Development of a highly sensitive LC–MS/MS method for simultaneous determination of rupatadine and its two active metabolites in human plasma: Application to a clinical pharmacokinetic study

A single-dose, randomized, open-label, four-period, crossover equivalence trial comparing the clinical similarity of the proposed biosimilar rupatadine fumarate to reference Wystamm® in healthy Chinese subjects

Purpose

The aim of this study was to evaluate the bioequivalence of two formulations of rupatadine (10-mg tablets) under fasting and fed conditions in healthy Chinese subjects.

Methods

A total of 72 subjects were randomly assigned to the fasting cohort (n = 36) and fed cohort (n = 36). Each cohort includes four single-dose observation periods and 7-day washout intervals. Blood samples were collected at several timepoints for up to 72 h post-dose. The plasma concentration of rupatadine and the major active metabolites (desloratadine and 3-hydroxydesloratadine) were analyzed by a validated HPLC-MS/MS method. The non-compartmental analysis method was employed to determine the pharmacokinetic parameters. Based on the within-subject standard deviation of the reference formulation, a reference-scaled average bioequivalence or average bioequivalence method was used to evaluate the bioequivalence of the two formulations.

Results

For the fasting status, the reference-scaled average bioequivalence method was used to evaluate the bioequivalence of the maximum observed rupatadine concentration (Cmax; subject standard deviation > 0.294), while the average bioequivalence method was used to evaluate the bioequivalence of the area under the rupatadine concentration-time curve from time 0 to the last detectable concentration (AUC0-t) and from time 0 to infinity (AUC0-∞). The geometric mean ratio (GMR) of the test/reference for Cmax was 95.91%, and the upper bound of the 95% confidence interval was 95.91%. For AUC0-t and AUC0-∞ comparisons, the GMR and 90% confidence interval (CI) were 98.76% (93.88%-103.90%) and 98.71% (93.93%-103.75%), respectively. For the fed status, the subject standard deviation values of Cmax, AUC0-t, and AUC0-∞ were all <0.294; therefore, the average bioequivalence method was used. The GMR and 90% CI for Cmax, AUC0-t, and AUC0-∞ were 101.19% (91.64%-111.74%), 98.80% (94.47%-103.33%), and 98.63% (94.42%-103.03%), respectively. The two-sided 90% CI of the GMR for primary pharmacokinetic endpoints of desloratadine and 3-hydroxydesloratadine was also within 80%-125% for each cohort. These results met the bioequivalence criteria for highly variable drugs. All adverse events (AEs) were mild and transient.

Conclusion

The test drug rupatadine fumarate showed a similar safety profile to the reference drug Wystamm® (J. Uriach y Compañía, S.A., Spain), and its pharmacokinetic bioequivalence was confirmed in healthy Chinese subjects based on fasting and postprandial status.

Clinical trial registration

http://www.chinadrugtrials.org.cn/index.html, identifier CTR20213217.

Green quantitative spectrofluorometric analysis of rupatadine and montelukast at nanogram scale using direct and synchronous techniques

Two green-sensitive spectrofluorometric methods were investigated for assay of rupatadine (RUP) [method I] and its binary mixture with montelukast (MKT) [method II]. Method I depends on measuring native fluorescence of RUP in the presence of 0.10 M H2SO4 and 0.10%w/v sodium dodecyl sulfate at 455 nm after excitation at 277 nm. The range of the first method was 0.20-2.00 µg ml-1 with detection and quantitation limits of 59.00 and 179.00 ng ml-1, respectively. Method II depends on the first derivative synchronous spectrofluorometry. The derivative intensities were measured for the two drugs in an aqueous solution containing Mcllvaine's buffer pH 2.60 at fixed Δλ of 140 nm. Each drug was estimated at zero-contribution of the other. The intensity was measured at 261 and 371 nm for RUP and MKT, respectively. The method was linear over 0.10-4.00 and 0.20-1.60 µg ml-1 with limits of detection 31.00 and 66.00 ng ml-1 and limits of quantitation 94.00 and 200.00 ng ml-1 for RUP and MKT, respectively. The method was extended to determine this mixture in laboratory-prepared mixtures and combined tablets. Method validation was performed according to ICH guidelines. Statistical interpretation of data revealed good agreement with the comparison method. Method greenness was confirmed by applying three different assessment tools.

Insights into the metabolic characteristics of aminopropanediol analogues of SYLs as S1P1 modulators: from structure to metabolism

SYL927 and SYL930, two aminopropanediol analogues, are novel Sphingosine-1-phosphate receptor 1 (S1P₁) modulators with higher selectivity and pharmacological activity compared with FTY720. Although the immunosuppressive activity of SYLs has been well demonstrated, information regarding the metabolic fates of the two chemicals is limited except for the CYP-catalyzed hydroxylation of SYL930. In this study, the biotransformation schemes of the two promising chemicals were investigated and compared using liver microsomes, S9 fractions and recombinant enzymes, and relevant molecular mechanism was primarily demonstrated by ligand-enzyme docking analysis (CDOCKER). As a result, the hydroxylation at alkyl chain on oxazole ring by the action of CYPs was found for both SYLs in vivo. The SULT-catalyzed sulfonation of the hydroxide was observed for SYL927 while the ADH/ALDH-catalyzed oxidation was only discovered for SYL930. The docking analysis suggested that specific non-covalent forces and/or bonding conformations of the hydroxides with biomacromolecules might be involved in the disparate metabolism of SYLs. Exploring the metabolic characteristics will help clarify the substance base for efficacy and safety of the two drugs. The uncovered structure-metabolism relationship in this study may provide an implication for the design and optimization for other S1P modulators.

