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Pharmacoscintigraphy is a non-invasive technique for determining the fate of drugs after administration into humans. Collecting valuable information through the pharmacoscintigraphyabout absorption and release mechanisms of drugs from formulations, and thus proving to be an invaluable tool in developing newer and more effective formulations. Such studies can be used to determine the behavior of drugs, formulation as well as diagnostic agents that are administered. In this technique, radiolabelled formulations are administered to patients by their intended route of administration. Their transit through the body is monitored using sophisticated imaging cameras. Since the amount of radiotracer that is used is very low, this is a safe, efficient, and accurate method for studying the behavior of drugs in the human body. Preclinical studies of newer drugs have successfully been carried out using the pharmacoscintigraphic technique
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AIM To prepare colon-targeted pellets of Prunellae Spica effective components and to evaluate the in vitro drug-release behaviors.METHODS Fluidized bed coating method was adopted in the preparation of pellets.With in vitro accumulative release rate as an evaluation index,hydroxypropyl methyl cellulose (HMPC),polyacrylic resin (Eudragit S100) and triethyl citrate (TEC) amounts as influencing factors,orthogonal test was applied to optimizing the formulation.The in vitro drug-release behaviors were evaluated with rosmarinic acid content as an index.RESULTS The optimal formulation was determined to be 5％ for HPMC amount,70％ for Eudragit S100 amount,and 20％ for TEC amount.The obtained pellets attained an accumulative release rate of more than 90％ in pH 7.6 PBS (transportation for 2 h),while no drug dissolution was found in pH 1.0 HCl (transportation for 2 h) or pH 6.8 PBS (transportation for 3 h).CONCLUSION Colon-targeted pellets of Prunellae Spica effective components can achieve in vitro colon-targeted effect.
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Objective: To prepare the pH dependent-microbially triggered colon targeted pellets of Rheum and optimize the preparation formulation of the targeted pellets. Methods: The pill-core was prepared by dropping preparation method, the pill-core fomulation was optimized by the orthogonal test, with drug loading, entrapment rate, and releasing rate as indexes. With release performance as index, the lagging cover weight increment was screened, the Rheum pellet that released at colon was obtained. Results: The 2% alginate-pectin solution, 0.7% chitosan solution, 1% CaCl2 solution, chitosan-CaCl2 solution with pH of 6.0, and the 4∶1 quantity of reagent (Rheum-accessory) were chosen as the top gallant fomulation to prepare the pill core, then enteric coating weight increased to 30% and the enteric coated-pellet was obtained. In gastric juice after 2 h and in small intestinal juice after 3 h, the coated pellet is cumulatively released to 2.01% and 8.72%, respectively, and released to 92.58% in the colon fluid after 4 h. Conclusion: The preparation fomulation of colon targeted pellet of Rheum is definited, and the colon targeted release is preliminary implemented.
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Objective: To prepare pH-dependent Paridis Rhizoma saponin (PRS) and Astragali Radix polysaccharide (ARP) colon targeting pellets for the treatment of colon cancer and finish its in vitro release performance evaluation. Methods: The colon targeted pellets were prepared with extrusion-spheronization and air-flow coating method and the the process parameters were optimized by orthogonal design. The coating fluid prescription was investigated by single factor test. In vitro release performance evaluation of the pellets was evaluated with polyphyllin I and II as the indexes. Results: The optimum technologic parameters of extrusion spheronization equipment were as follows: the rate of extrusion was 60 r/min, the rate of spheronization was 1 200 r/min, and the time of spheronization was 5 min. The optimum coating liquid formulation of pH-dependent colon targetting pellets was 15% weight gains of Eudrugit S100, 1.5% anti-plastering aid amount of Glycerin monostearate, and 5% plasticizer amount of TEC. In vitro release test showed that cumulative release rate of berberine hydrochloride was close to 0% in artificial gastric juice after 2 h and less than 10% in artificial intestinal fluid after 4 h, but the cumulative release rate in artificial colon juice after 2 h was more than 90%. Conclusion: The preparation method can be applied to the preparation of colon targeted pellets and the pellets can achieve the targeted release in the colon.
