Learning Outcomes
By the end of this section, you should be able to:
- 31.2.1 Identify the characteristics of histamine-blocker and proton-pump inhibitor drugs used to treat GI disorders.
- 31.2.2 Explain the indications, action, adverse reactions, and interactions of histamine-blocker and proton-pump inhibitor drugs used to treat GI disorders.
- 31.2.3 Describe nursing implications of histamine-blocker and proton-pump inhibitor drugs used to treat GI disorders.
- 31.2.4 Explain the client education related to histamine-blocker and proton-pump inhibitor drugs used to treat GI disorders.
Histamine blockers, known as H2 blockers, and proton-pump inhibitors (PPIs) belong to the categories of drugs used to mitigate or hinder the production of stomach acid. These medications find widespread application in the treatment of conditions associated with heightened gastric acid secretion, encompassing gastroesophageal reflux disease (GERD), peptic ulcers, and heartburn.
Histamine Blockers
Histamine blockers, also called histamine H2-receptor antagonists or H2 blockers, have GI antisecretory action. By blocking the H2 receptors, drugs in this classification suppress gastric acid secretions and lower the hydrogen ion concentration of the gastric contents by attaching to the histamine (H2) receptor sites on gastric cells. Therefore, they prevent or treat heartburn, acid indigestion, gastric and duodenal ulcers, GERD, and hypersecretory conditions such as Zollinger-Ellison syndrome. H2 blockers are often used concurrently with antibiotics to treat H. pylori-associated peptic ulcer disease (PUD).
Link to Learning
Antisecretory Drug Therapy
This article from the Mayo Clinic helps with understanding antisecretory drug therapy and how it is beneficial in hypersecretory conditions such as Zollinger-Ellison syndrome.
Cimetidine
Cimetidine is an antisecretory medication used for short-term treatment of heartburn, erosive GERD, and gastric or duodenal ulcers. Prophylactic use of cimetidine includes prevention of stress ulcers or management of hypersecretory conditions such as Zollinger-Ellison syndrome. Cimetidine has a high selectivity for the H2 receptors on the parietal cells of the stomach. (Pino & Azer, 2023) Occupying these receptor sites inhibits all phases of basal (daytime and nocturnal) gastric acid secretion. By blocking the parietal cells, gastric acid production is reduced, raising the pH of gastric contents. This results in an indirect reduction of pepsin secretion. See drug prototype Table 31.4 for additional drug information.
Famotidine
Famotidine, a histamine inhibitor, is commonly used to treat heartburn, GERD, PUD, and hypersecretory conditions. Famotidine reduces the output of hydrochloric acid from the parietal cells, which in turn reduces the erosive damage to the gastric mucosa that may occur from hyperacidity. Famotidine is an effective prophylactic drug for stress ulcers and perioperative aspiration pneumonia. It is available orally and intravenously. See drug emphasis Table 31.3 for dosing information.
Nizatidine
Nizatidine blocks histamine at the H2 receptors of the parietal cells, significantly reducing the secretion of nocturnal gastric acid for up to 12 hours. It is an effective drug for GERD, gastric ulcers, and duodenal ulcers. Nizatidine may also be used for prevention of stress ulcers or the abolition of H. pylori. The medication is generally given twice per day for up to 8 weeks. If nizatidine is ordered daily, it is generally given at bedtime. See drug emphasis Table 31.3 for dosing information.
Table 31.3 lists common histamine blockers and typical routes and dosing for adult clients.
| Drug | Routes and Dosage Ranges |
|---|---|
| Cimetidine (Tagamet HB) |
For GERD: 400 mg orally 4 times daily or 800 mg orally twice daily for up to 12 weeks. For heartburn/dyspepsia: 200 mg orally 2–4 times daily. Reduce daily dosage by 50% if the client’s CrCl (creatinine clearance) is less than 30 mL/hour. Intermittent intravenous infusion: 300 mg every 6–8 hours infused over 15–20 minutes. Continuous intravenous infusion: 37.5 mg/hour (900 mg/day). |
| Famotidine (Pepcid) |
For GERD/gastritis: 20 mg orally twice daily for up to 8 weeks. For heartburn/dyspepsia: 20 mg orally 10–60 minutes before meals. For hypersecretory conditions: 20 mg orally every 6 hours or 20 mg intravenously every 12 hours. |
| Nizatidine (Axid) |
For GERD/gastritis: 150 mg orally twice daily for up to 12 weeks. For gastric/duodenal ulcers: 150 mg orally twice daily or 300 mg orally at bedtime for up to 8 weeks. |
Adverse Effects and Contraindications
Typical adverse effects of histamine blockers include diarrhea, headaches, mental confusion, agitation, depression, gynecomastia, neutropenia, agranulocytosis, increases in serum transaminase, arthralgia, rash, and alopecia. In rare cases, bradycardia, tachycardia, and AV heart block have been reported. Contraindications include hypersensitivity to the drug or any of its components.
