Pharmacy & Therapeutics - March 2009 - (Page 143) Administration of Proton Pump Inhibitors In Patients Requiring Enteral Nutrition Terri M. Wensel, PharmD Key words: proton pump inhibitor, enteral, administration further complicated by the fact that unless the PPI molecule is protected, it is subject to degradation in the presence of stomach acid.3 The PPIs (except for Zegerid) are therefore encapsulated or enterically coated to prevent premature activation of the drug in the presence of gastric acid.2,3 Opening the capsule and administering the contents have the potential to leave the granules vulnerable to degradation, premature activation, and decreased efficacy. Information about administering PPIs via enteral feeding tubes is limited. This article discusses the available literature and provides practitioners with suitable methods of administering PPIs via nasogastric, gastrostomy, and jejunostomy tubes. A search of PubMed utilizing the terms omeprazole, lansoprazole, esomeprazole, pantoprazole, rabeprazole, enteral, nasogastric, gastrostomy, and jejunal was conducted. All retrievable in vitro and in vivo studies describing an extemporaneous formulation administered via an enteral tube were included for review. INTRODUCTION Role of Proton Pump Inhibitors Patients requiring enteral nutrition may also be in need of acid-suppressing therapy with proton pump inhibitors (PPIs). Currently, five PPIs are available in the U.S.: omeprazole (Prilosec, AstraZeneca), omeprazole/sodium bicarbonate (Zegerid, Santarus), esomeprazole (Nexium, AstraZeneca), lansoprazole (Prevacid, Tap/Takeda), pantoprazole (Protonix, Wyeth), and rabeprazole (Aciphex, Eisai). All of these products are available in oral form, and several are also available in an intravenous (IV) form (Table 1).1 PPIs are highly ef fective for the treatment of gastro esophageal reflux disease (GERD), ulcers, and gastrointestinal (GI) bleeding. Indications approved by the FDA for each PPI are provided in Table 1. When gastric contents are at a pH of below 2, protein denaturation and the conversion of pepsinogen to pepsin occur and can lead to irritation of the esophagus.2 Other factors such as histamine and gastrin also play a role in the secretion of gastric acid with resulting esophageal irritation.3 Gastric contents at a pH of less than 4 for extended periods of time have been associated with a higher severity of disease. Therefore, it is not surprising that time spent at a pH above 4 has been correlated with esophageal healing.2 PPIs exhibit their effects by inhibiting H+/K+-adenosine triphosphatase (ATPase) in parietal cells.2,3 This inhibition sufficiently raises and maintains gastric pH to exceed 4.2 Currently available PPIs can maintain this pH level 50% to 60% of the time.2 NASOGASTRIC TUBES Many PPIs include instructions in the package insert for administration via nasogastric tubes.5–10 Table 2 presents enteral tube instructions for omeprazole delayed-release oral suspension packets, omeprazole/sodium bicarbonate powder for suspension, lansoprazole (Prevacid Solu-Tab), pantoprazole for delayed-release oral suspension, and esomeprazole delayed-release capsules and oral suspensions. Although the use of capsule contents is not documented in the package insert, they have been evaluated in various formulations for use via an enteral feeding tube. Available in both capsule and suspension forms, Zegerid contains an antacid component in addition to a PPI component. The capsules, however, should not be opened.8 If Zegerid is to be used, the powder for suspension should be prescribed. Several studies have sought to determine the bioavailability and efficacy of many of these formulations via the enteral route and have also compared them with capsule and IV formulations. When considering agents to include on an institutional formulary, P&T committee members may be influenced by a drug’s bioavailability and comparative efficacy. A review of the literature describing enteral administration is provided next. Table 3 includes instructions on compounding the formulations used in the following studies. Tube Feedings Patients who require enteral nutrition may be supported by one of the following insertion techniques: nasogastric tube, nasoduodenal tube, gastrostomy tube, jejunostomy tube, or a combined gastrojejunostomy tube.4 The use of feeding tubes to administer medications is common practice, but the procedure is complicated by the potential for the medication to clog or to adhere to the sides of the tube. Although several PPIs are available in an IV form (see Table 1), if a patient has a functional GI tract, it may still be feasible to administer an oral formulation. The use of IV PPIs may also be complicated by a lack of venous access and cost restrictions. Administration of the capsule’s contents via a feeding tube is Dr. Wensel is Assistant Professor at Samford University’s McWhorter School of Pharmacy, Global Drug Information Service, in Birmingham, Alabama. Accepted for publication October 16, 2008. Omeprazole Delayed-Release Capsules Larson et al.11 In one of the earliest studies of omeprazole given by nasogastric tube, the agent’s efficacy and bioavailability were simDisclosure. The author reports no commercial or financial relationships in regard to this article. Vol. 34 No. 3 • March 2009 • P&T® 143
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