Synthesis and in vitro properties of prednisolone 21-sulfate sodium as a colon-specific prodrug of prednisolone

Glucocorticoids-based prodrug design: Current strategies and research progress

Attributing to their broad pharmacological effects encompassing anti-inflammation, antitoxin, and immunosuppression, glucocorticoids (GCs) are extensively utilized in the clinic for the treatment of diverse diseases such as lupus erythematosus, nephritis, arthritis, ulcerative colitis, asthma, keratitis, macular edema, and leukemia. However, long-term use often causes undesirable side effects, including metabolic disorders-induced Cushing's syndrome (buffalo back, full moon face, hyperglycemia, etc.), osteoporosis, aggravated infection, psychosis, glaucoma, and cataract. These notorious side effects seriously compromise patients' quality of life, especially in patients with chronic diseases. Therefore, glucocorticoid-based advanced drug delivery systems for reducing adverse effects have received extensive attention. Among them, prodrugs have the advantages of low investment, low risk, and high success rate, making them a promising strategy. In this review, we propose the strategies for the design and summarize current research progress of glucocorticoid-based prodrugs in recent decades, including polymer-based prodrugs, dendrimer-based prodrugs, antibody-drug conjugates, peptide-drug conjugates, carbohydrate-based prodrugs, aliphatic acid-based prodrugs and so on. Besides, we also raise issues that need to be focused on during the development of glucocorticoid-based prodrugs. This review is expected to be helpful for the research and development of novel GCs and prodrugs.

Optimizing Prednisolone Loading into Distiller's Dried Grain Kafirin Microparticles, and In vitro Release for Oral Delivery

Kafirin microparticles have potential as colon-targeted delivery systems because of their ability to protect encapsulated material from digestive processes of the upper gastrointestinal tract (GIT). The aim was to optimize prednisolone loading into kafirin microparticles, and investigate their potential as an oral delivery system. Response surface methodology (RSM) was used to predict the optimal formulation of prednisolone loaded microparticles. Prednisolone release from the microparticles was measured in simulated conditions of the GIT. The RSM models were inadequate for predicting the relationship between starting quantities of kafirin and prednisolone, and prednisolone loading into microparticles. Compared to prednisolone released in the simulated gastric and small intestinal conditions, no additional drug release was observed in simulated colonic conditions. Hence, more insight into factors affecting drug loading into kafirin microparticles is required to improve the robustness of the RSM model. This present method of formulating prednisolone-loaded kafirin microparticles is unlikely to offer clinical benefits over commercially available dosage forms. Nevertheless, the overall amount of prednisolone released from the kafirin microparticles in conditions simulating the human GIT demonstrates their ability to prevent the release of entrapped core material. Further work developing the formulation methods may result in a delivery system that targets the lower GIT.

Preclinical studies of the potent and selective nicotinic α4β2 receptor ligand VMY-2-95

The discovery and development of small molecules that antagonize neuronal nicotinic acetylcholine receptors may provide new ligands for evaluation in models of depression or addiction. We discovered a small molecule, VMY-2-95, a nAChR ligand with picomolar affinity and high selectivity for α4β2 receptors. In this study, we investigated its preclinical profile in regards to solubility, lipophilicity, metabolic stability, intestinal permeability, bioavailability, and drug delivery to the rat brain. Metabolic stability of VMY-2-95·2HCl was monitored on human liver microsomes, and specific activity of VMY-2-95·2HCl on substrate metabolism by CYP1A2, 2C9, 2C19, 2D6, and 3A4 was tested in a high-throughput manner. The intestinal transport of VMY-2-95·2HCl was studied through Caco-2 cell monolayer permeability. VMY-2-95·2HCl was soluble in water and chemically stable, and the apparent partition coefficient was 0.682. VMY-2-95·2HCl showed significant inhibition of CYP2C9 and 2C19, but weak or no effect on 1A2, 2D6, and 3A4. The Caco-2 cell model studies revealed that VMY-2-95·2HCl was highly permeable with efflux ratio of 1.11. VMY-2-95·2HCl achieved a maximum serum concentration of 0.56 mg/mL at 0.9 h and was orally available with a half-life of ∼9 h. Furthermore, VMY-2-95·2HCl was detected in the rat brain after 3 mg/kg oral administration and achieved a maximal brain tissue concentration of 2.3 μg/g within 60 min. Overall, the results demonstrate that VMY-2-95·2HCl has good drug like properties and can penetrate the blood–brain barrier with oral administration.