Table 31.4 is a drug prototype table for histamine blockers featuring cimetidine. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.
| Drug Class H2-receptor antagonists/blockers Mechanism of Action Blocks H2 receptors, thereby suppressing gastric acid secretion, and lowers the hydrogen ion concentration in the stomach |
Drug Dosage For GERD: 400 mg orally 4 times daily or 800 mg orally twice daily for up to 12 weeks. For heartburn/dyspepsia: 200 mg orally 2–4 times daily. Reduce daily dosage by 50% if the client’s CrCl is less than 30 mL/hour. Intermittent intravenous infusion: 300 mg every 6–8 hours infused over 15–20 minutes. Continuous intravenous infusion: 37.5 mg/hour (900 mg/day). |
| Indications Short-term treatment of active duodenal and active benign gastric ulcers, erosive GERD, and hypersecretory conditions Therapeutic Effects Decreases gastric acids to provide symptomatic relief of hyperacidic GI conditions |
Drug Interactions Warfarin Phenytoin Theophylline Metronidazole Ketoconazole Food Interactions No significant interactions |
| Adverse Effects Diarrhea Headaches Dizziness Confusion Agranulocytosis Gynecomastia |
Contraindications Hypersensitivity Caution: Rare instances of cardiac arrhythmias and hypotension have been reported following the rapid administration of cimetidine hydrochloride injection by intravenous bolus |
Case Study
Read the following clinical scenario to answer the questions that follow.
Logan Gomez is a 35-year-old parent of two presenting to the health care provider with reports of burning in the upper part of the abdomen. The pain develops after eating. Often the pain wakes them from sleeping. Logan schedules an appointment with the provider.
| Vital Signs | Physical Examination | |
|---|---|---|
| Temperature: | 98.4° F |
|
| Blood pressure: | 118/66 mm Hg | |
| Heart rate: | 88 beats/min | |
| Respiratory rate: | 16 breaths/min | |
| Oxygen saturation: | 97% on room air | |
| Height: | 5'8" | |
| Weight: | 145 lb | |
Proton Pump Inhibitors
Proton pump inhibitors (PPIs) are antisecretory drugs that block both basal and stimulated gastric acid production. Gastric acid secretions are reduced by irreversibly blocking gastric hydrogen and potassium ATPase, an enzyme that produces gastric acid. Short-term use of PPIs for 4–6 weeks is an effective treatment for gastric and duodenal ulcers, GERD, and erosive esophagitis. The long-term use of PPIs is useful in hypersecretory conditions such as Zollinger-Ellison syndrome. Prophylactic use of PPIs is administered for clients at risk for stress ulcers, such as trauma clients on mechanical ventilation.
Omeprazole
Omeprazole is the prototype antisecretory PPI that suppresses the secretion of gastric acid by inhibiting the gastric proton pump found within the parietal cells. Various chemicals such as acetylcholine, histamine, and gastrin bind to receptors on parietal cells, prompting activation of hydrogen (H+), potassium (K+), and ATPase enzymes (the proton pump) that produces gastric acid secretion. Suppressing this action relieves GI distress to allow for healing of the mucosal lining.
Omeprazole is commonly used for dyspepsia (occurring at least twice per week), GERD, duodenal and gastric ulcers, erosive esophagitis, and prophylactically to prevent gastric ulcers related to the use of nonsteroidal antiinflammatory drugs (NSAIDs). Typical treatment is 4–8 weeks, along with diet and lifestyle modifications. Short-term use in combination with clarithromycin may be used to treat duodenal ulcers associated with H. pylori infections.
Omeprazole is available for oral use as a capsule, delayed-release tablet, and powder for oral suspension. Oral capsules and delayed-released tablets are best administered 30–60 minutes before breakfast. These must be swallowed whole and should not be opened, chewed, or crushed. It may take several days for omeprazole to take effect. In these cases, occasionally omeprazole is administered along with antacids until the omeprazole takes effect. Oral-suspension omeprazole may be administered via a gastrostomy tube. The omeprazole suspension contains granules that must be diluted in water. See drug prototype Table 31.7 for additional information.
Pantoprazole
Pantoprazole is a PPI used short-term for GERD and to manage or prevent erosive esophagitis. It is also useful in managing hypersecretory diseases, peptic ulcer disease, duodenal ulcers, dyspepsia, heartburn, and for stress ulcer prophylaxis. Pantoprazole suppresses gastric acid production by inhibiting the proton pump in the parietal cells.
Pantoprazole is available in delayed-release tablets, granules to create an oral suspension, and as a reconstituted solution for parenteral use. Tablets should be taken whole with or without food, without chewing, crushing, or breaking them. Granules may be administered orally or via a gastric tube. Oral suspension and granules may only be administered in apple juice or applesauce; the medication should not be mixed with water or other liquids or foods (Pfizer, 2023). However, the nurse should recommend that clients take small sips of water after administration to ensure the granules are washed down into the stomach. Pantoprazole is typically not used for longer than 8 weeks, especially in older clients. See drug emphasis Table 31.6 for dosing.
