Comparative Evaluation of Single-Polymer and Optimized Gastro-Retentive Matrix Tablets of Lornoxicam

Abstract

Gastro-retentive drug delivery systems are developed to increase gastric residence time and sustain drug release for enhanced drug absorption and therapeutic performance. Natural polymers have great potential as floating matrix tablets because of their swelling, gel-forming and matrix retarding properties. The present study was designed to compare the performance of single-polymer and optimized multi-polymer gastro-retentive floating matrix tablets of Lornoxicam and to investigate the synergistic effect of Okra mucilage, Xanthan gum and Chitosan on floating behavior, swelling, matrix integrity and sustained drug release. Lornoxicam floating matrix tablets containing Okra mucilage, Xanthan gum or Chitosan as individual matrix-forming polymers were prepared by direct compression. The formulations were examined for pre-compression and post-compression characteristics (buoyancy lag time, swelling index, drug content), in vitro drug release. An optimized multi-polymer formulation (F18) with a combination of Okra mucilage, Xanthan gum and Chitosan was compared with the individual polymer formulations under similar experimental conditions. The single-polymer formulations had their own functional advantages. Okra mucilage had good hydration and swelling capacity; Xanthan gum floating properties and sustained release behavior; Chitosan matrix integrity and tablet strength but none of the individual polymers provided an optimum balance of all performance attributes. F18 (optimized multi-polymer formulation) showed superior overall performance with a swelling index 281.6%, drug content 99.56% buoyancy lag time only 24 s, controlled and sustained drug release (cumulative drug release 98.64% at 12 h). The improved performance of F18 was due to complementary and synergistic effects of three natural polymers on hydration, matrix formation, floating ability and drug-release control. The comparative results show that Okra mucilage, Xanthan gum and Chitosan are better than individual polymers for Lornoxicam gastro-retentive floating matrix tablets development. Optimized multi polymer system is promising for prolonged gastric retention and sustained drug delivery.