Modified‐release systems have been evaluated as an option to formulations that employ the conventional delivery system and, therefore, may present side effects and reduced therapeutic efficacy. In general, it is more convenient to modify the release of existing drugs to overcome their drawbacks, since developing a new drug can be a quite expensive and time‐consuming process. Furosemide, a drug for hypertension treatment, when administered in the conventional form, can cause inconvenience to patients due to short and intense periods of diuresis and the need for multiple daily administrations due to its short half‐life. In order to modify its release, in the present work, furosemide was successfully incorporated into sericin/alginate matrix prepared by ionic gelation and modified by thermal or covalent cross‐linking, through the addition of proanthocyanidin, achieving high incorporations rates. This polymeric matrix provided a delayed and sustained release form for furosemide, which could improve patients' compliance to treatment and decrease its side effect. Furosemide release study demonstrated that the cross‐linking method affects the amount of dosage release and does not affect the release time, but the presence of sericin does. scanning electron microscopy, X‐ray diffraction, and FT‐IR analyses confirmed furosemide incorporation. The drug thermal stability was not affected by its incorporation and the particle size was considered suitable for multiparticulate system.

A furosemida é um fármaco que em doses altas leva à diurese rápida e intensa. Neste estudo investigou-se a incorporação de furoseminda em blenda de sericina e alginato em diferentes concentrações, a fim de modificar a liberação do fármaco, diminuindo assim os efeitos colaterais causados por ele. Foram realizados testes de dissolução, e caracterização da blenda com fármaco incorporado por microscopia ótica e difração de raios X.

BACKGROUND Most drugs are designed for immediate release via oral administration, releasing the dosage rapidly. Those administration forms can present a wide variation in drug concentrations, which can be harmful to a patient, when the amount of drug is either below or above the therapeutic range. Modified‐release formulations promise to alleviate the problems inherent to immediate‐release drugs by modifying their form of encapsulation. A sericin/alginate blend was applied as a matrix to modify the release of furosemide. The influence of furosemide and alginate concentration was evaluated in the incorporation efficiency and release time of 85% of drug content using a 22 full‐factorial experimental design. Various analytical techniques were employed to characterize the produced drug particles. RESULTS The incorporation efficiencies ranged from 73.4 ± 2.1% to 84.7 ± 2.9% and the release could be classified as delayed and sustained due to gastroresistance of the particles and a longer release time compared to the commercial drug. Release mechanism was controlled by the relaxation of macromolecular chains due to absorption of water by the particles and the erosion of the matrix. The presence of furosemide crystals was confirmed. Furosemide thermal stability was not altered with its incorporation into the sericin/alginate blend and mean diameter was small enough that the particles could be applied to multiparticulate systems. CONCLUSIONS Sericin/alginate blend could serve as a biodegradable and biocompatible matrix for furosemide incorporation for delayed and sustained drug delivery. © 2020 Society of Chemical Industry (SCI)