Esomeprazole
Esomeprazole is a weak base isomer of omeprazole that is converted to its active form in a highly acidic gastric environment. It inhibits the proton pump in parietal cells, significantly decreasing basal and stimulated gastric acid secretions.
Esomeprazole is an effective PPI that supports healing of erosive esophagitis, treatment of heartburn, prevention of recurrent gastric or duodenal ulcers, and ulcer prophylaxis with NSAID use. Additionally, esomeprazole is effective in the management of GERD, ulcers, and hypersecretory disease such as Zollinger-Ellison syndrome.
Esomeprazole is available in capsules, oral suspension, and powder for reconstitution for injection. The drug is destroyed in acidic environments; therefore, esomeprazole capsules are produced to allow for delayed absorption in the small intestine. Capsules must be swallowed whole and cannot be crushed or chewed. If a client cannot swallow capsules, the capsule may be opened and the capsule pellets mixed in applesauce The nurse should emphasize that the applesauce, once mixed, must be swallowed promptly without chewing the pellets to ensure the medication remains effective. Direct parenteral administration of esomeprazole must be reconstituted. See drug emphasis Table 31.6 for dosing.
Lansoprazole
Lansoprazole is a PPI that suppresses gastric acid formation, making it effective for short-term use to treat duodenal ulcers, erosive esophagitis, and GERD and as maintenance treatment for hypersecretory disorders. Lansoprazole is rapidly absorbed from the GI tract after leaving the stomach. The onset to reduce acid is approximately 2 hours. Ulcer symptom relief is generally acquired within the first week of its use. Lansoprazole is available as a sustained-release capsule and oral disintegrating tablets. See drug emphasis Table 31.6 for dosing.
Table 31.6 lists common PPIs and typical routes and dosing for adult clients.
| Drug | Routes and Dosage Ranges |
|---|---|
| Omeprazole (Prilosec) |
20 mg (delayed-release or disintegrating tablet) orally once daily for 14 days. |
| Pantoprazole (Protonix) |
40 mg orally once daily for 4–8 weeks or 40 mg intravenously once daily for 7–10 days. |
| Esomeprazole (Nexium) |
20 mg orally or 20–40 mg intravenously once daily for 4–8 weeks. |
| Lansoprazole (Prevacid) |
15 mg orally once daily 30 minutes before a meal for 14 days. |
Adverse Effects and Contraindications
Typical adverse effects include headache, dizziness, nausea, vomiting, abdominal pain, diarrhea, and cough. Contraindications of PPIs include hypersensitivity to PPIs and the drug rilpivirine, an HIV medication.
Table 31.7 is a drug prototype table for PPIs featuring omeprazole. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.
| Drug Class Proton pump inhibitor (PPI); antisecretory Mechanism of Action Suppresses gastric acid secretion by inhibiting the H+, K+, ATPase enzyme system (proton pump) |
Drug Dosage 20 mg (delayed-release or disintegrating tablet) orally once daily for 14 days. |
| Indications Short-term treatment of peptic ulcer, duodenal, and gastric ulcer diseases H. pylori infection GERD Erosive esophagitis Hypersecretion conditions Uncomplicated heartburn Therapeutic Effects An antiulcer agent that suppresses gastric acid secretion to relieve and promote ulcer healing |
Drug Interactions Amoxicillin Clarithromycin Diazepam Proguanil Moclobemide Phenytoin Warfarin Food Interactions No significant food interactions |
| Adverse Effects Diarrhea Abdominal pain Headache Nausea/vomiting Cough Back pain Dizziness |
Contraindications Hypersensitivity Rilpivirine |
Clinical Tip
Assess for Worsening GI Symptoms
When assessing a client’s response to medications for hyperacidity and antiulcer treatment, monitor signs and symptoms of GI distress—weight, bowel habits, nausea, vomiting, abdominal pain, bloating, or belching. Follow provider instruction on dietary intake; some GI conditions require increased fiber and fluids, while others may require “bowel rest” that involves smaller meals with soft foods.
Nursing Implications
The nurse should do the following for clients who are taking histamine blockers and proton pump inhibitors:
- Prior to administering, assess the client’s medical history, current drug list, and allergies.
- Educate the client regarding duration of use for these medications being short term, typically 4–8 weeks.
- Teach the client to avoid trigger foods that increase stomach acidity such as spicy foods, fried foods, and caffeine.
- Monitor for respiratory infection and/or pneumonia with PPI administration as these may lead to an overgrowth of bacteria in the upper GI tract that can migrate to the lungs.
- Provide the client with teaching regarding the drug and when to call the health care provider. See below for additional client teaching guidelines.
Client Teaching Guidelines
The client taking a histamine blocker and proton pump inhibitor should:
- Adhere to dosing regimen as prescribed by the health care provider, typically short-term administration of 4–8 weeks.
- Avoid trigger foods such as fast food, fried foods, spicy foods, caffeine, tea, and colas as these may increase stomach acid.
- Reports effects such as cough, fever, and shortness of breath to the health care provider as these may be symptoms of a severe adverse reaction.
The client taking a histamine blocker and proton pump inhibitor should not:
- Use for longer than prescribed.