COLON SPECIFIC DRUG DELIVERY FOR MEBEVERINE COLON SPECIFIC DRUG DELIVERY FOR MEBEVERINE HYDROCHLORIDEHYDROCHLORIDE

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

40004000 35003500 30003000 25002500 20002000 15001500 10001000 500500cmcm-1-1

A

B

Fig ( 2 ): A- (MB-HCl) Microspheres (ratio 1:1:0.5) B- (MB-HCl) Microspheres (ratio 2:1:0.5)

Samia Omar Samia Omar 1 1 , Basmah Al Dossary , Basmah Al Dossary 22, Hanan Refai , Hanan Refai 3 3 , Omaimah Al Gohary, Omaimah Al Gohary 22

1. Department of Pharmaceutics, Faculty of Pharmacy, Helwan University, Cairo, Egypt 1. Department of Pharmaceutics, Faculty of Pharmacy, Helwan University, Cairo, Egypt 22 . .Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, KSADepartment of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, KSA

3. Department of Pharmaceutics, Faculty of Pharmacy, Cairo University, Cairo, Egypt3. Department of Pharmaceutics, Faculty of Pharmacy, Cairo University, Cairo, Egypt

Mebeverine Hydrochloride (MB-HCl) as an effective spasmolytic drug was formulated as a CODESMebeverine Hydrochloride (MB-HCl) as an effective spasmolytic drug was formulated as a CODESTMTM . The core tablet containing . The core tablet containing lactulose and the drug lactulose and the drug in free form in free form {formula 1 (F{formula 1 (F11)})},, or or as microspheres with 2 different polymer :drug :lactulose ratios (1:1:0.5 and 2:1:0.5) as microspheres with 2 different polymer :drug :lactulose ratios (1:1:0.5 and 2:1:0.5)

{formula 2 (F{formula 2 (F22) and formula (F) and formula (F33)} respectively)} respectively.. The core was coated by Eudragit The core was coated by Eudragit E E100100 which was then coated by Eudragit which was then coated by Eudragit L L100100. The release . The release

profiles of the coated CODESprofiles of the coated CODESTMTM systems were compared with uncoated compressed tablets. The uncoated tablet showed a drug release of 93% 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 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 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 (Pfluid (pH 7.4) {phase 1 (P11)}. After 4)}. After 4 hours pH was adjusted at 7 and hours pH was adjusted at 7 and ß-ß-glucose-oxidase was added, which is an enzyme produced by glucose-oxidase was added, which is an enzyme produced by

enterobacteriaenterobacteria present in the colon present in the colon.. The drug release suddenly increased to reach 95%, 72% and 60.4% for F The drug release suddenly increased to reach 95%, 72% and 60.4% for F11, F, F22 and F and F33, respectively. This result , respectively. This result

was confirmed with the I.R. 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 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 (presulting in the sustained drug release from the microspheres with a significant difference (p>> 0.01) for 0.01) for MB-HCl released from CODESMB-HCl released from CODESTMTM and and CODESCODESTMTM prepared from microspheres. prepared from microspheres. This colon-specific drug delivery technology was confirmed by the in This colon-specific drug delivery technology was confirmed by the in vivovivo investigation investigation, using X-ray , using X-ray

images for images for guinea pigsguinea pigs, where the tablet began to disintegrate after 10 hrs of tablet swollen. , where the tablet began to disintegrate after 10 hrs of tablet swollen. The results of our study show that The results of our study show that Mebeverine Mebeverine Hydrochloride CODESHydrochloride CODESTMTM colon-specific drug delivery can act as a colon-specific drug delivery can act as a successfulsuccessful trigger for drug release in the colon from specially coated tablets trigger for drug release in the colon from specially coated tablets

containing containing microspheresmicrospheres..