Preclinical studies of YK-4-272, an inhibitor of class II histone deacetylases by disruption of nucleocytoplasmic shuttling

PURPOSE

The HDAC shuttling inhibitor, YK-4-272 functions by restricting nuclear shuttling of Class II HDACs. Pre-clinical investigations of YK-4-272 bioavailability, pharmacokinetics, in vivo toxicity and tumor growth inhibition were performed to determine its potential as an HDAC shuttling disruptor for use in clinical applications.

METHODS

The solubility, lipophilicity, in vitro metabolic stability, in vitro intestinal permeability, and in vivo pharmacokinetics of YK-4-272 were determined by HPLC methods. The anti-tumor activity of YK-4-272 was determined by monitoring athymic Balb/c nude mice bearing PC-3 xenografts.

RESULTS

Oral bioavailability of YK-4-272 is supported by its solubility (0.537 mg/mL) and apparent partition coefficient of 2.0. The compound was chemically and metabolically stable and not a substrate for CYP450. In Caco-2 cell transport studies, YK-4-272 was highly permeable. The time-concentration profile of YK-4-272 in plasma resulted in a C ( max ) of 2.47 μg/mL at 0.25 h with a AUC of 3.304 μg × h/mL. Treatment of PC-3 tumor xenografts with YK-4-272 showed significant growth delay.

CONCLUSIONS

YK-4-272 is stable and bio-available following oral administration. Growth inhibition of cancer cells and tumors was observed. These studies support advancing YK-4-272 for further evaluation as a novel HDAC shuttling inhibitor for use in cancer treatment.

Study on the Colon Specific Delivery of Prednisolone Using Chitosan Capsules

In this study, we examined the effectiveness of chitosan capsules for the colon-specific delivery of prednisolone in rats. We also evaluated the effectiveness and side effects of prednisolone using chitosan capsules compared with the conventional dosage form (gelatin capsules). We found a significant increase in the concentration of prednisolone in the large intestinal mucosa when prednisolone was administered orally using chitosan capsules, as compared with the case using gelatin capsules. On the other hand, the plasma concentrations of prednisolone after oral administration using chitosan capsules were much lower than those in the case of gelatin capsules. We also assessed the effectiveness of prednisolone for the healing of trinitrobenzene sulfonic acid-induced colitis by measuring myeloperoxidase (MPO) activity and colon wet weight/body weight (C/B) ratio. MPO activities and C/B ratios were significantly reduced when prednisolone was administered orally using chitosan capsules, in comparison with the case of gelatin capsules. Moreover, the weight of the thymus, which is an index of the side effects of prednisolone, markedly decreased after oral administration of prednisolone using gelatin capsules, whereas its weight did not change as much when prednisolone was administered orally using chitosan capsules. These findings indicate that chitosan capsules might be useful for the colon-specific delivery of prednisolone and its enhanced effectiveness for the healing of colitis in rats. Moreover, chitosan capsules might be also effective in reducing the side effects of prednisolone due to its decreased intestinal transfer to the systemic circulation.

Novel drug delivery strategies for the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) encompasses two idiopathic inflammatory diseases of the intestinal tract: Crohn's disease and ulcerative colitis. Existing therapy for IBD consists mainly of orally or rectally administered small drug molecules, such as 5-aminosalicylates and corticosteroids, or potent systemic immune suppressants. IBD presents a challenging target for drug delivery, particularly by the oral route, as, contrary to most therapeutic regimens, minimal systemic absorption and maximal intestinal wall drug levels are desired. Several delivery strategies are employed to achieve this goal, including the chemical modification of the drug molecules, the use of controlled- and delayed-release formulations and the use of bioadhesive particles. The goal of this review is to summarise existing IBD therapy and examine novel approaches in intestinal drug delivery.