The review provides an overview of the approaches, applications, and methods for ester prodrugs. Ester prodrugs are pharmacologically inactive compounds in their original form but become active drugs on biotransformat...The review provides an overview of the approaches, applications, and methods for ester prodrugs. Ester prodrugs are pharmacologically inactive compounds in their original form but become active drugs on biotransformation within the body, which offers advantages concerning the solubility, stability, and targeted delivery of the active drug. Several approaches of ester prodrugs have been reviewed in this review, including simple ester prodrugs, amino acid ester prodrugs, sugar ester prodrugs, lipid ester prodrugs, and polymeric ester prodrugs. This review incorporates in vitro and in vivo methods as well as the characterization of physical and chemical properties for ester prodrugs, cell culture systems, enzymatic assays, and animal models—all of these having a very important bearing on the evaluation of stability, bioavailability, and efficacy for ester prodrugs. While the benefits of using ester prodrugs are significant, there are also disadvantages like instability, poor or variable enzymatic hydrolysis, and toxicity from released promoieties or by-products. This review discusses solutions to the various limitations that include enhancing stability with ionizable promoieties and using physiologically-based pharmacokinetic modeling. The review also highlights the application of ester prodrugs in neurological disorders, such as Parkinson’s disease, and the ongoing efforts to address the critical limitations in treatment efficacy. Future prodrug strategies are poised to advance significantly by harnessing diverse transport mechanisms across the blood-brain barrier and integrating nanotechnology.展开更多
Some Triptorelin<sup>®</sup> (TRP) conjugates of triphenylmethanol derivatives (TPMs) with optimized hydrophobicity were synthesized by reacting 2-substituted methoxy benzenes with 1,3,5-trioxane, fol...Some Triptorelin<sup>®</sup> (TRP) conjugates of triphenylmethanol derivatives (TPMs) with optimized hydrophobicity were synthesized by reacting 2-substituted methoxy benzenes with 1,3,5-trioxane, followed by the conjugation with TRP and sebacic acid to produce TRP-TPMs derivatives. Comparative antiproliferative assays between TRP-TPMs conjugates and the corresponding non-covalent physical mixtures of the TPMs derivatives and TRP were used to treat human acute lymphoblastic leukemia (CCRF-CEM), human ovarian adenocarcinoma (SK-OV-3) and mouse preadipocytes (3T3-L1) cells. TRP-TPMs conjugates at the 50 μM inhibited cell proliferation in CCRF-CEM, SK-OV-3 and 3T3-L1 cells by 21% - 37%, 24% - 73%, 37% - 56%, respectively following incubation for 72 h. These findings indicate that TRP-TPMs derivatives have the potential to enhance the biological activity of TRP.展开更多
Epidemiological studies indicate that treatment with metformin, an AMP-activated protein kinase (AMPK) activator, reduces the incidence of cancers. Activation of AMPK has also been reported to oppose tumor progression...Epidemiological studies indicate that treatment with metformin, an AMP-activated protein kinase (AMPK) activator, reduces the incidence of cancers. Activation of AMPK has also been reported to oppose tumor progression in diverse types of cancers and offers promising cancer therapy. Furthermore, AMPK is a primary regulator of energy metabolism and has also been implicated in cell cycle progression, angiogenesis, cell transformation, migration, and cancer. We have recently synthesized novel flavonoids, namely, triphenylmethanol derivatives (TPMs), but the effectiveness of the TPMs on the activity of AMPK remains unclear. We hypothesized that the novel TPMs would inhibit cancer cell proliferation through the activation of AMPK isoforms in cells. The effects of TPMs on prostate cells (PC-3) were investigated. Cells were exposed to TPMs for either 12 or 24 hr. at the respective doses of 0, 25, 50 100, and 200 µM based on the cell viability studies by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a tetrazole) (MTT) assay. The results indicate that cells exposed to the respective doses of TPMs increased both phospho- and total-AMPKα1 in a dose- and time-dependent manner. The effects of the increases for the phospho- and total-AMPKα in cells were greater for the 24-hr than the 12-hr. incubation. Further studies are currently going on to elucidate the specificities of the said insults in increasing the phospho- and total-AMPKα activities and for the other respective isoforms.展开更多
