1. COLON SPECIFIC DRUG DELIVERY FOR MEBEVERINE HYDROCHLORIDE Fig ( 3 ): IR spectrum of: (A) Eudragit E 100,, (B) lactulose, (C) mebeverine HCl, (D) microspheres (1:1:0.5), (E) microspheres (2:1:0.5) A B C E D 4000 350030002500200015001000500 cm -1 A B Fig ( 2 ): A- (MB-HCl) Microspheres (ratio 1:1:0.5) B- (MB-HCl) Microspheres (ratio 2:1:0.5) Samia Omar 1, Basmah Al Dossary 2, Hanan Refai 3, Omaimah Al Gohary 2 1. Department of Pharmaceutics, Faculty of Pharmacy, Helwan University, Cairo, Egypt 1. Department of Pharmaceutics, Faculty of Pharmacy, Helwan University, Cairo, Egypt 2. Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, KSA 2. Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, KSA 3. Department of Pharmaceutics, Faculty of Pharmacy, Cairo University, Cairo, Egypt Mebeverine Hydrochloride (MB-HCl) as an effective spasmolytic drug was formulated as a CODES TM. The core tablet containing lactulose and the drug in free form {formula 1 (F 1 )}, or as microspheres with 2 different polymer :drug :lactulose ratios (1:1:0.5 and 2:1:0.5) {formula 2 (F 2 ) and formula (F 3 )} respectively. The core was coated by Eudragit  E 100 which was then coated by Eudragit  L 100. The release profiles of the coated CODES TM systems were compared with uncoated compressed tablets. The uncoated tablet showed a drug release of 93% after 1 hour in simulated gastric condition (pH 1.2). The release characteristics of the coated systems revealed that the enteric coating prevented any drug release in simulated gastric or duodenal conditions in the first 3 hours (pH 1.2 - 6.1), drug was slightly liberated in simulated intestinal fluid (pH 7.4) {phase 1 (P 1 )}. After 4 hours pH was adjusted at 7 and ß-glucose-oxidase was added, which is an enzyme produced by enterobacteria present in the colon. The drug release suddenly increased to reach 95%, 72% and 60.4% for F 1, F 2 and F 3, respectively. This result was confirmed with the I.R. spectrum study. Where, a covalent bond with a double bond of the polymer was formed probably with the drug resulting in the sustained drug release from the microspheres with a significant difference (p> 0.01) for MB-HCl released from CODES TM and CODES TM prepared from microspheres. This colon-specific drug delivery technology was confirmed by the in vivo investigation, using X-ray images for guinea pigs, where the tablet began to disintegrate after 10 hrs of tablet swollen. The results of our study show that Mebeverine Hydrochloride CODES TM colon-specific drug delivery can act as a successful trigger for drug release in the colon from specially coated tablets containing microspheres. Mebeverine Hydrochloride (MB-HCl) as an effective spasmolytic drug was formulated as a CODES TM. The core tablet containing lactulose and the drug in free form {formula 1 (F 1 )}, or as microspheres with 2 different polymer :drug :lactulose ratios (1:1:0.5 and 2:1:0.5) {formula 2 (F 2 ) and formula (F 3 )} respectively. The core was coated by Eudragit  E 100 which was then coated by Eudragit  L 100. The release profiles of the coated CODES TM systems were compared with uncoated compressed tablets. The uncoated tablet showed a drug release of 93% after 1 hour in simulated gastric condition (pH 1.2). The release characteristics of the coated systems revealed that the enteric coating prevented any drug release in simulated gastric or duodenal conditions in the first 3 hours (pH 1.2 - 6.1), drug was slightly liberated in simulated intestinal fluid (pH 7.4) {phase 1 (P 1 )}. After 4 hours pH was adjusted at 7 and ß-glucose-oxidase was added, which is an enzyme produced by enterobacteria present in the colon. The drug release suddenly increased to reach 95%, 72% and 60.4% for F 1, F 2 and F 3, respectively. This result was confirmed with the I.R. spectrum study. Where, a covalent bond with a double bond of the polymer was formed probably with the drug resulting in the sustained drug release from the microspheres with a significant difference (p> 0.01) for MB-HCl released from CODES TM and CODES TM prepared from microspheres. This colon-specific drug