Preparation and characterization of crosslinked starch-albumin films for coating of prednisolone tablets for use in Covid-19 related respiratory disease

Steroidal products have been found useful in inflammations associated with Covid 19. Prednisolone is one readily available steroid, which is often found as uncoated normal release tablets. Modified release prednisolone may be desirable in Covid 19 for sustained actions. This is expected to reduce dosing frequency and enhance compliance. This study is concerned with development of controlled release prednisolone using coating technology with bio-compatible, cross-linked starch-albumin films. Starches and proteins are excellent film formers with good flexibility, transparency, and bio-compatibility. The cross-linked starch-albumin films were prepared using glycerol as the plasticizer: starch (A), starch-albumin (B), starch-albumin cross-linked with formaldehyde at 1 % (C), 5 % (D) and 10 % (E). Equilibrium moisture sorption (EMS) at 100 % relative humidity, equilibrium swelling (ESC) in buffer solutions of pHs 2, 7 and 9, and DSC thermal properties were evaluated. In-vitro drug release from the film coated prednisolone tablets were evaluated in 0.1N HCl, water and phosphate buffer 8.0 as dissolution media. Films showed ESC in the order A>D>E>B>C; D>C>A>E>B and A>D>C>B>E in acidic, neutral and alkali media respectively. EMS was in the order B>E>A>D>C; with slight shift in the melting temperatures. In-vitro release at 240 min varied from 78 to 117 % (E>D>C>A>B); 19 to 60 % (D>B>C>E>A) and 49 to 60 % (B>A>C>D>E) in 0.1N HCl, water and PBS respectively. Cross-linking improved the stability and swelling of films. The in-vitro release in alkaline medium suggests their usefulness for controlled drug delivery. New pH-responsive polymers, with improved physicochemical properties for coating prednisolone tablets were developed.