Evaluation of modified breadfruit ( Artocarpus altilis ) starches as immediate and sustained release polymers in bilayer tablets of ibuprofen

Background: Ibuprofen, administered as conventional oral tablets every 4 -6 hours, has some gastrointestinal side effects. Its formulation as sustained and immediate release layers in a compact bilayer tablet avoids the challenge of multiple daily dosing, reducing untoward side effects. Objectives: The objective of the study is to formulate bilayer tablets of ibuprofen using breadfruit ( Artocarpus altilis ) starches modified by carboxymethylation and acid hydrolysis for immediate and sustained release, respectively, in comparison to sodium starch glycolate (SSG) and hydroxypropyl methyl cellulose (HPMC). Methods: The starches were characterized using Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction (XRD) analysis, viscosity, swelling power, densities and flow properties. Bilayer tablets of ibuprofen were prepared using carboxymethylated Breadfruit starch (5.0 and 7.5%w/w) and acid-hydrolyzed starch (17.0%w/w) and evaluated using crushing strength, friability, disintegration and dissolution times (t80). Results: FTIR and XRD spectra confirmed modification of starches. Carboxymethylation produced starches of higher swelling and flow properties while acid-modification produced higher compressibility. Bilayer tablets containing modified starches had higher crushing strength than the standards. Disintegration time of the fast release layers was 1.00 - 10.37 min. An initial burst release was followed by sustained release (t80 = 4.5 - 9.0 h) with tablets containing the acid modified starch having longer dissolution than HPMC. Drug release fitted the First order, Hixson-Crowell and Hopfenberg kinetic models. Conclusion: Carboxymethylated and acid-modified breadfruit starches were found suitable as cheaper excipients in bilayer tablet formulations for immediate and sustained release of drugs respectively, particularly where high mechanical strength is required. Keywords: Acid-modification, bilayer tablets, breadfruit starch, carboxymethylation, ibuprofen