Pharmacokinetics of uridine following ocular, oral and intravenous administration in rabbits

Uridine Derivatives: Synthesis, Biological Evaluation, and In Silico Studies as Antimicrobial and Anticancer Agents

Nucleoside analogs are frequently used in the control of viral infections and neoplastic diseases. However, relatively few studies have shown that nucleoside analogs have antibacterial and antifungal activities. In this study, a fused pyrimidine molecule, uridine, was modified with various aliphatic chains and aromatic groups to produce new derivatives as antimicrobial agents. All newly synthesized uridine derivatives were analyzed by spectral (NMR, FTIR, mass spectrometry), elemental, and physicochemical analyses. Prediction of activity spectra for substances (PASS) and in vitro biological evaluation against bacteria and fungi indicated promising antimicrobial capability of these uridine derivatives. The tested compounds were more effective against fungal phytopathogens than bacterial strains, as determined by their in vitro antimicrobial activity. Cytotoxicity testing indicated that the compounds were less toxic. In addition, antiproliferative activity against Ehrlich ascites carcinoma (EAC) cells was investigated, and compound 6 (2',3'-di-O-cinnamoyl-5'-O-palmitoyluridine) demonstrated promising anticancer activity. Their molecular docking against Escherichia coli (1RXF) and Salmonella typhi (3000) revealed notable binding affinities and nonbonding interactions in support of this finding. Stable conformation and binding patterns/energy were found in a stimulating 400 ns molecular dynamics (MD) simulation. Structure-activity relationship (SAR) investigation indicated that acyl chains, CH₃(CH₂)₁₀CO-, (C₆H₅)₃C-, and C₂H₅C₆H₄CO-, combined with deoxyribose, were most effective against the tested bacterial and fungal pathogens. Pharmacokinetic predictions were examined to determine their ADMET characteristics, and the results in silico were intriguing. Finally, the synthesized uridine derivatives demonstrated increased medicinal activity and high potential for future antimicrobial/anticancer agent(s).

Ocular Biodistribution of Once-Daily 0.6% Bilastine Eye Drops Reveals Highest Levels in Conjunctiva Up to 24 h Postadministration

Purpose: Bilastine is a second-generation antihistamine that has been shown to be effective for treatment of allergic conjunctivitis. The objective of this study was to evaluate the pharmacokinetics (PKs) and biodistribution of 0.6% bilastine preservative-free eye drops. Methods: Bilastine was quantified in the conjunctiva, cornea, aqueous humor, vitreous humor, iris/ciliary body, retina/choroid, crystalline lens, and plasma, following a single topical administration to male Dutch-belted rabbits. Results: Concentrations of bilastine were highest in the conjunctiva [C_max: 2,545.04 ng/g, at 6 h postadministration; area under the concentration-time curve (AUC_t): 11,382.40 ng·h/g] and cornea (C_max: 609.11 ng/g, at 1 h postadministration; AUC_t: 1,993.88 ng·h/g), followed by the iris/ciliary body, retina/choroid, aqueous humor, plasma, vitreous humor, and crystalline lens. Quantifiable bilastine concentrations were observed up to 24 h after instillation in the conjunctiva (388.45 ng/g), cornea (28.68 ng/g), iris/ciliary body (12.42 ng/g), retina/choroid (1.91 ng/g), and crystalline lens (0.12 ng/g). In plasma, aqueous humor, and vitreous humor, bilastine was detected up to 12 h postadministration (0.18 ng/mL, 0.40 ng/mL, and 0.32 ng/g, respectively). Conclusions: PKs and biodistribution of 0.6% bilastine eye drops in rabbits revealed a marked preferential distribution in the conjunctiva (target tissue), with sustained levels up to 24 h. These findings are consistent with clinical efficacy trials supporting once-daily administration of topical bilastine for treatment of allergic conjunctivitis.

A Set of Global Metabolomic Biomarker Candidates to Predict the Risk of Dry Eye Disease

Purpose

We used ultraperformance liquid chromatography coupled with quadrupole/time-of-flight tandem mass spectrometry (UPLC-Q/TOF-MS/MS) to analyze the metabolic profile of reflex tears obtained from patients with dry eye disorders.