Enteric Coating Enteric Coating Eudragit L 100Eudragit L 100In StomachIn StomachHPMC CoatingHPMC Coating

Acid-soluble CoatingAcid-soluble Coating(Eudragit E100)(Eudragit E100)

In Small In Small IntestineIntestine

LactuloseLactulose

Organic acidOrganic acidMicrofloraMicrofloraIn ColonIn Colon

Drug ReleaseDrug Release

Fig. (1) : Schematics of the conceptual design of CODESFig. (1) : Schematics of the conceptual design of CODESTMTM (Takemura et al., 2000)(Takemura et al., 2000)

Microspheres with 2 different Eudragit EMicrospheres with 2 different Eudragit E100100 : drug : lactulose ratios ( 1 : 1 : 0.5 : drug : lactulose ratios ( 1 : 1 : 0.5

and ratio 2 = 2 : 1 : 0.5) were prepared. Drug microspheres were prepared by and ratio 2 = 2 : 1 : 0.5) were prepared. Drug microspheres were prepared by O/W dispersion method using solvent evaporation technique. O/W dispersion method using solvent evaporation technique.

Prepared microspheres were characterized for average particle sizes and shape Prepared microspheres were characterized for average particle sizes and shape using image analyzer. using image analyzer.

The drug content was determined by an organic solvent extraction procedure. The drug content was determined by an organic solvent extraction procedure. The amount of MB-HCl in the alcoholic solution was determined The amount of MB-HCl in the alcoholic solution was determined

spectrophotometrically at 264 nm. spectrophotometrically at 264 nm. The interaction between the drug and the polymer was investigated using IR The interaction between the drug and the polymer was investigated using IR

spectrometry.spectrometry.

Tableting was performed using Tablet Press under a compression force of 250 Tableting was performed using Tablet Press under a compression force of 250 kgf/cmkgf/cm22 using 10 mm (diameter), round and concave punches. using 10 mm (diameter), round and concave punches.

Coating was performed by a coating pan technique. First, the tablet cores were Coating was performed by a coating pan technique. First, the tablet cores were coated with acid-soluble coating material, Eudragit® Ecoated with acid-soluble coating material, Eudragit® E100100. followed by an enteric . followed by an enteric

coating material Eudragit® Lcoating material Eudragit® L100100 with HPMC barrier in between.with HPMC barrier in between. The film The film

thickness is expressed in terms of the percentage total weight gain (TWG), and thickness is expressed in terms of the percentage total weight gain (TWG), and products with a TWG of 3%, 6% and 10% were obtained.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 In order to find out the in vivo performance of the prepared MB-HCl CODESCODESTMTM, Tablet containing barium sulphate was ingested to guinea pig. An x-, 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 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 coated tablet in the GIT of guinea pig and the location at which the tablet begin

to disintegrate and release the drug.to disintegrate and release the drug.

Drug release studies were performed using the rotating basket method according 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 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 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, 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 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 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 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. 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 Aliquots were withdrawn and assayed spectrophotometrically for mebeverine HCl at 264 nm.HCl at 264 nm.

0

2040

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80100

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0 100 200 300 400 500Time (min)

% D

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ease

d

Uncoated tabUncoated tab enteric coated tabenteric coated tab

enteric coated tab prep fromenteric coated tab prep frommicrospheres (ratio 2:1:0.5)microspheres (ratio 2:1:0.5)

enteric coated tab prep fromenteric coated tab prep frommicrospheres (ratio 1:1:0.5)microspheres (ratio 1:1:0.5)

Fig (4 ): In vitro release of mebeverine HCl from differentFig (4 ): In vitro release of mebeverine HCl from different prepared tabletsprepared tablets

FigFigure ure 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 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) CODESdrug is completely released in the stomach. For (MB-HCl) CODESTMTM , , the tablet didn't disintegrate or release the drug 3 h after immersion intothe tablet didn't disintegrate or release the drug 3 h after immersion into simulated 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 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 liberation of the drug was observed {phase 1 (P1)}. At that pH the enteric coat completely dissolve and the drug might leach throughmight leach through the acid-soluble coat the acid-soluble coat (Eudragit E100) which become slightly permeable and swellable (Eudragit E100) which become slightly permeable and swellable (Yang et al 2002).(Yang et al 2002). After 2 hours pH was adjusted at 7 and After 2 hours pH was adjusted at 7 and ß-ß-glucosidase was added. From glucosidase was added. From Figure 2 it is to be noticed that, drug Figure 2 it is to be noticed that, drug was released rapidly from CODES™was released rapidly from CODES™ after a 5-h lag time after a 5-h lag time to reach 95%, 72% and 60.4% for FI F II and F III, 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 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 coating and degraded by ß-ß-glucosidase into organic acid. This lowered the pH surrounding the system below 5 which is sufficient to dissolve the acid-glucosidase into organic acid. This lowered the pH surrounding the system below 5 which is sufficient to dissolve the acid-soluble coat soluble coat (Yang et al 2002).(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 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 F I is due to microencapsulation of the drug in the prepared two formulae (Wu et al., 2003).(Wu et al., 2003). As expected the higher concentration of the polymer in FIII 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. 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 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. of the polymer was formed probably with the drug resulting in the sustained drug release from the microspheres.