Cancer enzymology is a promising filiation of bio-medical sciences. In thepast decades, enzymes, such as GST(glutathione S-transferase) , PKC(protein kinase C) , Topo(DNAtopoisomerases), TK(tyrosine kinase), CD (bacte...Cancer enzymology is a promising filiation of bio-medical sciences. In thepast decades, enzymes, such as GST(glutathione S-transferase) , PKC(protein kinase C) , Topo(DNAtopoisomerases), TK(tyrosine kinase), CD (bacterial cytosine deaminase), CPG2(carboxypeptidase G2) ,and PNP (purine nucleoside phosphorylase), have been known to bear close relations to cancer. Theirspecific expression and influence on the process of tumor initiation, promotion and progressionattract scientists to apply them as a biochemical marker of certain malignant tumor, a predictor ofresponse in cancer chemotherapy; to apply them to drug design, tumor prevention and as adjuvant toradiotherapy or surgery.展开更多
Peramivir was a novel and highly potent neuraminidase(NA) inhibitor for the treatment of influenza A and B. However, it exhibited a very low oral bioavailability(only 3%) due to the high polarity(log P of-1.4) and the...Peramivir was a novel and highly potent neuraminidase(NA) inhibitor for the treatment of influenza A and B. However, it exhibited a very low oral bioavailability(only 3%) due to the high polarity(log P of-1.4) and the low membrane permeability across the intestine. To utilize the PEPT1-mediated prodrug strategy to improve the oral absorption and develop the oral alternative, seven amino acid ester prodrugs and seven amino acid amide prodrugs have been synthesized. The permeability of these prodrugs across Caco-2 cells were screened. Peramivr-(CH_2)_2-l-Val and Peramivir-l-Ile were of the highest permeability in ester prodrugs and amide prodrugs, respectively, and then they were selected for further studies. Glycylsarcosine(gly-sar) uptake by Caco-2 could be inbihited by Peramivir-(CH_2)_2-l-Val and Peramivir-l-Ile in a concentration-dependent manner, and the IC 50 was 1.34 ± 0.31 m M and 1.78 ± 0.48 m M, respectively. The direct uptake of Peramivir-(CH_2)_2-l-Val and Peramivirl-Ile in MDCK-PEPT1 cells were significantly higher than in MDCK mock cells, and could be markedly inhibited by gly-sar. The uptake of Peramivir-(CH_2)_2-l-Val and Peramivir-l-Ile(0.01 to 50 m M) in MDCK-hPEPT1 cells conformed to Michaelis–Menten Equation. The oral bioavailability of peramivir was 65.3% and 37.3% after the oral administration of Peramivir-(CH_2)_2-l-Val and Peramivir-l-Ile to rats, respectively. The oral absorption and bioactivation of Peramivir-(CH_2)_2-l-Val was rapid and extensive, and no Peramivir-(CH_2)_2-l-Val was found in plasma. Because the amide bond was relatively stable, Peramivir-l-Ile could not be totally converted to the parent drug in vivo. Peramivir-(CH_2)_2-l-Val with good oral profiles and rapid bioactivation might be a promising prodrug for the further clinic development. The present study also corroborated the idea that the PEPT1-mediated prodrug approach has enormous promise for improving the oral absorption of poorly absorbed drug.展开更多
16 ADT carboxylate esters were prepared by means of esterification and these compounds were expected to increase the bioavailability of 4-hydroxyanehole trithione.In vivo studies showed that ADT concentration of 3a in...16 ADT carboxylate esters were prepared by means of esterification and these compounds were expected to increase the bioavailability of 4-hydroxyanehole trithione.In vivo studies showed that ADT concentration of 3a in plasma was much higher than that of ATT during 120 min.Compound 3a could reach blood peak values of ADT at 660.6 ng/mL which was about 14 times of that by ATT.Additionally,the acute toxicity assay indicated high safety of compound 3a that the maximum tolerated dose was no less than 3.25 g/kg.展开更多
Highly water soluble esters of scutellarin with variable molecular weight polyethylene glycol （PEG） were prepared via PEGylation. The physicochemical properties and the stabilities under different conditions were in...Highly water soluble esters of scutellarin with variable molecular weight polyethylene glycol （PEG） were prepared via PEGylation. The physicochemical properties and the stabilities under different conditions were investigated. By PEG modification, the greatly increased water solubility and desirable partition coefficient of scuteUarin were obtained, and the results showed that these conjugates were potential prodrugs for the oral delivery of scuteUarin.展开更多
