Roxatidine acetate. A review of its pharmacodynamic and pharmacokinetic properties, and its therapeutic potential in peptic ulcer disease and related disorders

N-Benzyl piperidine Fragment in Drug Discovery

The N-benzyl piperidine (N-BP) structural motif is commonly employed in drug discovery due to its structural flexibility and three-dimensional nature. Medicinal chemists frequently utilize the N-BP motif as a versatile tool to fine-tune both efficacy and physicochemical properties in drug development. It provides crucial cation-π interactions with the target protein and also serves as a platform for optimizing stereochemical aspects of potency and toxicity. This motif is found in numerous approved drugs and clinical/preclinical candidates. This review focuses on the applications of the N-BP motif in drug discovery campaigns, emphasizing its role in imparting medicinally relevant properties. The review also provides an overview of approved drugs, the clinical and preclinical pipeline, and discusses its utility for specific therapeutic targets and indications, along with potential challenges.

Binding ability of roxatidine acetate and roxatidine acetate supported chitosan nanoparticles towards bovine serum albumin: characterization, spectroscopic and molecular docking studies

The RxAc drug loaded on Tween80-chitosan-TPP nanoparticles (NRxAc) has been characterized and probed by UV-Vis, PXRD, FTIR, DLS and SEM technique. The physicochemical characteristics of NRxAc have been employed and evaluated for formulation of drug, particle size, external morphology, drug content and in vitro drug release. Multi-spectroscopic (i.e. fluorescence, UV-Vis, CD spectroscopy) and molecular docking techniques were also used to study the interaction of BSA with RxAc and NRxAc. RxAc and NRxAc quenched the fluorescence emission of BSA via a static quenching mechanism. The experimental data of Fluorescence demonstrated that the binding constant of RxAc and NRxAc were found around 10⁴ L.mol^-1, which suggests moderate binding affinity with BSA via hydrophobic forces. Through the site marker displacement experiments and molecular docking, the probable binding location of RxAc and NRxAc has been suggested in subdomain IB (site III) of BSA. Altogether, the results of present study can provide an important insight and a great deal of helpful information for future design of antiulcer drugs. Hence, The RxAc-loaded chitosan nanoparticles produced might be utilized as a successful tool for developing and using antiulcer drugs.Communicated by Ramaswamy H. Sarma.

Antiulcerogenic and healing activity of hecogenin acetate in rodents

Peptic ulcers are lesions in the gastric and duodenal mucosa generated by an imbalance between protective factors (gastroduodenal mucus secretion, bicarbonate production, adequate blood flow) and harmful factors (excess pepsin or hydrochloric acid). Some drugs used in peptic ulcer therapy are associated with adverse effects. The aim of this study was to evaluate the antiulcerogenic and healing activity of hecogenin acetate (HA) in acute and chronic models of gastric lesions in rodents. The antiulcerogenic activity of HA was evaluated in models of gastric lesions induced by absolute ethanol and in acidified ethanol with HA (5, 10, and 20 mg/kg). For the model of gastric lesions induced by ischemia and reperfusion, rats were pre-treated with HA (5, 10, 20 mg/kg). After that, they were submitted to 30 min of ischemia, followed by 1 h of reperfusion. To evaluate the healing activity was induced gastric ulcer using acetic acid (80%) in rats. After 24 h, they were treated for 7 consecutive days with HA (10 and 20 mg/kg). They were evaluated the possible signs of toxicity, measurement of the lesions, collagen deposition, and histological analysis. HA significantly reduced the area of the lesion in models of gastric lesions induced by absolute and acidified ethanol, ischemia-induced gastric lesions and reperfusion, and regarding healing. In the collagen deposition, the presence and increase of collagen demonstrate the healing effect. The AH has antiulcerogenic and healing potential demonstrated by the decrease in gastric injury and presence of collagen fibers, respectively.