Resonance Rayleigh scattering and spectrofluorimetric approaches for the selective determination of rupatadine using erythrosin B as a probe: application to content uniformity test

In this study, spectrofluorimetric and resonance Rayleigh scattering techniques were applied for the first time for determination of rupatadine through two validated methods. The proposed methods were based on a facile association complex formation between rupatadine and erythrosin B reagent in acidic medium. Spectrofluorimetric determination relied on the quenching effect of rupatadine on the fluorescence intensity of erythrosin B at 556 nm (excitation = 530 nm). Conversely, the resonance Rayleigh scattering (RRS) method relied on enhancement in the resonance Rayleigh scattering spectrum of erythrosin B at 344 nm after the addition of rupatadine. The developed methods produced linear results over ranges 0.15-2.0 μg/ml and 0.1-1.5 μg/ml, with detection limits of 0.030 μg/ml and 0.018 μg/ml for the spectrofluorimetric method and the RRS method, respectively. All reaction conditions for rupatadine-erythrosin B formation were optimized experimentally and both methods were validated according to International Council for Harmonisation guidelines. The developed methods were applied to estimate rupatadine content in its pharmaceutical tablet dosage form with acceptable recoveries. Furthermore, a content uniformity test for the commercial rupatadine tablets was successfully applied by the suggested spectroscopic methods according to United States Pharmacopeia guidelines.

Pharmacokinetics and Tissue Distribution of Loratadine, Desloratadine and Their Active Metabolites in Rat based on a Newly Developed LC-MS/MS Analytical Method

Loratadine (LOR) and its major metabolite, desloratadine (DL) are new-generation antihistamines. The hydroxylated metabolites of them, 6-OH-DL, 5-OH-DL and 3-OH-DL are also active because of their ability to inhibit binding of pyrilamine to brain H₁ receptors and a tendency for distributing to specific immune-regulatory tissues. In this study, a new validated LC-MS/MS method to simultaneously quantify LOR, DL, 6-OH-DL, 5-OH-DL and 3-OH-DL in plasma and tissues was established and applied to an investigation of their pharmacokinetics and target-tissue distribution tendency for the first time. Pharmacokinetics parameters in rat were measured and the results suggest that the body's exposure to active metabolites were much higher than to the prodrug with LOR, but much lower with DL. The tissue distribution study shows that LOR, DL and their active metabolites were widely distributed in the liver, spleen, thymus, heart, adrenal glands and pituitary gland. For immune-regulatory tissues, the concentrations of LOR, DL and their active metabolites in the spleen were much higher than in the thymus, which is related to the spleen, one of the sites where immune responses occur. LOR and its metabolites might inhibit immune-mediated allergic inflammation through the hypothalamic-pituitary-adrenal (HPA) axis. It was also found that the concentration of LOR in the heart was highest after liver and adrenal glands while those of DL, 6-OH-DL and 5-OH-DL in the liver, adrenal glands and spleen were all higher than those in the heart, which suggests that LOR may have a greater tendency to distribute in the heart than its metabolites.

Route to Prolonged Residence Time at the Histamine H1 Receptor: Growing from Desloratadine to Rupatadine

Drug–target binding kinetics are an important predictor of in vivo drug efficacy, yet the relationship between ligand structures and their binding kinetics is often poorly understood. We show that both rupatadine (1) and desloratadine (2) have a long residence time at the histamine H₁ receptor (H₁R). Through development of a [³H]levocetirizine radiolabel, we find that the residence time of 1 exceeds that of 2 more than 10-fold. This was further explored with 22 synthesized rupatadine and desloratadine analogues. Methylene-linked cycloaliphatic or β-branched substitutions of desloratadine increase the residence time at the H₁R, conveying a longer duration of receptor antagonism. However, cycloaliphatic substituents directly attached to the piperidine amine (i.e., lacking the spacer) have decreased binding affinity and residence time compared to their methylene-linked structural analogues. Guided by docking studies, steric constraints within the binding pocket are hypothesized to explain the observed differences in affinity and binding kinetics between analogues.

