Clinical efficacy of sucralfate in the treatment of gastric ulcer

Sucralfate causes malabsorption of L-thyroxine

PURPOSE

To determine if sucralfate causes malabsorption of L-thyroxine.

PATIENTS AND METHODS

Five healthy volunteers ingested L-thyroxine, 1,000 micrograms, administered orally (1) without sucralfate, (2) with sucralfate, 1 g, and (3) 8 hours after sucralfate, 2 g. The amount of L-thyroxine absorbed was calculated from the peak increase in serum T4 levels within 6 hours of hormone ingestion multiplied by the volume of distribution for the hormone.

RESULTS

Peak absorption of L-thyroxine in the absence of sucralfate was 796 micrograms (95% confidence interval (CI): 515-1,074 micrograms). Coadministration of sucralfate, 1 g, with L-thyroxine reduced thyroid hormone absorption to 225 micrograms (95% CI: 151-299 micrograms) (P = 0.0029 compared with control). Peak hormone absorption was delayed 2 hours by simultaneous sucralfate ingestion. Separation of administered L-thyroxine and sucralfate doses by 8 hours returned hormone absorption to control values. Maximum T3 levels did not differ, regardless of drug regimen, but suppression of thyroid-stimulating hormone (TSH) by L-thyroxine was reduced by coadministration of sucralfate.

CONCLUSIONS

Sucralfate causes malabsorption of L-thyroxine, presumably by intraluminal binding of hormone.

Activation of arachidonoyl phospholipase A2 in prostaglandin-mediated action of sucralfate

1. The mechanism of sucralfate-induced gastric mucosal prostaglandin generation was investigated using mucosal cells labeled with [14C]choline and [3H]arachidonic acid. 2. In comparison to the controls, the cells maintained in the presence of sucralfate showed a concentration dependent increase in lysophosphatidylcholine (LPC) synthesis and PGE2 generation. The maximal effect was attained at 25 microM sucralfate giving a 45.7% increase in LPC and 70% increase in PGE2. 3. Pretreatment with indomethacin prior to sucralfate, while causing inhibition in PGE2 generation, had no effect on LPC production and led to accumulation of free arachidonic acid. In the case of pretreatment with NDGA, the sucralfate caused increased LPC synthesis accompanied by enhanced PGE2 generation without free arachidonic acid accumulation. 4. The stimulatory effect of sucralfate on LPC synthesis and PGE2 generation was inhibited by phospholipase A2 inhibitors, mepacrine and BPB. The inhibitory effect was concentration dependent and attained maximum at 40 microM for BPB and 80 microM for mepacrine. 5. The results for the first time demonstrate that the enhancement in gastric mucosal prostaglandin generation by sucralfate results from the stimulation of mucosal phospholipase A2 for arachidonic acid release.

An examination of the alcohol consumption and peptic ulcer association--results of a national survey

Excessive alcohol consumption causes damages to the stomach or duodenum by impairing the integrity of the mucosal barrier. The aim of this study was to estimate the association between alcohol consumption and peptic ulcer, utilizing a large representative sample of the U.S. population, while controlling for cigarette smoking and major sociodemographic variables. Results indicated that alcohol consumption only minimally increased the odds of peptic ulcer. Thus, this study offers little support for the association between ethanol intake and peptic ulcer.

Effect of sucralfate on gastric mucosal calcium channels activity

1. The effect of anti-ulcer agent, sucralfate, on the activity of the gastric mucosal calcium channel was investigated using calcium channels purified from rat gastric epithelial cell membranes. 2. The channels on reconstitution into phosphatidylcholine vesicles responded in a concentration-dependent manner to a calcium channel activator, BAY K8644, as well as to a calcium channel antagonist, PN200-110. The 45Ca2+ uptake was inhibited by sucralfate. Maximum inhibitory effect was attained at 100 micrograms/ml sucralfate, at which point a 52% decrease in the uptake occurred. 3. EGF-induced channel protein phosphorylation showed an increase in tyrosine phosphorylation of 55 and 170 kDa proteins, and the vesicles containing the phosphorylated channels displayed a 48% greater 45Ca2+ uptake. This phosphorylation process was inhibited by sucralfate. Furthermore, sucralfate also interfered with the binding of EGF to calcium channel protein. 4. The results indicate that sucralfate protects the cellular integrity from calcium imbalance by modulating the EGF-stimulated gastric mucosal calcium channel phosphorylation.

Enhancement of gastric mucosal epidermal growth factor and platelet-derived growth factor receptor expression by sucralfate

1. The effect of an anti-ulcer agent, sucralfate, on the expression of gastric mucosal epidermal growth factor (EGF) and platelet derived growth factor (PDGF) receptors was investigated. 2. Gastric mucosal cell membranes, isolated from the stomach of groups of rats, one receiving twice daily for 3 consecutive days a dose of 100 mg/kg sucralfate, and the other only the vehicle, were used as source for EGF and PDGF receptors. 3. Binding assays revealed the presence of both types of receptors, activation of which led to the elevation of tyrosine kinase activity as evidenced by a marked increase in membrane protein tyrosine phosphorylation patterns. 4. The specific receptor binding in the control group was 2.46 fmol/mg protein for EGF and 1.46 fmol/mg protein for PDGF, whereas the respective binding values in the sucralfate treated group increased by 61 and 65%. 5. The results suggest that sucralfate is capable of enhancement of epithelial proliferative activities through the stimulation of gastric mucosal EGF and PDGF receptors.