Effect of roxatidine acetate on daytime and night-time peptone-stimulated gastric acid secretion

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

Roxatidine acetate is a histamine H2-receptor antagonist which, after almost complete oral absorption (greater than 95%), is rapidly converted to its active metabolite, roxatidine, by esterases in the small intestine, plasma and liver. Roxatidine is a potent inhibitor of basal and stimulated gastric acid secretion in animals and humans and, like most other H2-receptor antagonists, has no anti-androgenic effects and does not interfere with the hepatic metabolism of other drugs. Large-scale trials have shown that roxatidine acetate 150mg per day is as effective as standard doses of cimetidine and ranitidine in the treatment of patients with duodenal or gastric ulcer, and that roxatidine acetate 75mg in the evening is likely to become a 'standard' regimen for the prevention of peptic ulcer recurrence. Preliminary data also suggest that roxatidine acetate may be useful in the treatment of reflux oesophagitis and stomal ulcer, and in the prevention of pulmonary acid aspiration. Roxatidine acetate is an H2-receptor antagonist which has been well tolerated in clinical trials. However, broader experience is required before definitive statements about tolerability relative to other H2-receptor antagonists can be made, and before the role of roxatidine acetate in the treatment of reflux oesophagitis and stomal ulcer, and the prophylaxis of acid aspiration pneumonitis, can be clearly defined.

The pharmacodynamics and pharmacokinetics of multiple doses of the new H2-receptor antagonist, roxatidine acetate, in healthy men

Roxatidine acetate (HOE 760, TZU 0460) is a new H2-receptor antagonist which is more potent than cimetidine and ranitidine. A randomised, double-blind, placebo-controlled study was conducted in healthy men to determine the effects of multiple oral doses of roxatidine acetate on unstimulated gastric acid secretion, and to assess the preliminary multiple-dose pharmacokinetics of its active desacetyl metabolite. The subjects were randomised to receive either roxatidine acetate 150 mg or placebo daily at 9 pm for 14 days. Gastric secretions were collected by aspiration using a nasogastric tube placed in the distal part of the stomach. Gastric fluid volume, pH, and acid concentrations were determined for 2 hours before drug administration and over 24 hours after administration on days 1, 7, 14 (the last day of dosing), and 17 (3 days after the last dose). Plasma and urine samples were collected throughout the study for the pharmacokinetic assessment. All subjects completed the study without side effects or clinically significant changes in any of the safety variables. Subjects receiving roxatidine acetate had substantial increases in gastric pH and decreases in acid secretion compared to baseline and to placebo-treated subjects. The duration of effect was approximately 12 hours. Nocturnal pH was greater than or equal to 6.0 in 80% of the roxatidine acetate-treated subjects. When sampled 3 days after the last dose (day 17) no differences in pH, acid secretion, or gastric volume were observed between the roxatidine acetate- and placebo-treated groups. The gastric pH increased with the mean plasma concentrations of the desacetyl metabolite. Mean plasma levels at steady state were attained between the 4th and 7th days after which there was no evidence of appreciable accumulation of the desacetyl metabolite. Roxatidine acetate 150 mg administered orally at 9 pm for 14 days to healthy men was safe, well tolerated, and produced clinically relevant increases in gastric pH, and decreases in gastric acid concentration, without affecting gastric fluid volume.