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ABSTRACT The objective of this research was to design a new colon-targeted drug delivery system based on chitosan. The properties of the films were studied to obtain useful information about the possible applications of composite films. The composite films were used in a bilayer system to investigate their feasibility as coating materials. Tensile strength, swelling degree, solubility, biodegradation degree, Fourier transform infrared spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Scanning electron microscope (SEM) investigations showed that the composite film was formed when chitosan and gelatin were jointly reacted jointly. The results showed that a 6:4 blend ratio was the optimal chitosan/gelatin blend ratio. In vitro drug release results indicated that the Eudragit- and chitosan/gelatin-bilayer coating system prevented drug release in simulated intestinal fluid (SIF) and simulated gastric fluid (SGF). However, the drug release from a bilayer-coated tablet in SCF increased over time, and the drug was almost completely released after 24 h. Overall, colon-targeted drug delivery was achieved by using a chitosan/gelatin complex film and a multilayer coating system.
RESUMO O objetivo desta pesquisa foi planejar um novo sistema de liberação de fármacos direcionado ao cólon, utilizando quitosana. Estudaram-se as propriedades dos filmes a fim de obter informações úteis sobre a aplicação desses filmes compósitos. Utilizaram-se os filmes compósitos em sistema de bicamada para investigar a sua viabilidade como materiais de revestimento. Estudos de resistência à tração, grau de intumescimento, solubilidade, grau de biodegradação, no infravermelho por transformada de Fourier (FTIR), de calorimetria diferencial de varredura (DSC) e de microscopia eletrônica de varredura (SEM) mostraram que o filme compósito se formou quando a quitosana e a gelatina reagiram entre si. Os resultados mostraram que a mistura de proporção ótima foi de 6:4 de quitosana:gelatina. Resultados da liberação do fármaco in vitro indicaram que o sistema de revestimento de Eudragit e bicamada de quitosana/gelatina impediu a liberação de fármaco em fluido intestinal simulado (SIF) e em fluido gástrico simulado (SGF). Entretanto, a liberação de fármaco do comprimido revestido em bicamada no SCF aumentou ao longo do tempo e o fármaco foi quase completamente liberado após 24 h. Em geral, se obteve a forma de liberação dirigida ao cólon, utilizando filme complexo de quitosana/gelatina e sistema de revestimento multicamada.
Subject(s)
Hydrocortisone/pharmacokinetics , Colon/drug effects , Tablets/pharmacokinetics , Calorimetry, Differential Scanning/methods , Microscopy, Electron, Scanning/methods , Spectroscopy, Fourier Transform Infrared/methods , Chitosan/pharmacokineticsABSTRACT
By researching the relevant papers at home and abroad, the principles of preparation, drug release mechanism, existing problems and so on were analysed and summarized on prodrugs triggered by colon bacteria-releasing enzymes (PTCBE). Compared with ordinary drugs, PTCBE was degraded by colon bacteria-releasing enzymes on colon-targeted treatment. PTCBE have the drug release characters of specificity, accuracy and so on for the colon-targeted treatment and can reduce the adverse drug reactions. Thus PTCBE have the good prospects of applications.
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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.
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The aim of the present work was to develop and evaluate colon specific sustained release tablet using levetiracetam (LEV), microbially degradable polymeric carrier (pectin), coating material and matrix forming polymers. The colon targeted tablet was prepared by wet granulation technique using different percentage of pectin as matrix carrier, starch mucilage as a binding agent, HPMC K-100 as swellable polymer and coated with Eudragit polymers. Pectin, drug and physical mixture were evaluated for incompatibility study by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). All the batches of matrix tablet (F1-F4) were subjected for in-vitro dissolution in various simulated gastric fluids for suitability for colon specific drug delivery system. Tablets were evaluated for micromeritic properties of granules, physical properties, drug content, water uptake and erosion characteristics. F2 was optimized and subjected to coating based on evaluation results. The dissolution study of F2 revealed, in simulated intestinal fluid (SIF) release was 40.48% at the end of 6h and in simulated colonic fluids (rat caecal content) was 102.88% after degradation at the end of 8h. The colon targeted matrix tablet of LEV showed no change either in physical appearance, drug content or dissolution pattern after performing stability study for 3 months. The studies confirmed that, the designed formulation could be used potentially for colon delivery by controlling drug release in stomach and the small intestine.
