IV in the biopharmaceutical classification system.
Objective: In the case of furosemide, this release profile is responsible for various physiological problems,
acute diuresis being the most serious. This adverse effect can be circumvented by the modified
release of furosemide from tablet formulations compared to those forms designed for immediate release.
Methods: In this report, a D-optimal combined experimental design was applied for the development of
furosemide containing bilayer and compression coated tablets, aiming at lowering the drug’s burst release
in the acidic environment of the stomach. A D-optimal combined design was selected in order to
include all requirements in one design with many levels for the factors examined. The following responses
were selected as the ones reflecting better criteria for the desired drug release: dissolution at 120
min (30-40%), 300 min (60-70%) and 480 min >95%. The new formulations, suggested by the Doptimal
combined design, incorporated different grades of Eudragit ® polymers (Eudragit® E100 and
Eudragit® L100-55), lactose monohydrate and HPMC K15M. The dissolution profile of furosemide
from these systems was probed via in vitro dissolution experiments in buffer solutions simulating the
pH of the gastrointestinal tract.
Results: The results indicate that the use of Eudragit® E100 in conjunction with lactose monohydrate
led to 21.32-40.85 % drug release, in the gastric medium, in both compression-coated and bilayer tablets.
This is lower than the release of the mainstream drug Lasix® (t=120 min, 44.5% drug release), implying
longer gastric retention and drug waste minimization.
Conclusion: Furosemide’s release in the intestinal environment, from compression coated tablets incorporating
Eudragit® L100-55 and HPMC K15M in the inner core or one of the two layers of the bilayer
tablets, was delayed, compared to Lasix®.