The colon is a site where both local and systemic delivery of drugs can take place. Local delivery allows topical treatment of inflammatory bowel disease. However, treatment can be made effective if the drugs can be targeted directly into the colon, thereby reducing the systemic side effects. This review, mainly compares the primary approaches for CDDS (Colon Specific Drug Delivery) namely prodrugs, pH and time dependent systems, and microbially triggered systems, which achieved limited success and had limitations as compared with newer CDDS namely pressure controlled colonic delivery capsules, CODESTM, and osmotic controlled drug delivery which are unique in terms of achieving in vivo site specificity, and feasibility of manufacturing process.
Abstract. The studies reported in this work are aimed to elucidate the ternary inclusion complex formation of gemfibrozil (GFZ), a poorly water-soluble drug, with β-cyclodextrin (β-CD) with the aid of auxiliary substances like different grades of povidone(s) (viz. PVP K-29/32, PVP K-40, Plasdone S-630, and Polyplasdone XL), organic base (viz. triethanolamine), and metal ion (viz. MgCl 2 ·6H 2 O), by investigating their interactions in solution and solid state. Phase solubility studies were carried out to evaluate the solubilizing power of β-cyclodextrin, in association with various auxiliary substances, to determine the apparent stability constant (K C ) and complexation efficiency (CE) of complexes. Improvement in K C values for ternary complexes clearly proves the benefit of the addition of auxiliary substances to promote CE. Of all the approaches used, the use of polymer Plasdone S-630 was found to be the most promising approach in terms of optimum CE and K C . GFZ-β-CD (1:1) binary and ternary systems were prepared by kneading and lyophilization methods. The ternary systems clearly signified superiority over binary systems in terms of CE, solubility, K C , and reduction in the formulation bulk. Optimized ternary system of GFZ-β-CD-Plasdone S-630 prepared by using lyophilization method indicated a significant improvement in intrinsic dissolution rate when compared with ternary kneaded system. Differential scanning calorimetry, X-ray diffraction, Fourier transform infrared, scanning electron microscopy, and proton nuclear magnetic resonance were carried out to characterize the binary and optimized ternary complex. The results suggested the formation of new solid phases, eliciting strong evidences of ternary inclusion complex formation between GFZ, β-CD, and Plasdone S-630, particularly for lyophilized products.
Drugs for several diseases are still given without regard to the time of the day. Variation in dosing time is generally related with the effectiveness and toxicity of many drugs. On the other hand, several drugs affect the circadian clock. The knowledge of interactions between the circadian clock and drugs is valuable in clinical practice. The pharmacodynamics and pharmacokinetics of the medication influence the chronopharmacological phenomena and recent advances in it have made the traditional goal of pharmaceutics rather outdated. Enhanced progress in chronopharmacotherapy can be achieved if an identification of a rhythmic marker for selecting dosing time is done. However, technology involved in development of drug delivery systems (DDS) that match the circadian rhythm, and the unraveling of the relationship between circardian clock and pathology may be the hindrance in its prosperity for now. The Chronopharmaceutical Drug Delivery System (CDDS) has emerged during the last decade as a possible drug delivery system against several diseases, which may lead to the creation of a sub-disciple of pharmaceutics to be explored called 'chronopharmaceutics'. The review addresses the approaches to this sub-discipline, call attention to potential disease-targets, identifies existing technologies, hurdles and future of chropharmaceuticals. Chronopharmaceuticals coupled with nanotechnology could be the future of DDS, and lead to safer and more efficient disease therapy in the future.
In the present study, an intestinal pH, disintegrating and non-disintegrating dual capsular system using formaldehyde vapor and phase transition technique, respectively, was developed to achieve delayed as well as improved osmotic flow for the model drug cefadroxil. Formaldehyde vapor was used to attain gastric resistance to the outer gelatin capsule, which disintegrated at the intestinal pH to give a non-disintegrating asymmetric membrane capsule (AMC). The AMC was prepared via dry phase inversion process. The effects of different formulation variables were studied based on 2³ factorial design, namely, level of osmogen, ethylcellulose, and pore former, apart from studying the effects of varying osmotic pressure, agitation intensity, and intentional defect on drug release. Scanning electron microscopy showed an outer dense non-porous and an inner lighter porous region for the prepared asymmetric membrane. Statistical test was applied for in-vitro drug release at P > 0.05. The best formulation in the design closely corresponded to the extra design checkpoint formulation by a similarity (f₂) value of 95.28. The drug release was independent of the agitation intensity and intentional defect of the film but dependent on the osmotic pressure of the dissolution medium. The release kinetics followed zero-order, and mechanism of release was Fickian diffusion.
Aim:The aim of the project was to develop cross-linked b-cyclodextrin (CL β-CD) microparticles for controlled delivery of a highly water-soluble drug.Materials and Methods:CL β-CD microparticles were prepared by emulsification phase separation technique using epichlorohydrin as a cross-linking reagent. The developed microparticles were compared with β-CD for their pharmacotechnical properties. A highly water-soluble model drug, pravastatin sodium (PS) was loaded within these hydrophobic microparticles by active drug loading method using nonionic surfactant Tween 80 as the loading facilitator.Results:Maximal drug fixation (216.8 mg/g beads) was observed in pH 4 at 20°C. In vitro release studies of PS-loaded CL β-CD microparticles in simulated gastric fluid and simulated intestinal fluid resulted in modified dissolution profiles. Modeling of release profiles confirmed controlled release (r2 = 0.9910) of PS from the cross-linked system.Conclusion:Controlled release CL β-CD microparticles PS that have the potential to enhance its therapeutic properties by offering the advantage of less frequent dosing and decreased fluctuations in the blood levels during the dosing interval were successfully developed.
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