A simple and sensitive high performance liquid chromatography with fluorescence detection （HPLC-FD） has been developed for simultaneous quantification of doxorubicin （DOX） and its dipeptide conjugate prodrug （PDO...A simple and sensitive high performance liquid chromatography with fluorescence detection （HPLC-FD） has been developed for simultaneous quantification of doxorubicin （DOX） and its dipeptide conjugate prodrug （PDOX） in mice plasma. The chromatographic separation was carried out on an Amethyst C18-H column with gradient mobile phase of 0.1% formic acid and 0.1% formic acid in acetonitrile at a flow rate of 1.0 mL/min. The excitation and emission wavelengths were set at 490 and 550 nm, respectively. The method was comprehensively validated. The limits of detection were low up to 5.0 ng/mL for DOX and 25.0 ng/mL for PDOX. And the limits of quantification were low up to 12.5 ng/mL for DOX and 50 ng/mL for PDOX, which were lower than those for most of the current methods. The calibration curves showed good linearity （R2 〉 0.999） over the concentration ranges. The extraction recoveries ranged from 84.0% to 88.2% for DOX and from 85.4% to 89.2% for PDOX. Satisfactory intra-day and inter-day precisions were achieved with RSDs less than 9.1%. The results show that the developed HPLC-FD method is accurate, reliable and will be helpful for preclinical pharmacokinetic study of DOX and PDOX.展开更多
Ferroptosis is a new mode of cell death,which can be induced by Fenton reactionmediated lipid peroxidation.However,the insufficient H2O2 and high GSH in tumor cells restrict the efficiency of Fenton reaction-dependent...Ferroptosis is a new mode of cell death,which can be induced by Fenton reactionmediated lipid peroxidation.However,the insufficient H2O2 and high GSH in tumor cells restrict the efficiency of Fenton reaction-dependent ferroptosis.Herein,a self-supplying lipid peroxide nanoreactor was developed to co-delivery of doxorubicin(DOX),iron and unsaturated lipid for efficient ferroptosis.By leveraging the coordination effect between DOX and Fe3+,trisulfide bond-bridged DOX dimeric prodrug was actively loaded into the core of the unsaturated lipids-rich liposome via iron ion gradient method.First,Fe3+could react with the overexpressed GSH in tumor cells,inducing the GSH depletion and Fe2+generation.Second,the cleavage of trisulfide bond could also consume GSH,and the released DOX induces the generation of H2O2,which would react with the generated Fe2+in step one to induce efficient Fenton reaction-dependent ferroptosis.Third,the formed Fe3+/Fe2+couple could directly catalyze peroxidation of unsaturated lipids to boost Fenton reaction-independent ferroptosis.This iron-prodrug liposome nanoreactor precisely programs multimodal ferroptosis by integrating GSH depletion,ROS generation and lipid peroxidation,providing new sights for efficient cancer therapy.展开更多
In order to study the hydrolytic characterization of an anti-inflammatory prodrug （ RI-1 ） in vitro, an effective, accurate and reliable method for the simultaneous determination of the prodrug and its two hydrolyti...In order to study the hydrolytic characterization of an anti-inflammatory prodrug （ RI-1 ） in vitro, an effective, accurate and reliable method for the simultaneous determination of the prodrug and its two hydrolytic active compounds is developed using reverse phase high-performance liquid chromatography （RP-HPLC）. The chromatographic separation is performed on an ODS-2 C18 column （250 mm × 4. 6 mm, 5.0 μm particle size） with a simple elution program. The mobile phase is V（ methanol） ： V（0. 1% phosphoric acid solution） =90：10 （adjust pH to 2. 3）. A wavelength of 225 nm and a mobile phase flow rate of 1.0 mL/min are utilized for the quantitative analysis. Excellent linear behaviors over the investigated concentration ranges are observed with values of R2 higher than 0. 999 for all the analytes. The validated method is successfully applied to the simultaneous determination of the prodrug and its active components can be used to detect hydrolytic characterization in vitro.展开更多