Methods

We performed a cross-sectional study involving 113 subjects: 85 patients diagnosed with dry eye syndrome (dry eye group) and 28 healthy volunteers (control group). Reflex tears (20–30 μl) were collected from the tear meniscus of both eyes of each subject using a Schirmer I test strip. MS data were acquired with a standard workflow by UPLC-Q/TOF-MS/MS. Metabolites were quantitatively analyzed and matched with entries in the Metlin, Massbank, and HMDB databases. Least absolute shrinkage and selection operator (LASSO) regression was conducted to detect important metabolites. Multiple logistic regression was used to identify the significant metabolic biomarker candidates for dry eye syndrome. Open database sources, including the Kyoto Encyclopedia of Genes and Genomes and MetaboAnalyst, were used to identify metabolic pathways.

Results

After the LASSO regression and multiple logistic regression analysis, 4 of 20 metabolic biomarker candidates were significantly correlated with Ocular Surface Disease Index score, 42 of 57 with fluorescein breakup time, and 26 of 57 with fluorescein staining. By focusing on the overlap of these three sets, 48 of 51 metabolites contributed to the incidence of dry eye and there were obvious changes in different age groups. Metabolic pathway analysis revealed that the main pathways were glucose metabolism, amino acid metabolism, and glutathione metabolism.

Conclusion

Dry eye syndrome induces changes in the metabolic profile of tears, and the trend differs with age. This evidence reveals the relationship between changes in metabolites, symptoms of dry eye syndrome, and age.

Calculation of a First-In-Man Dose of 7-O-Succinyl Macrolactin A Based on Allometric Scaling of Data from Mice, Rats, and Dogs

7-O-Succinyl macrolactin A (SMA) exerts several pharmacological effects including anti-bacterial, anti-inflammation, and anti-cancer activities. Recently, SMA has been extensively evaluated as an anti-cancer drug. Thus, the objectives of the present study were to characterise the pharmacokinetics of SMA via both non-compartmental and compartmental analysis in mice, rats, and dogs, and to derive an appropriate first-in-man dose based on allometric scaling of the animal data. The time courses of plasma SMA concentrations after intravenous administration to rats and dogs were analysed retrospectively, as were data collected after intraperitoneal SMA injection in mice. Pharmacokinetic parameters were estimated via both noncompartmental and compartmental analysis, and were correlated with body weight and/or the potential maximum life-span. The clearance and distribution volume of SMA in humans were predicted, and a first-in-man dose proposed. A two-compartment model best described the time courses of SMA plasma concentrations after a saturation elimination process was applied to fit the dataset obtained from rats. Incorporation of the maximum potential life-span during allometric scaling was required to improve the estimation of human clearance. The SMA clearance and the distribution volume in the steady state, in a 70-kg adult male, were estimated to be 30.6 L/h and 19.5 L, respectively. To meet the area under the curve (AUC) required for anti-tumour activity, a dose of 100 mg (∼1.5 mg/kg) was finally proposed as the first dose for a 70-kg human. Although toxicological profiles derived from non-clinical studies must be considered before any final decision is made, our work will facilitate clinical studies on SMA.

Uridine supplementation exerts anti-inflammatory and anti-fibrotic effects in an animal model of pulmonary fibrosis

Rationale

Pulmonary fibrosis is a progressive disease with only few treatment options available at the moment. Recently, the nucleoside uridine has been shown to exert anti-inflammatory effects in different animal models, e.g. in acute lung injury or bronchial asthma.

Method

Therefore, we investigated the influence of uridine supplementation on inflammation and fibrosis in the classical bleomycin model. Male C57BL/6 mice received an intratracheal injection of bleomycin on day 0 and were treated intraperitoneally with uridine or vehicle. The degree of inflammation and fibrosis was assessed at different time points.

Results

Uridine administration resulted in attenuated inflammation, as demonstrated by reduced leukocytes and pro-inflammatory cytokines in the broncho-alveolar lavage (BAL) fluid. Furthermore, collagen deposition in the lung interstitium was also reduced by uridine supplementation. Similar results were obtained in a model in which animals received repeated intraperitoneal bleomycin injections. In addition uridine inhibited collagen and TGF-ß synthesis by primary lung fibroblasts, the release of pro-inflammatory cytokines by human lung epithelial cells, as well as the production of reactive oxygen species by human neutrophils.

Conclusion

In summary, we were able to show that uridine has potent anti-inflammatory and anti-fibrotic properties. As uridine supplementation has been shown to be well tolerated and safe in humans, this might be a new therapeutic approach for the treatment of fibrotic lung diseases.