New Potential of Roxatidine Acetate Hydrochloride on Atopic Dermatitis Mouse Model, Human Keratinocytes, and Human Skin Equivalent Model

Atopic dermatitis (AD) is a complex inflammatory skin disorder, characterized by a complicated pathophysiology and a wide range of clinical phenotypes. Roxatidine acetate chloride (RXA) is a precursor of Roxatidine and a histamine H₂ receptor antagonist, used for the treatment of gastric ulcers. In this study, we aimed to examine whether RXA had anti-AD effects and determine the underlying molecular mechanism of RXA. The anti-AD effects were examined in Dermatophagoides farinae body (Dfb)-induced AD mouse model, tumor necrosis factor (TNF)-α/interferon (IFN)-γ-stimulated HaCaT keratinocytes, and human skin equivalent model using ELISA, histological analysis, immunohistochemistry, Western blot, and immunofluorescence. Results showed that RXA treatment significantly alleviated Dfb-induced AD skin symptoms and clinical severity in mice by decreasing the levels of immunoglobulin E, histamine, and inflammatory cytokines. RXA effectively inhibited the expression of adhesive molecules and recovered the filaggrin expression in Dfb-induced AD skin lesions and TNF-α/IFN-γ-stimulated HaCaT keratinocytes. Additionally, RXA significantly upregulated the expression of aryl hydrocarbon receptor and sirtuin1. The anti-AD effects of RXA were associated with suppressed nuclear factor kappa cascade. Overall, our results suggest that RXA may be a potential anti-AD candidate owing to its inhibitory effect against skin inflammation and protection of the skin barrier function in AD.

Pharmacokinetics and Bioequivalence Studies of Roxatidine Acetate Hydrochloride Sustained-Release Capsule in Healthy Chinese Subjects

This study aimed to evaluate the bioequivalence between a generic roxatidine acetate hydrochloride (RAH) sustained-release capsule and brand-named formulation (ALTAT) under fasting and fed conditions. An open-label, single-center, randomized 2-period crossover study with a 5-day washout period was conducted. A single oral dose of 75-mg generic RAH sustained-release capsule (test drug) or a commercial capsule (reference drug) was given to healthy volunteers under fasting (n = 36) and fed conditions (n = 36). Blood samples were collected at baseline and during the 24 hours after dosing. The concentrations of roxatidine acetate (ROX) and bioactive metabolite roxatidine in plasma were detected using a validated high-performance liquid chromatography-tandem mass spectrometry method. Pharmacokinetic parameters were analyzed with noncompartmental methods. As prodrug, RAH was dehydrochloric acid to ROX in body and further rapidly converted to roxatidine. Such a rapid metabolism resulted in ROX that was hardly detected in plasma. Active metabolism roxatidine was therefore used to evaluate the pharmacokinetic process. The major pharmacokinetic parameters of roxatidine including peak plasma concentration, area under the plasma concentration-time curve from time 0 to time t, and area under the plasma concentration-time curve from time 0 to infinity were similar between the 2 preparations under fasting and fed conditions. The generic RAH sustained-release capsule is bioequivalent to the reference drug under fasting and fed conditions in healthy Chinese subjects.

Phenoxypropylamines: Synthesis and Antiulcer Evaluation

We have synthesized a number of phenoxypropylamines from N-{3-[3-(1-piperidinylmethyl)phenoxy]propyl}chloroacetamide (3). All the products have been characterized by elemental analysis, ¹H-NMR and MS. The biological activity effects of the title compounds were examined. From the biological activity results, we found that two of them showed significant gastric acid antisecretory activity.

Determination of roxatidine in human plasma by liquid chromatography/electrospray mass spectrometry and application to a clinical pharmacokinetic study

A rapid and sensitive liquid chromatography/mass spectrometry (LC/MS) method was developed and validated for the determination of roxatidine in human plasma. Roxatidine was extracted by single liquid-liquid extraction with tert-butyl methyl ether, and the chromatographic separation was performed on a C8 column. The total analytical run time was relatively short (5 min), and the limit of assay quantification was 2 ng/mL using 0.1 mL of human plasma. Roxatidine and the internal standard, propranolol, were monitored in selected ion monitoring (SIM) mode at m/z 307.3 and 260.3, respectively. The standard curve was linear over a concentration range from 2-500 ng/mL, and the correlation coefficients were >0.999. The mean intra- and inter-day assay accuracy ranged from 103.4-108.8% and 102.3-110.0%, respectively, and the mean intra- and inter-day precision was between 3.3-8.8% and 5.3-6.2%, respectively. The developed assay method was successfully applied to a pharmacokinetic study in human volunteers after oral administration of roxatidine acetate hydrochloride at a dose of 75 mg.

