Pharmacist Approach to Heartburn, continued. Figure 6 Lifestyle Modifications for Heartburn 5 meals, raising the head of the bed, and avoiding recumbence for 2–3 hours after meals). The pharmacist may indicate to the patient the benefit of pharmacological treatment options from 3 general classes of medicines, Antacids and Alginates, H2RA Receptor Blockers (H2RA) and Proton Pump Inhibitors (PPI) (see Figure 9 at end). Antacids and alginates. Antacids provide rapid, albeit, temporary relief of mild short-term or infrequent heartburn. Antacids are salt compounds of aluminum, magnesium and/or calcium. Viscous alginates, generally provided in combination with an antacid, create a protective barrier on top of gastric contents. Magnesium-containing antacids should be avoided in patients with impaired renal function. If antacids are needed for >2 days a week, the patient may require an OTC H2RA or PPI. Antacids may provide neutralizing and protective effects depending upon their ingredients. Antacids appear to primarily exert their action in the esophageal lumen. Figure 7 Selected medicine interactions with Antacids 5 Antacids are capable of interacting with a wide variety of drugs through three primary mechanisms: 1) Binding of another drug in the intestinal tract, 2) Changes in GI pH, and 3) Changes in urinary pH. To prevent the most common and potentially detrimental interactions, patients should not use antacids within 2 hours of enteric-coated products or any of the drugs listed in Figure 7. Antacid-induced alkalinization of the urine may increase blood concentrations of amphetamines and quinidine and decrease concentrations of salicylates. Antacids and alginates are preferred in pregnancy; OTC H2RAs are comparable but not superior to antacids for episodic heartburn and GERD. H2RAs. Histamine H2-receptor antagonists work as selective antagonists at the histamine H2-receptor, which is located on the basolateral aspect of the parietal cell. The H2RAs suppress acid production by parietal cells—but to a much lesser degree than the PPIs. Even during treatment with an H2RA, acid production by the parietal cells can be stimulated by the ingestion of food. Since much reflux (and, therefore, heartburn) occurs in the few hours after meals, this helps to explain why PPIs have proven to be more effective for managing heartburn than the H2RAs. OTC H2RAs (cimetidine, famotidine, nizatidine, ranitidine) are effective for the treatment of mild-to-moderate infrequent heartburn. The lower OTC dosages should be used for mild symptoms, whereas the higher dosages are used for patients with moderate symptoms. The onset of symptom relief is 30–45 minutes, and their effects last ≤10 hours. H2RAs should be taken on a “when-needed” basis, as tolerance (tachyphylaxis) may develop to their anti-secretory effect if they are taken every day. An H2RA may be taken 30–60 minutes prior to eating or exercise to prevent anticipated symptoms. H2RAs are well-tolerated and have a low incidence of side effects such as headache, diarrhea and constipation. H2RAs have advantages (some of which are particularly important for patients in developing countries): faster onset of action, no need to time administration before meals, lower cost, no fear of interaction with clopidogrel, probably safer in pregnancy. Furthermore, they can be used in patients who cannot tolerate PPIs because of side effects.7 The interaction that occurs with theophylline and warfarin when the cytochrome P-450 enzyme system is inhibited by cimetidine and ranitidine requires monitoring.8 Evidence, to date, indicates that famotidine does not bind to cytochrome P-450 to a significant extent. Proton Pump Inhibitors (H+/K+ ATPase Inhibitors). The effects of PPIs can last up to 24 hours. Standard dose, once-daily PPI is more efficacious than an H2RA. Therapy may be continued for 2-8 weeks, whereupon treatment can be stopped; therapy can be restarted if symptoms recur. There are no clinically important differences among standard doses of PPIs. PPIs are usually well-tolerated with few short-term side effects. Some concerns have arisen regarding an association with some long-term adverse events9 (Figure 8). When PPIs are strongly indicated, their benefits far outweigh their theoretical risks. However, in cases where PPIs do not have a clear ongoing indication, it is prudent to World Digestive Health Day WDHD May 29, 2015 WGO HANDBOOK HEARTBURN: A GLOBAL PERSPECTIVE 27
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