colon specific drug delivery

A novel polymer based on azobenzene-4,4’-diacetic allyl ester as core linker polycondensated with methyl methacrylate and n-butyl methacrylate was conveniently synthesized for the purpose of targeting colonic drug delivery. The cross linker was characterized by infrared spectroscopy, nuclear magnetic resonance and mass spectroscopy. The synthesized polymers (PMB) showed good film forming. Comparative study of synthesized polymers was done using In-vitro drug release pattern of budesonide from polymer coated capsule formulation in colonic media. Budesonide capsules coated with PMB1:1:2: B and PMB1:1:3: B showed maximum drug release in colon in a sustained release manner.

  Targeted drug delivery to the colon is more desirable for local treatment of a variety of bowel diseases and systemic delivery of protein and peptide drugs. Targeting depends on exploiting a unique feature of specific site and protecting the drug until it reaches to the site. To achieve the delivery of intact drugs to the colon, different primary as well as potential novel approaches are used. To achieve the maximum site specific delivery of drugs to colon, combination of two or more approaches are preferred over individual approaches. Because of limited success of primary approaches newly developed approaches are preferred.

In the present investigation, pH-dependent and controlled drug release polymeric microspheres of Ornidazole were developed to deliver the active molecule to the colonic region. Microspheres were prepared by emulsion cross-linking method with some modifications, using different proportions of Ornidazole and Polymers (guar gum and gelatin). Gelatin microspheres were coated with Acrycoat L100 to achieve pH sensitive properties and specific biodegradability for colon targeted delivery of Ornidazole. Microspheres were evaluated for size, morphology, sphericity study, % yield, loose surface crystal study, drug content and entrapment efficiency. In vitro drug release study was conducted by buffer change method to mimic GIT environment using buffer solutions of varying pH. The investigations revealed that microspheres prepared with Ornidazole: guar gum ratio (1:2) shows only 10.003±0.885 % drug was released in first 5 hours and 38.849 ± 0.62 % in 12 hours, which proves the potentiality of guar gum for colonic delivery of drugs. While for microspheres prepared with Ornidazole: gelatin (1:2) and coated with Arycoat L100 shows 16.596 ± 3.18 % drug release in first 5 hours and 45.921 ± 3.07 % in 12 hours. Key Words: colon specific drug delivery, biodegradable polymers, pH-dependent release, In vitro drug release