delivery technology was confirmed by the in vivo investigation, using X-ray images for guinea pigs, where the tablet began to disintegrate after 10 hrs of tablet swollen. The results of our study show that Mebeverine Hydrochloride CODES TM colon-specific drug delivery can act as a successful trigger for drug release in the colon from specially coated tablets containing microspheres. Enteric Coating Eudragit L 100 In Stomach HPMC Coating Acid-soluble Coating (Eudragit E100) In Small Intestine Lactulose Organic acid Microflora In Colon Drug Release Fig. (1) : Schematics of the conceptual design of CODES TM (Takemura et al., 2000) Microspheres with 2 different Eudragit E 100 : drug : lactulose ratios ( 1 : 1 : 0.5 and ratio 2 = 2 : 1 : 0.5) were prepared. Drug microspheres were prepared by O/W dispersion method using solvent evaporation technique. Prepared microspheres were characterized for average particle sizes and shape using image analyzer. The drug content was determined by an organic solvent extraction procedure. The amount of MB-HCl in the alcoholic solution was determined spectrophotometrically at 264 nm. The interaction between the drug and the polymer was investigated using IR spectrometry. Tableting was performed using Tablet Press under a compression force of 250 kgf/cm 2 using 10 mm (diameter), round and concave punches. Coating was performed by a coating pan technique. First, the tablet cores were coated with acid-soluble coating material, Eudragit® E 100. followed by an enteric coating material Eudragit® L 100 with HPMC barrier in between. The film thickness is expressed in terms of the percentage total weight gain (TWG), and products with a TWG of 3%, 6% and 10% were obtained. In order to find out the in vivo performance of the prepared MB-HCl CODES TM, Tablet containing barium sulphate was ingested to guinea pig. An x- ray image for the GIT was taken every 2 hrs, to visualise the passage of the coated tablet in the GIT of guinea pig and the location at which the tablet begin to disintegrate and release the drug. In order to find out the in vivo performance of the prepared MB-HCl CODES TM, Tablet containing barium sulphate was ingested to guinea pig. An x- ray image for the GIT was taken every 2 hrs, to visualise the passage of the coated tablet in the GIT of guinea pig and the location at which the tablet begin to disintegrate and release the drug. Drug release studies were performed using the rotating basket method according to USP 24 with a rotation speed of 100 rpm. The dissolution of drug was conducted in pH gradient dissolution medium maintained at 37 °C. A tablet was first placed in 0.1 N HCl pH 1.2 for 2 h. (average gastric empting time). Then, the pH was raised to 6.1 for 1 h (average duodenum transit time). The pH was further increased to 7.4 by adding the appropriate amount of trisodium phosphate for 2 h (average intestinal transit time). Finally, the pH was adjusted at 7 and ß-glucosidase was added at a concentration of 0.1% in the last 2 hrs. Aliquots were withdrawn and assayed spectrophotometrically for mebeverine HCl at 264 nm. Uncoated tab Uncoated tab enteric coated tab enteric coated tab enteric coated tab prep from enteric coated tab prep from microspheres (ratio 2:1:0.5) enteric coated tab prep from enteric coated tab prep from microspheres (ratio 1:1:0.5) Fig (4 ): In vitro release of mebeverine HCl from different Fig (4 ): In vitro release of mebeverine HCl from different prepared tablets prepared tablets Figure 4 reveals that, the release of MB-HCl from uncoated tablet was very fast, about 94% of the drug was liberated in one hour. This indicates that, the drug is completely released in the stomach. For (MB-HCl) CODES TM, the tablet didn't disintegrate or release the drug 3 h after immersion into simulated gastric and duodenal conditions (pH 1.2 - 6.1), owing to the protection effect of the enteric coating. In simulated intestinal fluid (pH = 7.4) a slight liberation of the drug was observed {phase 1 (P1)}. At that pH the enteric coat completely dissolve and the drug might leach through the acid-soluble