Objective: To discuss the possibility of dexamethasone-dextran as a colon-specific dexamethasone prodrug. Methods: Dexamenthasone-dextran conjugate was synthesized with succinate as a cross-linker. The release of dexa...Objective: To discuss the possibility of dexamethasone-dextran as a colon-specific dexamethasone prodrug. Methods: Dexamenthasone-dextran conjugate was synthesized with succinate as a cross-linker. The release of dexamethasone was determined after the incubation of the prodrug with the contents of different parts of gastrointestinal(GI) tract of rats. Results: By HPLC analysis, it was shoWn that dexamethasone-dextran contained 9.2 mg dexamethasone per l00 mg dextran. conjugate. During 160 min incubation, the concentration of dexamethasone released in the contents of colon and cecum was 2.7 times as high as that released in the contents of proximal small intestine and distal small intestine. But no dexametha sone was released in the contents of stomach. Conclusion: Dexamethasone-dextran conjugate can be ed as a colon-specific dexamethasone prodrug to selectively deliver the drug to colon.展开更多
文摘The review provides an overview of the approaches, applications, and methods for ester prodrugs. Ester prodrugs are pharmacologically inactive compounds in their original form but become active drugs on biotransformation within the body, which offers advantages concerning the solubility, stability, and targeted delivery of the active drug. Several approaches of ester prodrugs have been reviewed in this review, including simple ester prodrugs, amino acid ester prodrugs, sugar ester prodrugs, lipid ester prodrugs, and polymeric ester prodrugs. This review incorporates in vitro and in vivo methods as well as the characterization of physical and chemical properties for ester prodrugs, cell culture systems, enzymatic assays, and animal models—all of these having a very important bearing on the evaluation of stability, bioavailability, and efficacy for ester prodrugs. While the benefits of using ester prodrugs are significant, there are also disadvantages like instability, poor or variable enzymatic hydrolysis, and toxicity from released promoieties or by-products. This review discusses solutions to the various limitations that include enhancing stability with ionizable promoieties and using physiologically-based pharmacokinetic modeling. The review also highlights the application of ester prodrugs in neurological disorders, such as Parkinson’s disease, and the ongoing efforts to address the critical limitations in treatment efficacy. Future prodrug strategies are poised to advance significantly by harnessing diverse transport mechanisms across the blood-brain barrier and integrating nanotechnology.
文摘Some Triptorelin<sup>®</sup> (TRP) conjugates of triphenylmethanol derivatives (TPMs) with optimized hydrophobicity were synthesized by reacting 2-substituted methoxy benzenes with 1,3,5-trioxane, followed by the conjugation with TRP and sebacic acid to produce TRP-TPMs derivatives. Comparative antiproliferative assays between TRP-TPMs conjugates and the corresponding non-covalent physical mixtures of the TPMs derivatives and TRP were used to treat human acute lymphoblastic leukemia (CCRF-CEM), human ovarian adenocarcinoma (SK-OV-3) and mouse preadipocytes (3T3-L1) cells. TRP-TPMs conjugates at the 50 μM inhibited cell proliferation in CCRF-CEM, SK-OV-3 and 3T3-L1 cells by 21% - 37%, 24% - 73%, 37% - 56%, respectively following incubation for 72 h. These findings indicate that TRP-TPMs derivatives have the potential to enhance the biological activity of TRP.
文摘Epidemiological studies indicate that treatment with metformin, an AMP-activated protein kinase (AMPK) activator, reduces the incidence of cancers. Activation of AMPK has also been reported to oppose tumor progression in diverse types of cancers and offers promising cancer therapy. Furthermore, AMPK is a primary regulator of energy metabolism and has also been implicated in cell cycle progression, angiogenesis, cell transformation, migration, and cancer. We have recently synthesized novel flavonoids, namely, triphenylmethanol derivatives (TPMs), but the effectiveness of the TPMs on the activity of AMPK remains unclear. We hypothesized that the novel TPMs would inhibit cancer cell proliferation through the activation of AMPK isoforms in cells. The effects of TPMs on prostate cells (PC-3) were investigated. Cells were exposed to TPMs for either 12 or 24 hr. at the respective doses of 0, 25, 50 100, and 200 µM based on the cell viability studies by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a tetrazole) (MTT) assay. The results indicate that cells exposed to the respective doses of TPMs increased both phospho- and total-AMPKα1 in a dose- and time-dependent manner. The effects of the increases for the phospho- and total-AMPKα in cells were greater for the 24-hr than the 12-hr. incubation. Further studies are currently going on to elucidate the specificities of the said insults in increasing the phospho- and total-AMPKα activities and for the other respective isoforms.
