Abstract
Mebeverine Hydrochloride (MB-HCl), an effective spasmolytic drug, was formulated as CODES™. A colon-specific drug delivery technology CODES™ was designed to avoid the inherent problems associated with pH- or time-dependent systems. To achieve more protection and control of drug release, MB-HCl was prepared as microspheres and compressed as core tablets of CODES™ (modified CODES™). The core tablets contained the drug either in free form [Formula 1 (F1)], or as microspheres with 2 different polymer:drug:lactulose ratios (1:1:0.5 [Formula 2 (F2)] and 2:1:0.5 [Formula 3 (F3)]. The release profiles of the coated CODES™ systems were compared with uncoated compressed tablets. The uncoated tablet showed a drug release of 94% after 1 h in simulated gastric condition (pH = 1.2). The release characteristics of the coated systems revealed that the enteric coating (Eudragit®L100) prevented any drug release in simulated gastric or duodenal conditions in the first 3 h (pH 1.2-6.1), after which drug was slightly liberated in simulated intestinal fluid (pH 7.4) {Phase 1 (P1)}. After 4 h the pH was adjusted to 7 and β-glucose-oxidase was added, which is an enzyme produced by enterobacteria present in the colon. The acid-soluble coat (Eudragit®E100) dissolved and the drug release suddenly increased to reach 95, 72 and 60.4% for F1-F3, respectively. IR spectrum study showed a covalent bond between the drug and the polymer in the formulae F2 and F3 resulting in the sustained drug release from the microspheres with a significant difference (p>0.05) to F1. The findings were confirmed by in vivo investigation using X-ray images for Guinea pigs ingested tablets containing barium sulphate (F4), where the tablet began to disintegrate after 10 h of tablet intake. The results of the study indicated that MB-HCl CODES™ colon-specific drug delivery can act as a successful trigger for drug targeting in the colon. Furthermore, a sustained release of the drug can be achieved from modified CODES containing the drug in the form of microspheres.