coat (Eudragit E100) which become slightly permeable and swellable (Yang et al 2002). After 2 hours pH was adjusted at 7 and ß-glucosidase was added. From Figure 2 it is to be noticed that, drug was released rapidly from CODES™ after a 5-h lag time to reach 95%, 72% and 60.4% for FI F II and F III, respectively {Phase 2}. This finding is explained by the fact that, the polysaccharide inside the core tablet (lactulose) dissolved and diffused through the coating and degraded by ß-glucosidase into organic acid. This lowered the pH surrounding the system below 5 which is sufficient to dissolve the acid- soluble coat (Yang et al 2002). Subsequently, the drug is target in the colon. The significantly lower drug release percentage of F II and F III compared to F I is due to microencapsulation of the drug in the prepared two formulae (Wu et al., 2003). As expected the higher concentration of the polymer in FIII resulted in a slower drug release as compared with FII, this result was confirmed with the I.R. spectrum study. where, a covalent bond with a double bond of the polymer was formed probably with the drug resulting in the sustained drug release from the microspheres. Figure 2 illustrates that the O/W dispersion method for the preparation of microspheres using solvent evaporation technique as well as the type of solvents used yields microspheres with spherical and uniform shape (Herrmann et al. 1998). Using image analyzer, the figure revealed that, the size of microspheres increases from ≃ 4- 7ųm to 10-12 ųm for microspheres with formula FII and FIII, respectively. IR spectroscopy was done to investigate the interaction between drug and polymer interaction (Fig 3). the principal IR spectral assignments of Mebeverine hydrochloride were observed at the same frequencies (1266, 1715 cm -1 ) for both types of microspheres D, E. However,Observing the functional group region of the IR spectrum of the drug, polymer and microsphere, it is to be noticed that a peak at about 2500 cm -1 in the drug spectrum which is thought to be a (N+-H) formed probably a covalent bond with a double bond of the polymer resulting in a disappearance of that peak in the spectrum of the microsphere. This would explain the sustained drug release from the microspheres. X-ray images of the ingested MB-HCl CODES TM to guinea pig are illustrated in Figure 5. from the figure, the tablet shows no disintegration in the first (2-3 hrs). A result which correlates with the in vitro drug release studies in simulated gastric and duodenal fluids (fig. 5-A). Tracer on the surface of the tablet are present in the small intestine (7-8 hrs), indicating the leaching of few amounts of drug as illustrated in X-ray images (B). This results is in conformation with conducting the in vitro drug release studies in simulated intestinal fluids. The tablets were found to disintegrate almost completely after 10-12 hrs, (fig. 5-C), owing to the effect of enzymatic action of micro flora in the colon which act on lactulose that might leach through the acid-soluble coating layer and produce organic acids with pH sufficient to dissolve the Eudragit E 100 coat. Fig (5a):Intact tablet in the stomach After 2 hrs of ingestion Fig (5b):Intact tablet in the intestine After 6 hrs of ingestion Fig (5c): Intact tablet in the colon After 10 hrs of ingestion Colon-specific drug delivery systems have attracted a great deal of interest recently for the local treatment of colonic disorders. The study provide that CODES TM is one of the very promising techniques which based on a combination of pH and microflora michanisms for the colon targeting of mebeverine hydrochrloride (MB-HCl); an effective spasmolytic drug that acts on gastrointestinal smooth muscle with selective effect on colon. In-vitro release indicates that the drug began to release only at pH 7 and in presence of ß-glucosidase (simulated colonic condition). Furthermore, microspheres containing formulations result in a more sustained effect with prolonged action of MB-HCl in the colon. A condition that is more promising for drugs that are selectively act on colon.