文摘Cancer enzymology is a promising filiation of bio-medical sciences. In thepast decades, enzymes, such as GST(glutathione S-transferase) , PKC(protein kinase C) , Topo(DNAtopoisomerases), TK(tyrosine kinase), CD (bacterial cytosine deaminase), CPG2(carboxypeptidase G2) ,and PNP (purine nucleoside phosphorylase), have been known to bear close relations to cancer. Theirspecific expression and influence on the process of tumor initiation, promotion and progressionattract scientists to apply them as a biochemical marker of certain malignant tumor, a predictor ofresponse in cancer chemotherapy; to apply them to drug design, tumor prevention and as adjuvant toradiotherapy or surgery.
基金supported by National Natural Science Founda-tion of China(81360485 and 81560577)National Natural Science Foundation of Jiangxi(20132BAB215023)
文摘Peramivir was a novel and highly potent neuraminidase(NA) inhibitor for the treatment of influenza A and B. However, it exhibited a very low oral bioavailability(only 3%) due to the high polarity(log P of-1.4) and the low membrane permeability across the intestine. To utilize the PEPT1-mediated prodrug strategy to improve the oral absorption and develop the oral alternative, seven amino acid ester prodrugs and seven amino acid amide prodrugs have been synthesized. The permeability of these prodrugs across Caco-2 cells were screened. Peramivr-(CH_2)_2-l-Val and Peramivir-l-Ile were of the highest permeability in ester prodrugs and amide prodrugs, respectively, and then they were selected for further studies. Glycylsarcosine(gly-sar) uptake by Caco-2 could be inbihited by Peramivir-(CH_2)_2-l-Val and Peramivir-l-Ile in a concentration-dependent manner, and the IC 50 was 1.34 ± 0.31 m M and 1.78 ± 0.48 m M, respectively. The direct uptake of Peramivir-(CH_2)_2-l-Val and Peramivirl-Ile in MDCK-PEPT1 cells were significantly higher than in MDCK mock cells, and could be markedly inhibited by gly-sar. The uptake of Peramivir-(CH_2)_2-l-Val and Peramivir-l-Ile(0.01 to 50 m M) in MDCK-hPEPT1 cells conformed to Michaelis–Menten Equation. The oral bioavailability of peramivir was 65.3% and 37.3% after the oral administration of Peramivir-(CH_2)_2-l-Val and Peramivir-l-Ile to rats, respectively. The oral absorption and bioactivation of Peramivir-(CH_2)_2-l-Val was rapid and extensive, and no Peramivir-(CH_2)_2-l-Val was found in plasma. Because the amide bond was relatively stable, Peramivir-l-Ile could not be totally converted to the parent drug in vivo. Peramivir-(CH_2)_2-l-Val with good oral profiles and rapid bioactivation might be a promising prodrug for the further clinic development. The present study also corroborated the idea that the PEPT1-mediated prodrug approach has enormous promise for improving the oral absorption of poorly absorbed drug.
文摘16 ADT carboxylate esters were prepared by means of esterification and these compounds were expected to increase the bioavailability of 4-hydroxyanehole trithione.In vivo studies showed that ADT concentration of 3a in plasma was much higher than that of ATT during 120 min.Compound 3a could reach blood peak values of ADT at 660.6 ng/mL which was about 14 times of that by ATT.Additionally,the acute toxicity assay indicated high safety of compound 3a that the maximum tolerated dose was no less than 3.25 g/kg.
基金supported by the National Natural Science Foundation of China(No.30070935,30271614)
文摘Highly water soluble esters of scutellarin with variable molecular weight polyethylene glycol （PEG） were prepared via PEGylation. The physicochemical properties and the stabilities under different conditions were investigated. By PEG modification, the greatly increased water solubility and desirable partition coefficient of scuteUarin were obtained, and the results showed that these conjugates were potential prodrugs for the oral delivery of scuteUarin.
