Pentagastrin-stimulated acid

The racemate and the two isomers (15 mg each, all as sodium salts) were given orally and in a random order to each of four healthy subjects, who were defined genetically as extensive metabolizers (Fig. 2.19a and b). Drug plasma concentrations and the inhibition of pentagastrin-stimulated acid secretion were monitored. 

Hammer RA, Ochoa A, Fernandez C, Ertan A, Arimura A (1992) Somatostatin as a mediator of the effect of neurotensin on pentagastrin-stimulated acid secretion in rats. Peptides 13 1175-1179... 

There is a sex-related difference in human gastric acid secretion. Healthy women secrete significantly less basal and pentagastrin-stimulated acid then men with a median 24h integrated acidity of 485 mmol h vs. 842mmol h / In a sample of 365 healthy subjects, the average basal pH was 2.16 0.09 for men and 2.79 0.18 in women. ... 

Omeprazole administered i.v. (0.5 mg/kg once daily) had a pronounced effect on basal acid output and gastric pH within 2h of administration, and basal and pentagastrin-stimulated acid output were significantly inhibited 24 h after the fourth consecutive dose (Jenkins et al 1992b). 

Omeprazole admmistered i.m. (0.25 and 1.0 mg/ kg) similarly inhibited basal and pentagastrin-stimulated acid output and increased gastric pH, with a greater response to the higher dose rate (Sandin et al 1999). Peak plasma levels of omeprazole were measured 20 min after administration and thereafter plasma levels rapidly declined (half-life of 45 to 60 min). Inhibition of acid secretion persisted for many hours after the plasma levels had declined to barely detectable. TTie bioavailability of the i.m. administered omeprazole was 75%. 

Inhibition of gastric acid secretion 50 mg, no effect on basal acid secretion 2.5,10, 50 mg p.o. inhibited pentagastrin-stimulated acid secretion (0.05-2 /Jtg kg- h" ) (227). 

Lind, X, Cedeberg, C., Ekenved, G., Haglund, U., Olbe, L. Effect of omeprazole - a gastric proton pump inhibitor - on pentagastrin stimulated acid secretion in man. Gut 1983, 24, 270-276. 

A2. Albinus, M., Reed, J. D., Gomez-Pan, A., and Schally, A. V., Comparison of the inhibition of histamine and pentagastrin stimulated acid secretion by growth hormone-release inhibiting hormone (Somatostatin). Submitted for publication. 

Figure 1. Inhibition of pentagastrin-stimulated acid secretion and plasma gastrin levels in female rats after daily achninistration of omeprazole (n = 5).

Corticosteroids induce hypergastrin-aemia, but pentagastrin-stimulated acid and pepsin output are not affected (116). Corticosteroids, in acute studies, did not influence ion fluxes across human gastric mucosa (62). 

On a weight basis 20 times more potent than cimetidine and 7.5 times more potent than ranitidine in inhibiting basal and pentagastrin stimulated gastric acid secretion. It is a competitive-noncompetitive inhibitor of receptors. It has a long-... 

Pharmacokinetics (PK) and effect on pentagastrin-stimulated peak acid output (PAO) of omeprazole (O) and its two optical isomers, S-omeprazole/esomeprazole (E) and R-omeprazole (R-O). Reproduced with permission from the American Gastroenterological Association. 

H2 receptor antagonists are extremely effective inhibitors of acid secretion during pentagastrin stimulation and are able to inhibit partially the secretion due to vagal stimulation. Since neither gastrin nor acetylcholine binds to H2 receptor, it is apparent that histamine must therefore operate on the pathway of stimulation initiated by these mediators. Thus it seems likely that histamine rather than gastrin is the final mediator of acid secretion. 

Black found that burimamide inhibits pentagastrin-stimulted as well as histamine-stimulated acid secretion, and he suggested that H2 blockade might resolve the long-debated question of whether histamine is the final common mediator of acid secretion. 

Chandler AM, Johnson LR. Pentagastrin-stimulated incorporation of " C-orotic acid into RNA of gastric and duodenal mucosa. Proc Soc Exp Biol Med 141 110-113, 1972. 

Far more intrinsic factor is secreted than is needed to bind and assimilate dietary cobalamin. Thus, in a 60-minute period, the stimulated human stomach secretes enough intrinsic factor to bind all cobalamin ingested in a 24-hour period. Intrinsic factor secretion appears to be stimulated by all agents that stimulate acid secretion. It is thus secreted under stimulation by histamine, pentagastrin, and cholinergic agents and is similarly inhibited by cimetidine. The pattern of intrinsic factor secretion, however, differs from that of acid secretion. Exposure to an agonist results in a rapid stimulation, with peak levels of intrinsic factor within 15 to 30 minutes, whereas acid increases over a far slower period. When acid secretion is at a maximum level, intrinsic factor secretion has returned to control levels. 

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