Figure 2 illustrates that the Figure 2 illustrates that the O/W dispersion method for O/W dispersion method for the the preparation of microspheres preparation of microspheres using solvent using solvent evaporation technique as well as the type of solvents used evaporation technique as well as the type of solvents used yields yields microspheres with spherical and uniform shape microspheres with spherical and uniform shape (Herrmann et al. 1998)(Herrmann et al. 1998).. Using image analyzer, the figure Using image analyzer, the figure revealed that, the size of microspheres increases from ≃revealed that, the size of microspheres increases from ≃4-74-7ųm to 10-12 ųm to 10-12 ųm for microspheres with formula FII ųm for microspheres with formula FII and FIII, respectively.and FIII, respectively.

IR spectroscopy was done to investigate the interaction between drug and IR spectroscopy was done to investigate the interaction between drug and polymer interaction (Fig 3). the principal IR spectral assignments of polymer interaction (Fig 3). the principal IR spectral assignments of Mebeverine hydrochloride were observed at the same frequencies (1266, 1715 Mebeverine hydrochloride were observed at the same frequencies (1266, 1715 cmcm-1-1) for both types of microspheres D, E. However,Observing the functional ) 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 group region of the IR spectrum of the drug, polymer and microsphere, it is to be noticed that a peak at about 2500 cmbe noticed that a peak at about 2500 cm -1-1 in the drug spectrum which is in the drug spectrum which is thought to be a (N+-H) formed probably a covalent bond with a double bond 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 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 microsphere. This would explain the sustained drug release from the microspheres.microspheres.

X-ray images of the ingested X-ray images of the ingested MB-HCl CODESMB-HCl CODESTMTM to guinea pig are to guinea pig are illustrated in illustrated in Figure 5. from the figure, the tablet shows no disintegration 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 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 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 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 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 results is in conformation with conducting the in vitro drug release studies in simulated intestinal fluids. The tablets were found to disintegrate almost 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 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 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 the acid-soluble coating layer and produce organic acids with pH sufficient to dissolve the Eudragit Eto dissolve the Eudragit E100100 coat. coat.

Fig (5a):Intact tablet in the stomachFig (5a):Intact tablet in the stomachAfter 2 hrs of ingestionAfter 2 hrs of ingestion

Fig (5b):Intact tablet in the intestineFig (5b):Intact tablet in the intestine After 6 hrs of ingestionAfter 6 hrs of ingestion

Fig (5c): Intact tablet in the colonFig (5c): Intact tablet in the colon After 10 hrs of ingestionAfter 10 hrs of ingestion

Colon-specific drug delivery systems have attracted a great deal of Colon-specific drug delivery systems have attracted a great deal of interest recently for the local treatment of colonic disorders. The study interest recently for the local treatment of colonic disorders. The study provide that CODESprovide that CODESTM TM is one of the very promising techniques which is one of the very promising techniques which based on based on a a combination of pH and microfloracombination of pH and microflora michanisms michanisms for the for the colon targeting of mebeverine hydrochrloride (MB-HCl); an effective colon targeting of mebeverine hydrochrloride (MB-HCl); an effective spasmolytic drug that acts on gastrointestinal smooth muscle with spasmolytic drug that acts on gastrointestinal smooth muscle with selective effect on colon. In-vitro release indicates that the drug began selective effect on colon. In-vitro release indicates that the drug began to release only at pH 7 and in presence of to release only at pH 7 and in presence of ß-ß-glucosidase (simulated glucosidase (simulated colonic condition). Furthermore, microspheres containing formulations colonic condition). Furthermore, microspheres containing formulations result in a more sustained effect with prolonged action of MB-HCl in result in a more sustained effect with prolonged action of MB-HCl in the colon. A condition that is more the colon. A condition that is more promising for drugs that are promising for drugs that are selectively act on colon. selectively act on colon.