基金supported by the National Natural Science Foundation of China (Grant nos. 21375101, 81573384 and 91417301)Natural Science Foundation of Hubei Province, China (No. 2014CFA077)Innovation Seed Fund and Translational Medical Research Fund of Wuhan University School of Medicine, China
文摘A simple and sensitive high performance liquid chromatography with fluorescence detection （HPLC-FD） has been developed for simultaneous quantification of doxorubicin （DOX） and its dipeptide conjugate prodrug （PDOX） in mice plasma. The chromatographic separation was carried out on an Amethyst C18-H column with gradient mobile phase of 0.1% formic acid and 0.1% formic acid in acetonitrile at a flow rate of 1.0 mL/min. The excitation and emission wavelengths were set at 490 and 550 nm, respectively. The method was comprehensively validated. The limits of detection were low up to 5.0 ng/mL for DOX and 25.0 ng/mL for PDOX. And the limits of quantification were low up to 12.5 ng/mL for DOX and 50 ng/mL for PDOX, which were lower than those for most of the current methods. The calibration curves showed good linearity （R2 〉 0.999） over the concentration ranges. The extraction recoveries ranged from 84.0% to 88.2% for DOX and from 85.4% to 89.2% for PDOX. Satisfactory intra-day and inter-day precisions were achieved with RSDs less than 9.1%. The results show that the developed HPLC-FD method is accurate, reliable and will be helpful for preclinical pharmacokinetic study of DOX and PDOX.
基金supported by the National Natural Science Foundation of China(no.81872816)the Liaoning Revitalization Talents Program(no.XLYC180801)+1 种基金China Postdoctoral Innovative Talents Support Program(no.BX20190219)China Postdoctoral Science Foundation(no.2019M661134).
文摘Ferroptosis is a new mode of cell death,which can be induced by Fenton reactionmediated lipid peroxidation.However,the insufficient H2O2 and high GSH in tumor cells restrict the efficiency of Fenton reaction-dependent ferroptosis.Herein,a self-supplying lipid peroxide nanoreactor was developed to co-delivery of doxorubicin(DOX),iron and unsaturated lipid for efficient ferroptosis.By leveraging the coordination effect between DOX and Fe3+,trisulfide bond-bridged DOX dimeric prodrug was actively loaded into the core of the unsaturated lipids-rich liposome via iron ion gradient method.First,Fe3+could react with the overexpressed GSH in tumor cells,inducing the GSH depletion and Fe2+generation.Second,the cleavage of trisulfide bond could also consume GSH,and the released DOX induces the generation of H2O2,which would react with the generated Fe2+in step one to induce efficient Fenton reaction-dependent ferroptosis.Third,the formed Fe3+/Fe2+couple could directly catalyze peroxidation of unsaturated lipids to boost Fenton reaction-independent ferroptosis.This iron-prodrug liposome nanoreactor precisely programs multimodal ferroptosis by integrating GSH depletion,ROS generation and lipid peroxidation,providing new sights for efficient cancer therapy.
文摘In order to study the hydrolytic characterization of an anti-inflammatory prodrug （ RI-1 ） in vitro, an effective, accurate and reliable method for the simultaneous determination of the prodrug and its two hydrolytic active compounds is developed using reverse phase high-performance liquid chromatography （RP-HPLC）. The chromatographic separation is performed on an ODS-2 C18 column （250 mm × 4. 6 mm, 5.0 μm particle size） with a simple elution program. The mobile phase is V（ methanol） ： V（0. 1% phosphoric acid solution） =90：10 （adjust pH to 2. 3）. A wavelength of 225 nm and a mobile phase flow rate of 1.0 mL/min are utilized for the quantitative analysis. Excellent linear behaviors over the investigated concentration ranges are observed with values of R2 higher than 0. 999 for all the analytes. The validated method is successfully applied to the simultaneous determination of the prodrug and its active components can be used to detect hydrolytic characterization in vitro.
文摘Objective: To discuss the possibility of dexamethasone-dextran as a colon-specific dexamethasone prodrug. Methods: Dexamenthasone-dextran conjugate was synthesized with succinate as a cross-linker. The release of dexamethasone was determined after the incubation of the prodrug with the contents of different parts of gastrointestinal(GI) tract of rats. Results: By HPLC analysis, it was shoWn that dexamethasone-dextran contained 9.2 mg dexamethasone per l00 mg dextran. conjugate. During 160 min incubation, the concentration of dexamethasone released in the contents of colon and cecum was 2.7 times as high as that released in the contents of proximal small intestine and distal small intestine. But no dexametha sone was released in the contents of stomach. Conclusion: Dexamethasone-dextran conjugate can be ed as a colon-specific dexamethasone prodrug to selectively deliver the drug to colon.
