Targeting Pharmaceutical Drugs to the Colon Makes It Possible to Achieve Local Or Systemic

• Targeting pharmaceutical drugs to the colon makes it possible to achieve local or systemic drug delivery to this site. To deliver the compounds in a non-degraded form to the lower part of the gastrointestinal tract, they must use the characteristics of the colon to specifically release the drugs in this part of the digestive tract.
• Among the different approaches available to achieve targeted drug release to the colon, the use of especially pH sensitive microspheres holds great promise.
• Microspheres received much attention not only for prolonged release but also for targeting of the drugs to the site.
• Microspheres have the potential to increase the availability of drug levels at the site and act as a depot for the extended release of drug.

• Varshosaz J et al. synthesized chitosan microspheres for Mesalazine release and found greatest release in presence of ceacal secretions1.
• Lamprecht A et al. designed microspheres for colonic delivery of Tacrolimus and found oil/water technique superior for maximum release2.
• Mahaveer D et al. synthesized Poly (vinyl alcohol) and poly (acrylic acid) interpenetrating network microspheres for the delivery of Diclofenac sodium to the intestine and found maximum release in the intestine3.
• Brahma N singh et al. characterized physicochemical interactions of a multiparticulate formulation for colonic delivery of Azathioprine and found product stability and efficacy for treatment of inflammatory bowel disease4.
• Carelli V et al. synthesized polyoxyethylene-poly(methacrylic acid-co-methyl methacrylate) compounds for site-specific peroral delivery of Prednisolone and observed specific extended delivery of drug to colon than ileum5.

• Sakagami M et al. synthesized Beclomethasone dipropionate microspheres for powder inhalation. It was observed that prolonged lung retention of drug by HPC microspheres was attributed to prolonging its pharmacological duration without requiring increased drug dosage6.
• Fwu-Long Mi et al. synthesized Iron-carboxymethyl chitin microspheres for pH-sensitive release of 6-Mercaptopurine and found decreased drug release with increased concentration of ferric chloride solution7.
• Lorenzo M.L et al. designed microencapsulated chitosan microspheres for colonic drug delivery and presented new approach for the modification of chitosan as well as new system with a great potential for colonic drug delivery8.
• Krishna Rao K.S.V et al. developed novel chitosan based pH-sensitive interpenetrating network for the controlled releaseof Cefadroxil and their studies were able to extend the release rates from conventional dosage release time to more than 10hrs9.
• Rokhade A.P et al. synthesized and characterised semi-interpenetrating polymer network microspheres of acrylamide grafted on dextran and chitosan for controlled release of Acyclovir and observed the dependence of drug release rates on both the extent of crosslinking and amount of acrylamide grafted on dextran used in preparing microspheres10.

1. To formulate microspheres consisting of an ulcerative colitis drug.
2. To estimate the drug concentration entrapped in the prepared microspheres.
3. To evaluate the prepared microspheres.
4. To characterize the prepared microspheres by DSC and SEM.
5. To carry out the stability studies of the optimized formulations.

List of References:

1. Varshosaz J, Jaffarian Dehkordi A, Golafshan S. Colon-specific delivery of mesalazine chitosan microspheres. J of Microencapsulation 23; 2006; 329-339.
2. Lamprecht A, Yamamoto H, Takeuchi H, Kawashima Y. Design of pH-sensitive microspheres for the colonic delivery of the immunosuppressive drug tacrolimus. Eur J of Pharm and Biopharm 58; 2004; 37-43.

1. Mahaveer D Kurkuri and Tejaraj M Aminabhavi. Poly(vinyl alcohol) and poly(acrylic acid) sequential interpenetrating network pH-sensitive microspheres for the delivery of diclofenac sodium to the intestine. J of Controlled Release 96; 2004; 9-20.
2. Brahma N. Singh and Kwon H. Kim. Characterization and relevance of physicochemical interactions among components of a novel multiparticulate formulation for colonic delivery of azathioprine. Int J Pharm 341; 2007; 143-151.
3. Carelli V, Di Colo G, Nanniperi E, Poli B and Serafini M.F. Polyxyethylene-poly(methacrylic acid-co-methyl methacrylate) compounds for site-specific peroral delivery of prednisolone. Int J Pharm 202; 2000; 103-112.
4. Masahiro sakagami, Wataru Kinoshita, Kiyoyuki Sakon, Jun-ichi Sato and Yuji Makino. Mucoadhesive beclomethasone microspheres for powder inhalation: their pharmacokinetics and pharmacodynamics evaluation. J of Controlled Release 80; 2002; 207-218.
5. Fwu-Long Mi, Chin-Ta Chen, Yuan-Cheng Tseng, Chih-Yang Kuan and Shin-Shing Shyu. Iron-carboxymethylchitin microspheres for the pH-sensitve release of 6-mercaptopurine. J of Controlled Release 44; 1997; 19-32.
6. Lorenzo M.L, Lopez C.R, .Jato J.L.V and Alonso M.J. Design of microencapsulated chitosan microspheres for colonic drug delivery. J of Controlled Release 52; 1998; 109-118.
7. Krishna Rao K.S.V, Naidu B.V.K, Subha M.C.S, Sairam M and Aminabhavi T.M. Novel chitosan-based pH-sensitive interpenetrating network microgels for the controlled release of cefadroxil. Carbohydrate polymers 66; 2006; 333-344.
8. Rokhade A.P, Sangamesh A Patil and Tejraj M Aminabhavi. Synthesis and characterization of semi-interpenetrating polymer network microspheres of acrylamide grafted dextran and chitosan for controlled releaseof acyclovir. Carbohydrate polymers67; 2007; 605-613.