Aciphex
The effects of rabeprazole on parietal cells and enterochromaffin-like cells in rats: a comparison with omeprazole.

Tari A, Kawano M, Kodama K, Yonei Y, Okahara S, Haruma K, Sumii K, Kajiyama G.

Department of Internal Medicine, Hiroshima Red Cross Hospital and Atomic Bomb Survivors Hospital, Hiroshima, Japan.

BACKGROUND: We investigated the effects of rabeprazole compared with those of omeprazole on enterochromaffin-like cells and parietal cells in rats. METHODS: Rabeprazole or omeprazole was administered for 7 days by intraperitoneal injection (100 mg/kg or 20mg/kg once a day) and the serum gastrin concentration, the antral density of G cells and D cells, fundic histamine content, fundic H+, K+-ATPase mRNA level, and parietal cell morphology were determined. RESULTS: Both rabeprazole and omeprazole inhibited gastric acid secretion and increased the intragastric pH to over 6.5, as well as causing a marked increase in the serum gastrin concentration. The serum gastrin level was lower with rabeprazole treatment than with omeprazole treatment at both doses. Also, the antral G-cell density was higher with omeprazole than with rabeprazole, while the increase in both the histamine content and the H+, K-ATPase mRNA level in the fundic mucosa was higher with omeprazole treatment at both doses, with the difference being significant at 100 mg/kg. Ultrastructural examination indicated that the stimulation of parietal cells by omeprazole was stronger than that by rabeprazole. CONCLUSIONS: Rabeprazole treatment does not drive enterochromaffin-like cells and parietal cells as strongly as omeprazole treatment despite its potent acid suppressive effect, suggesting that it represents a new generation of proton pump inhibitors.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11931530&dopt=Abstract rabeprazole Aciphex



Aciphex
Impact of proton pump inhibitor utilization patterns on gastroesophageal reflux disease-related costs.

Hall J, Dodd S, Durkin M, Sloan S.

OBJECTIVE: To determine proton pump inhibitor (PPI) treatment patterns and their effect on costs related to gastroesophageal reflux disease. METHODS: This study used claims data to identify continuously enrolled subjects diagnosed with gastroesophageal reflux disease (GERD) and newly treated with a PPI between Oct. 1, 1999 and March 31, 2000. Data were analyzed for 6 months following PPI initiation. Results were stratified by first PPI filled during the study period. Compliance (as measured by a medication-possession ratio), dosage escalation (> 25 percent of initial dose), and daily average consumption (DACON) were measured. Regression analysis was performed on GERD-related costs using treatment patterns, type of PPI drug, and compliance as independent variables of interest. RESULTS: Of 75,452 subjects, there were 51,232 (67.9 percent) lansoprazole, 22,829 (30.3 percent) omeprazole, and 1,391 (1.8 percent) rabeprazole subjects. The possession ratio was not significantly different by drug. Only 3.5 percent of rabeprazole subjects escalated versus 5.5 percent of omeprazole subjects and 9.3 percent of lansoprazole subjects (p = .0001). Among subjects with esophageal ulcer or hiatal hernia, rabeprazole users had a significantly lower final DACON (1.03) versus both lansoprazole (1.20) and omeprazole subjects (1.22, p = .0299). Subjects who were compliant with therapy (ratio > 0.80) had 43 percent higher GERD-related pharmacy costs and 33 percent higher GERD-related total costs (both p < .001). GERD-related medical costs were not significantly affected by compliance. Subjects who filled lansoprazole prescriptions had 9.4 percent higher GERD-related pharmacy costs versus rabeprazole subjects (p < .01). Omeprazole subjects had 12.5 percent higher GERD-related total costs versus rabeprazole subjects (p < .01), while lansoprazole subjects had 18 percent higher GERD-related total costs versus rabeprazole subjects (p < .001). CONCLUSIONS: Rabeprazole subjects had lower GERD-related costs, less escalation, and lower DACON (measured as number of tablets consumed per day), compared to lansoprazole and omeprazole subjects. Compliance was not significantly different between the drugs, nor did increased compliance decrease GERD-related costs.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12181872&dopt=Abstract rabeprazole Aciphex



Aciphex
Effects of rabeprazole, lansoprazole and omeprazole on intragastric pH in CYP2C19 extensive metabolizers.

Saitoh T, Fukushima Y, Otsuka H, Hirakawa J, Mori H, Asano T, Ishikawa T, Katsube T, Ogawa K, Ohkawa S.

Department of Internal Medicine, Tokyo Women's Medical University, Daini Hospital, Japan. ssumiko fa2.so-net.ne.jp

AIM: To investigate the inhibitory effects on gastric acid secretion of three proton pump inhibitors, omeprazole, lansoprazole and rabeprazole, using a three-way crossover design in healthy Helicobacter pylori-negative,S-mephenytoin 4'-hydroxylase (CYP2C19) homo- and hetero-extensive metabolizers. METHODS: Eight healthy Japanese male volunteers were enrolled. After the administration of rabeprazole (10 mg/day), lansoprazole (30 mg/day) or omeprazole (20 mg/day), intragastric pH monitoring was commenced from 24 h before the first proton pump inhibitor dose, and continued for days 1-3 after proton pump inhibitor administration. The pH electrode was used for 48 h and changed just before pH monitoring on day 2. RESULTS: For the administration of 10 mg/day rabeprazole, the mean ratios of the 24-h pH > or = 3 holding time were 5.7 +/- 1.1%,13.6 +/- 2.2%, 35.3 +/- 2.7% and 62.8 +/- 3.1% for the pre-treatment day and days 1, 2 and 3, respectively. The same ratios for lansoprazole (30 mg/day) were 5.7 +/- 0.7%, 7.4 +/- 1.5%, 13.6 +/- 3.4% and 26.6 +/- 4.9%; the same ratios for 20 mg/day omeprazole were 5.9 +/- 0.9%, 6.1 +/- 1.2%, 11.4 +/- 2.8% and 16.4 +/- 4.6%. The mean ratio of the 24-h pH > or = 3 holding time of days 1-3 increased significantly compared to the pre-treatment day (P < 0.01) with the administration of rabeprazole and lansoprazole. The magnitude of inhibition of gastric acid secretion after rabeprazole administration was stronger than that after lansoprazole. A significant elevation of the mean ratio of the 24-h pH > or = 3 holding time was demonstrated on days 2 and 3 with omeprazole (P < 0.01). CONCLUSIONS: In H. pylori-negative CYP2C19 extensive metabolizers, rabeprazole (10 mg/day) shows a faster onset of rising intragastric pH and a stronger inhibition of gastric acid secretion than do lansoprazole (30 mg/day) or omeprazole (20 mg/day).

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12269976&dopt=Abstract rabeprazole Aciphex