Smoking and pH response to H2-receptor antagonists

Effects of smoking and nicotine on the gastric mucosa: a review of clinical and experimental evidence

Epidemiological and experimental evidence have shown that nicotine has harmful effects on the gastric mucosa. The mechanisms by which cigarette smoking or nicotine adversely affect the gastric mucosa have not been fully elucidated. In this report, clinical and experimental data are reviewed. The effects of nicotine from smoking on gastric aggressive or defensive factors are discussed. Nicotine potentiates gastric aggressive factors and attenuates defensive factors; it also increases acid and pepsin secretions, gastric motility, duodenogastric reflux of bile salts, the risk of Helicobacter pylori infection, levels of free radicals, and platelet-activating factor, endothelin generation, and vasopressin secretion. Additionally, nicotine impairs the therapeutic effect of H2-receptor antagonists and decreases prostaglandin synthesis, gastric mucosal blood flow, mucus secretion, and epidermal growth factor secretion. Although many of the studies provide conflicting results, the bulk of the evidence supports the hypothesis that nicotine is harmful to the gastric mucosa.

Does smoking influence the pharmacokinetics and pharmacodynamics of the H2-receptor antagonist famotidine?

Twelve healthy habitual cigarette smokers and eight non-smokers participated in a double-blind placebo controlled study to determine the effect of smoking on the pharmacokinetics and pharmacodynamics of the H2-receptor antagonist famotidine. In smokers, cigarette smoking was standardised and started 1 h before (A), or 2 h after (B) drug administration, or was prohibited (C). Intragastric pH-levels (IGpH) were measured with an ambulatory pH-recorder. Famotidine (40 mg orally) significantly raised median 22 h IGpH in non-smokers and smokers in all study periods. The smoking sequence (A, B, C) did not significantly influence median 22 h IGpH in both placebo-treated and famotidine-treated smokers, and no significant difference in median 22 h IGpH was shown between smokers and non-smokers. Plasma drug concentrations were similar in the various experiments, although famotidine was detected earlier in plasma from non-smokers compared with smokers (P less than 0.05). Smoking did not interfere significantly with the pharmacokinetics and pharmacodynamics of famotidine.

Recent advances in the management of gastro-oesophageal reflux disease

The basis of treatment of reflux oesophagitis is change in behaviour and lifestyle. In the presence of mild symptoms antacids/alginate may be instituted. In case of Savary grade I and II oesophagitis at endoscopy, H2-receptor antagonists (H2RAs), alone or in combination with a prokinetic or mucosaprotective agent, are the first choice of treatment. Drug treatment should be continued for at least 8-12 weeks. In case of resistance to treatment or in case of severe and/or complicated reflux oesophagitis, omeprazole should be prescribed. Maintenance treatment is necessary in patients with severe reflux oesophagitis and in patients with quick relapses, once therapy has stopped. Full-dose H2RAs are required to prevent recurrences. In case of resistance to H2RAs, omeprazole should be used. Anti-reflux surgery should be considered in patients, especially at young age, who have an insufficient response to medical management, due either to lack of compliance or to therapeutic failure.