Evaluation of bioadhesive glipizide spheres and compacts from spheres prepared by extruder/marumerizer technique

The objective of this study was to attempt to deliver glipizide from spheres and compacts containing the natural polymer Carrageenan (Gelcarin, GP 812) and prepared by extruder/marumerizer technique. A second objective was to evaluate the mucoadhesive strength of the bioadhesive spheres onto the mucus membrane of rabbit. The effects of polymer, drug level, and type of spheronizing material were evaluated. All sphere formulations were compacted into tablets using a rotary Manesty B-3B machine equipped with 12/32 flat face tooling. Results show drug release from spheres and compacts decreased as the level of Carrageenan was increased. However as the level of drug was increased drug release also increased. Spheres containing Avicel PH-101 gave higher drug release than spheres of the same composition but prepared with Avicel RC-581. In general, the drug release from tablets was higher than its corresponding spheres and drug release from spheres and tablets containing Carrageenan was higher than control spheres and tablets of the same composition but without Carrageenan. Tablet formulations compacted from spheres containing Avicel RC-581 gave higher release rate constants than tablet formulations of the same composition but prepared with Avicel PH-101. The bioadhesion study showed that mucoadhesion strength between spheres and mucus membrane of the rabbit depends on the levels of polymer, drug, and type of spheronizing material. Developed bioadhesive spheres and tablets increase the solubility of glipizide which may increase its bioavailability and also increased the adherence of the bioadhesive systems to the mucous membrane so that once daily dose can be administered.