Singapore Drugs Database

Indication

Indicated for healing all grades of erosive esophagitis (EE), maintaining and healing of EE and relief of heartburn, and treating heartburn associated with symptomatic non-erosive gastroesophageal reflux disease (GERD).

Mechanism of Action

H/K ATPase is involved in the secretion of hydrochloric acid, hydrolyzing ATP and exchanging H+ ions from the cytoplasm for K+ ions in the secretory canaliculus, which results in HCl secretion into the gastric lumen. Dexlansoprazole inhibits this effect of H/K ATPase by demonstrating a high degree of activation in the acidic environment. After passing through the liver and reaching the gastric parietal cells activated by a meal, PPIs undergo protonation in the acidic pH environment, followed by conversion to sulphenamide which represents the active form of the drug. Sulphenamide inhibits the activity of the proton pump and hence the transport of hydrogen ions into the gastric lumen via covalent binding to the SH groups of the cysteine residues of H/K ATPase [A19567].

Pharmacokinetics

Absorption

After oral administration, the peak plasma concentration increases approximately dose proportionally. The dual delayed release formulation achieves two plasma concentration peaks, where the first peak occurs one to two hours after administration, followed by a second peak within four to five hours. The median time (Tmax) to peak plasma concentrations (Cmax) of 30 mg dexlansoprazole SoluTab tablet was 4 hours and ranged from 1 to 6 hours with the Cmax value of 688 ng/mL.

Distribution

The apparent volume of distribution after multiple doses in symptomatic GERD patients was 40 L.

Metabolism

Dexlansoprazole is extensively metabolized in the liver by oxidation, reduction, and subsequent formation of sulfate, glucuronide and glutathione conjugates to inactive metabolites. Oxidative metabolites are formed by the cytochrome P450 (CYP) enzyme system including hydroxylation mainly by CYP2C19, and oxidation to the sulfone by CYP3A4. Dexlansoprazole is the major circulating component in plasma regardless of CYP2C19 metabolizer status. In CYP2C19 intermediate and extensive metabolizers, the major plasma metabolites are 5-hydroxy dexlansoprazole and its glucuronide conjugate, while in CYP2C19 poor metabolizers dexlansoprazole sulfone is the major plasma metabolite.

Elimination

Clearance

Apparent clearance (CL/F) in healthy subjects was 11.4 to 11.6 L/hour, respectively, after five days of 30 or 60 mg once daily administration.

Toxicity

Oral LD50 value in mice, rats and dogs is > 5,000 mg/kg. Most commonly reported adverse reactions are diarrhea, abdominal pain, nausea, upper respiratory tract infection, vomiting, and flatulence. There are no reports of significant overdose but serious adverse events of hypertension have been reported in association with twice daily doses of DEXILANT 60 mg. Nonclicnial toxicology of dexlansopraole was assessed using lansoprazole studies. In two 24-month carcinogenicity studies involving rats, lansoprazole induced dose-related gastric ECL cell hyperplasia and ECL cell carcinoids and increased the incidence of intestinal metaplasia of the gastric epithelium in both sexes of rats. Dexlansoprazole is expected to have no effect on fertility and the reproductive system.

Active Ingredient/Synonyms

2-((R)-((3-methyl-4-(2,2,2-trifluoroethoxy)-2-pyridinyl)methyl)sulfinyl)-1H-benzimidazole | Dexlansoprazole |