Histamine H2-receptor antagonism of T-593: studies on positive chronotropic responses in guinea pig atria

Histamine H2-antagonistic properties of the novel H2-antagonist T-593, (+-)-N-[2-hydroxy-2-(4-hydroxyphenyl)ethyl]-N'-[2- [[[5-(methylamino)methyl-2-furyl]methyl]thio]ethyl]-N"- (methylsulfonyl) guanidine were investigated on the histamine-induced positive chronotropic responses in isolated guinea pig right atria. T-593 at 3 x 10(-7)-3 x 10(-6) M suppressed the maximal responses of the histamine concentration-response curves in a concentration-dependent fashion, indicating that T-593 is an unsurmountable antagonist. The pD'2 values were 5.50 for T-593 and 5.61 for famotidine; and the IC50 values at 1 x 10(-5) M histamine were 1.05 x 10(-6) M for T-593, 1.59 x 10(-6) M for ranitidine and 1.67 x 10(-7) M for famotidine. T-593 is a racemic compound composed of two enantiomers, (-)-T-593 and (+)-T-593. The histamine H2-antagonistic activity of (-)-T-593 was 1.5-fold more potent than that of racemic T-593, but (+)-T-593 scarcely inhibited the histamine-induced positive chronotropic response. Histamine H2-antagonism by racemic T-593 was mainly attributed to (-)-T-593. Isoproterenol-induced positive chronotropic responses were not affected by T-593 even at 3 x 10(-5) M. Pretreatment of ranitidine for 10 min prior to application of T-593 protected H2-receptors from unsurmountable antagonism by T-593. Reversibility of H2-antagonism was determined every 1 hr after a 30-min treatment of H2-antagonists. T-593 inhibited the positive chronotropic responses for over 6 hr in contrast to fast recovery from inhibition by ranitidine or famotidine. This result showed that T-593 is a slowly dissociable, long-acting histamine H2-antagonist.

Prescribing policy for antiulcer treatment in the elderly

In the short and long term treatment of peptic ulcer in the elderly some problems have yet to be resolved, mainly concerning the physiology and pathophysiology of the aging stomach, the pharmacokinetic and pharmacodynamic properties of antiulcer drugs, and the presence of different risk factors compared with young patients. The available data from controlled trials of peptic ulcer in the general population and from the limited experience in geriatrics, show that the clinical efficacy and tolerability of the anti-secretory drugs (e.g. cimetidine, ranitidine and famotidine) and of cytoprotective compounds are similar to that observed in younger patients. However, more data are necessary concerning the optimal dosage in relation to physiological age-related changes of liver and kidney function, the duration of prophylactic treatment, and importantly, the assurance of adequate patient compliance.

Histamine H2-receptor antagonists in peptic ulcer disease. Efficacy in healing peptic ulcers

Duodenal ulcer healing depends on the degree and length of inhibition of gastric secretion and upon the duration of therapy, while gastric ulcer healing is dependent mainly on the duration of therapy. Currently marketed doses of the histamine H2-receptor antagonists heal between 77 and 92% of duodenal ulcers at 4 weeks, and adjuvant treatment to eradicate Helicobacter pylori increases this rate. Once-daily administration is as effective as more frequent dosing regimens and may even result in higher healing rates. Gastric ulcers heal more slowly, but 75 to 88% of ulcers heal after 8 weeks of treatment. While newer more potent acid suppressors such as omeprazole heal ulcers slightly more quickly, the H2-receptor antagonists have an unparalleled safety record of over 15 years. It is unlikely that the prostaglandin analogues can improve on the efficacy of the H2-receptor antagonists with as low an incidence of side effects.