Utilization of Sodium Nitroprusside as an Intestinal Permeation Enhancer for Lipophilic Drug Absorption Improvement in the Rat Proximal Intestine

As advanced synthetic technology has enabled drug candidate development with complex structure, resulting in low solubility and membrane permeability, the strategies to improve poorly absorbed drug bioavailability have attracted the attention of pharmaceutical companies. It has been demonstrated that nitric oxide (NO), a vital signaling molecule that plays an important role in various physiological systems, affects intestinal drug absorption. However, NO and its oxidants are directly toxic to the gastrointestinal tract, thereby limiting their potential clinical application as absorption enhancers. In this study, we show that sodium nitroprusside (SNP), an FDA-approved vasodilator, enhances the intestinal absorption of lipophilic drugs in the proximal parts of the small intestine in rats. The SNP pretreatment of the rat gastrointestinal sacs significantly increased griseofulvin and flurbiprofen permeation in the duodenum and jejunum but not in the ileum and colon. These SNP-related enhancement effects were attenuated by the co-pretreatment with dithiothreitol or c-PTIO, an NO scavenger. The permeation-enhancing effects were not observed in the case of antipyrine, theophylline, and propranolol in the duodenum and jejunum. Furthermore, the SNP treatment significantly increased acidic glycoprotein release from the mucosal layers specifically in the duodenum and jejunum but not in the ileum and colon. These results suggest that SNP increases lipophilic drug membrane permeability specifically in the proximal region of the small intestine through disruption of the mucosal layer.

Transformation of Iodosulfuron-Methyl into Ionic Liquids Enables Elimination of Additional Surfactants in Commercial Formulations of Sulfonylureas

Efficient use of herbicides for plant protection requires the application of auxiliary substances such as surfactants, stabilizers, wetting or anti-foaming agents, and absorption enhancers, which can be more problematic for environment than the herbicides themselves. We hypothesized that the combination of sulfonylurea (iodosulfuron-methyl) anion with inexpensive, commercially available quaternary tetraalkylammonium cations could lead to biologically active ionic liquids (ILs) that could become a convenient and environment-friendly alternative to adjuvants. A simple one-step synthesis allowed for synthesizing iodosulfuron-methyl based ILs with high yields ranging from 88 to 96% as confirmed by UV, FTIR, and NMR. The obtained ILs were found to possess several favorable properties compared to the currently used sodium salt iodosulfuron-methyl, such as adjustable hydrophobicity (octanol-water partition coefficient) and enhanced stability in aqueous solutions, which was supported by molecular calculations showing cation–anion interaction energies. In addition, soil mobility and volatility of ILs were more beneficial compared to the parental herbicide. Herbicidal activity tests toward oil-seed rape and cornflower revealed that ILs comprising at least one alkyl chain in the decyl to octadecyl range had similar or better efficacy compared to the commercial preparation without addition of any adjuvant. Furthermore, results of antimicrobial activity indicated that they were practically harmless or slightly toxic toward model soil microorganisms such as Pseudomonas putida and Bacillus cereus.

Effects of Transcutol P and Precirol ATO-5 on Percutaneous Absorption of Flutamide from Emulgels

Background: Flutamide is a non-steroidal anti-androgenic agent which is not only used in treating prostate cancer but also can be effective in some disorders such as androgenic alopecia and male pattern baldness. Several serious side effects for systemic administration of flutamide can be overcome by emulgel dosage form. Absorption enhancers can promote permeation of flutamide through skin. Percutaneous absorption of Flutamide emulgels with different concentrations of Transcutol P and Precirol ATO5 was studied. Methods: Various emulgel formulations using different concentration of Transcutol P and Precirol ATO5 with 0.5 to 5 % w/w were prepared. Percutaneous absorption was tested with standard Franz Diffusion Cell equipment using full thickness rat skin. Drug concentrations in the samples were analyzed by High-Performance Liquid Chromatography (HPLC) equipped with UV-Vis detector at 305 nm. Results: The percutaneous absorption of flutamide emulgels formulated with enhancers was higher than control formulations. Enhancement ratio increased from 1.218 to 3.670 and 1.346 to3.900 for Precirol ATO5 and Transcutol P, respectively. Area under the Curve (AUC) increased by increase the enhancers’ concentration and a significant upsurge was seen in the concentration 1% for both enhancers. Conclusion: The flutamide emulgel containing 1% Transcutol P showed more appropriate percutaneous absorption through the skin compared to others.

NMR-Guided Repositioning of Non-Steroidal Anti-Inflammatory Drugs into Tight Junction Modulators

Bioavailability is a major bottleneck in the clinical application of medium molecular weight therapeutics, including protein and peptide drugs. Paracellular transport of these molecules is hampered by intercellular tight junction (TJ) complexes. Therefore, safe chemical regulators for TJ loosening are desired. Here, we showed a potential application of select non-steroidal anti-inflammatory drugs (NSAIDs) as TJ modulators. Based on our previous observation that diclofenac and flufenamic acid directly bound various PDZ domains with a broad specificity, we applied solution nuclear magnetic resonance techniques to examine the interaction of other NSAIDs and the first PDZ domain (PDZ1) of zonula occludens (ZO)-1, ZO-1(PDZ1). Inhibition of ZO-1(PDZ1) is expected to provide loosening of the epithelial barrier function because the domain plays a crucial role in maintaining TJ integrity. Accordingly, diclofenac and indomethacin were found to decrease the subcellular localization of claudin (CLD)-2 but not occludin and ZO-1 at the apicolateral intercellular compartment of Madin–Darby canine kidney (MDCK) II cells. These NSAIDs exhibited 125–155% improved paracellular efflux of fluorescein isothiocyanate insulin for the Caco-2 cell monolayer. We propose that these NSAIDs can be repurposed as drug absorption enhancers for peptide drugs.

Gastrointestinal Region Specific Insulin Permeation Enhancement by Aloe vera Gel

Background: The oral administration route is still the most preferred by patients for drug treatment, but is unfortunately not suitable for all drug compounds. For example, protein and peptide drugs (e.g. insulin) are typically administered via injection seeing as they are unstable in the gastrointestinal luminal environment and have poor membrane permeation properties. To overcome this problem, functional excipients such as drug absorption enhancers can be co-administered. Although Aloe vera gel has the ability to improve the permeation of drugs across the intestinal epithelium, its drug permeation enhancing effect has not been investigated in the different regions of the gastrointestinal tract yet. Objective: The aim of this study was to investigate the insulin permeation enhancing effects of A. vera gel material across excised pig intestinal tissues from different regions of the gastrointestinal tract and to identify the gastrointestinal region where the highest insulin permeation enhancement was achieved. : Insulin transport across excised pig intestinal tissues from the duodenum, proximal jejunum, medial jejunum, distal jejunum, ileum and colon was measured in the absence and presence of A. vera gel (0.5% w/v) using both the Sweetana-Grass diffusion chamber and everted sac techniques. Results: The insulin permeation results obtained from both ex vivo techniques showed varied permeation enhancing effects of A. vera gel as a function of the different regions of the gastrointestinal tract. The colon was identified as the gastrointestinal region where A. vera gel was the most effective in terms of insulin permeation enhancement in the Sweetana-Grass diffusion chamber technique with a Papp value of 5.50 x 10-7 cm.s-1, whereas the ileum was the region where the highest permeation enhancement occurred in the everted sac technique with a Papp value of 5.45 x 10-7 cm.s-1. Conclusion: The gastrointestinal permeation enhancing effects of A. vera gel on insulin is region specific with the highest effect observed in the ileum and colon.