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

Abstract

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