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Sodium carboxymethyl cellulose is an excellent pharmaceutical excipient. It possesses good filmability, mucoadhesiv-ity, viscolising capacity and bindability. The current aim of our research work is to synthesize a novel colon targeting polymer by using sodium carboxymethyl cellulose and glycine for colon targeting and to screen its colon specificity by in-vitro release model. Sodium carboxymethyl cellulose was subjected for synthesizing its derivative with glycine using azo linkage. The azo polymeric conjugate was evaluated for its color, solubility, Rf value, melting point, IR and 1HNMR spectral analysis. It was further subjected for evaluating its colon targeting property by in-vitro method using rat fecal matter. The research study revealed that the sodium carboxymethyl cellulose azo derivative showed promising colon specificity for a period of 120 minutes in a controlled manner along with modified solubility. So it can serve as a potential colon targeting polymer.
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Sodium carboxymethyl cellulose is an excellent pharmaceutical excipient. It possesses good filmability, mucoadhesiv-ity, viscolising capacity and bindability. The current aim of our research work is to synthesize a novel colon targeting polymer by using sodium carboxymethyl cellulose and glycine for colon targeting and to screen its colon specificity by in-vitro release model. Sodium carboxymethyl cellulose was subjected for synthesizing its derivative with glycine using azo linkage. The azo polymeric conjugate was evaluated for its color, solubility, Rf value, melting point, IR and 1HNMR spectral analysis. It was further subjected for evaluating its colon targeting property by in-vitro method using rat fecal matter. The research study revealed that the sodium carboxymethyl cellulose azo derivative showed promising colon specificity for a period of 120 minutes in a controlled manner along with modified solubility. So it can serve as a potential colon targeting polymer.
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AIM: To explore the transport and delivery of active drug from dexamethasone-angelica sinensis polysaccharides prodrug in the gastrointestinal tract of rats. METHODS: Dexamethasone and the prodrug were orally administered to rats at the dose of 1.96 mg?kg~ -1 (calculated by carried dexamethasone). The drugs in the plasma and contents of different parts of the rats' gastrointestinal tract were determined by high performance liquid chromatography (HPLC). RESULTS: Dexamethasone carried by the prodrug was mainly released in the contents and mucosa of cecum and colon after oral administration of the prodrug. The absorption of released dexamethasone was reduced significantly. The peak time, peak concentration and AUC were 7.2 h , 42 ?g?L~ -1 and 334 ?g?h?L~ -1 , respectively. However, free dexamethasone was found mainly in the contents and mucosa of the stomach, proximal and distal small intestine after oral administration. The peak time, peak concentration and AUC were 2.2 h, 2 120 ?g?L~ -1 and 11 875 ?g?h?L~ -1 , respectively. CONCLUSION: Dexamethasone can be specifically delivered to the cecum and colon by using dexamethasone- angelica sinensis polysaccharides prodrug. The absorption of dexamethasone was reduced significantly and the drug concentration in colon was increased significantly. The prodrug has a potential in the treatment of colitis.
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Objective:To investigate the in vivo behavior of colon-targeted thymosin ?1 (T?1) tablets. Methods: Colon-targeted T?1 tablets were labelled with ~(99m)Tc and were given to 6 healthy male volunteers orally. Gamma-scintigraphy was used to monitor the gastrointestinal transit and release site of the labelled drug. Results: The labelled drug became detectable in the colon 6.5 h after administration in 5 volunteers with normal intestinal peristalsis and 4.5 h after administration in 1 with sthenic intestinal peristalsis. The images caused by drug release became notable in the colon with the prolongation of releasing time. Conclusion: T?1 tablets is colon-targeted during drug delivery in human gastrointestinal tract.
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Objective:To determine the in vitro release of two kinds of Changankang Pellets (Radix Astragall, Rhizama coptid) coated with Surelease and Eudragit respectively and verify their colon-targeted release in vivo through X-ray photography. Methods: Changankang Pellets were made by mixing the medical BaSO 4 powder and appropriate drugs together according to original produce and coat methods. After determining their in vitro release, they were tested in vivo by 2 volunteers. X-ray films were taken after appropriate time and analyzed to determine the location and status of these pellets inside healthy objects. Results: Pellets made by this way can carry drugs through stomach, intestine and targeted-release them in colon; the coating combined with pH-dependent and time-dependent Eudragit thin layer has better results. Conclusion: X-ray radiography applying BaSO 4 powder could be taken as a quality control method for colon-targeted release drugs. The preliminary results showed that Changankang Pellets met the requirements of colon-targeted release.