Investigation of the cytotoxicity, apoptosis and pharmacokinetics of Raddeanin A

Raddeanin A, one of the triterpenoid saponins extracted from Anemone raddeana rhizome of the Ranunculaceae family, has demonstrated the ability to inhibit the growth of human hepatic and gastric cancer cells. However, the effects of Raddeanin A on human colon cancer cells have not been investigated extensively. The present study aimed to examine the antiproliferative and apoptosis-inducing effects of Raddeanin A on the HCT-116 human colon cancer cell line in vitro, and evaluate the pharmacokinetic and biodistribution properties of Raddeanin A in mice following a single oral administration. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to assess the in vitro cytotoxicity of Raddeanin A against HCT-116 cells. 4',6-Diamidino-2-phenylindole, dihydrochloride staining and flow cytometry were performed to further examine the apoptosis-inducing capability of Raddeanin A. The concentrations of Raddeanin A in the plasma and tissues were analyzed using liquid chromatography-tandem mass spectrometry. Raddeanin A showed a dose-dependent antiproliferative effect towards the HCT-116 cells, with a half maximal inhibitory concentration of ~1.4 µM. Treatment with Raddeanin A resulted in a significant induction of apoptosis, observed as apparent morphological changes of the nuclei, with a total apoptotic ratio of 41.8% at a concentration of 3 µM. Low concentrations of Raddeanin A were detected in the heart, liver, spleen, lung, kidney and plasma of the mice following oral administration, however, the majority of the Raddeanin A was distributed in the intestinal tract, particularly in the colon and caecum. These present study confirmed the growth-inhibitory and apoptosis-inducing effects of Raddeanin A on HCT-116 cells and performed preliminary examinations of its pharmacokinetic properties, which provide a foundation for further investigating the inhibitory mechanism on the colon cancer cells in vivo.

Comparative efficacy of bilastine, desloratadine and rupatadine in the suppression of wheal and flare response induced by intradermal histamine in healthy volunteers

OBJECTIVE

To compare the peripheral antihistaminic activity of bilastine, rupatadine and desloratadine in inhibiting the histamine-induced wheal and flare (W&F) response.

RESEARCH DESIGN AND METHODS

Twenty-four healthy volunteers aged 18-40 years participated in this crossover, randomized, double-blind, placebo-controlled clinical study. Subjects received single doses of bilastine 20 mg, desloratadine 5 mg, rupatadine 10 mg and placebo. W&F responses induced by intradermal injection of histamine 5 μg were evaluated before treatment (basal value) and at 0.5, 1, 2, 4, 6, 9, 12 and 24 hours after treatment. Fifteen minutes after histamine injection, W&F surface areas (cm²) were quantified using the Visitrak System. Itching sensation was evaluated using a 100 mm visual analog scale. EudraCT number: 2015-000790-13.

MAIN OUTCOME MEASURES

The primary outcome measure was the percentage reduction in W&F areas after each active treatment compared with corresponding basal values.

RESULTS

Bilastine induced the greatest inhibition in wheal area and was significantly superior to desloratadine and rupatadine from 1 to 12 hours (both p < .001). Rupatadine and desloratadine were better than placebo without differences between them. Maximum wheal inhibition occurred at 6 hours (bilastine 83%, desloratadine 38%, rupatadine 37%). Onset of action was 1 hour for bilastine and 4 hours for desloratadine and rupatadine. Bilastine was significantly superior to desloratadine and rupatadine for flare inhibition from 1-24 hours (both p < .001) with an onset of action at 30 minutes. Bilastine was significantly better than desloratadine (2-12 hours; at least p < .05) and rupatadine (2-9 hours; at least p < .01) for reducing itching sensation. Neither desloratadine nor rupatadine significantly reduced itching compared to placebo. All active treatments were well tolerated.

CONCLUSIONS

Bilastine 20 mg induced significantly greater inhibition of the W&F response compared with desloratadine 5 mg and rupatadine 10 mg throughout the 24 hour study period, and had the fastest onset of action. Only bilastine significantly reduced itching sensation versus placebo.

Treatment of allergic rhinitis and urticaria: a review of the newest antihistamine drug bilastine

Allergic rhinitis and urticaria are common allergic diseases that may have a major negative impact on patients' quality of life. Bilastine, a novel new-generation antihistamine that is highly selective for the H1 histamine receptor, has a rapid onset and prolonged duration of action. This agent does not interact with the cytochrome P450 system and does not undergo significant metabolism in humans, suggesting that it has very low potential for drug-drug interactions, and does not require dose adjustment in renal impairment. As bilastine is not metabolized and is excreted largely unchanged, hepatic impairment is not expected to increase systemic exposure above the drug's safety margin. Bilastine has demonstrated similar efficacy to cetirizine and desloratadine in patients with seasonal allergic rhinitis and, in a Vienna Chamber study, a potentially longer duration of action than fexofenadine in patients with asymptomatic seasonal allergic rhinitis. It has also shown significant efficacy (similar to that of cetirizine) and safety in the long-term treatment of perennial allergic rhinitis. Bilastine showed similar efficacy to levocetirizine in patients with chronic spontaneous urticaria and can be safely used at doses of up to fourfold higher than standard dosage (80 mg once daily). The fourfold higher than standard dose is specified as an acceptable second-line treatment option for urticaria in international guidelines. Bilastine is generally well tolerated, both at standard and at supratherapeutic doses, appears to have less sedative potential than other second-generation antihistamines, and has no cardiotoxicity. Based on its pharmacokinetic properties, efficacy, and tolerability profile, bilastine will be valuable in the management of allergic rhinitis and urticaria.