GERD用药

If lifestyle modifications alone are unsuccessful in controlling reflux then medication will likely be the next step. Listed below (categorically in the order they are usually tried) are the different types of medication used to treat reflux or GERD, (where possible the generic name will be listed in brackets).

ANTACIDS

Simply put, these neutralize acid in the stomach. Antacids do not decrease acid production, rather work by temporarily neutralizing the acid that is in the stomach at the time they are taken. They work quickly but do not have long lasting effects.

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Anything with a high concentration of loose hydrogen ions is an acid. Stomach juice contains a large number of hydrogen ions and is therefore, an acid. Antacids, which usually contain aluminum or magnesium, are weak bases. Bases contain oxygen and hydrogen atoms that soak up loose hydrogen ions, converting them to water. Because water is neutral and antacids convert the acid to water we say they neutralize the acid. These drugs will affect only the acid that is in stomach at the time they are taken, as more acid is pumped into the stomach the effects begin to wear off.

Antacids containing magnesium can act as laxatives, whereas those containing aluminum may cause constipation.

Common antacids are:

* Maalox? (Aluminum Hydroxide and Magnesium Hydroxide)
* Mylanta? (Aluminum Hydroxide and Magnesium Hydroxide)
* Gaviscon? (Aluminum Hydroxide and Magnesium Carbonate)
* Milk of Magnesium? (Magnesium Hydroxide)


CYTOPROTECTIVE AGENTS

Carafate (Sulcralfate) & oral suspension - Helps protect the tissue of the esophagus by coating it with a thick, protective layer

Cytotec (Misoprostol) - Misoprostol is a synthetic prostaglandin. Prostaglandins are substances naturally found in the body. In the stomach they are believed to protect the inner stomach lining.

ACID BLOCKERS (H2 RECEPTOR ANTAGONIST)

Also called H2 Blockers, this class of drug works by blocking acid production.

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Histamine is a chemical produced by the body for many different purposes. It is one of the three pathways leading to acid production. When histamine (or H2) binds to H2-receptors found on cells in the stomach lining (parietal cells), it causes the cells to produce acid. This is a normal function of the body to aid in digestion. These drugs work to block the H2-receptors, stopping histamine from binding to them, ultimately reducing the amount of acid these cells create.

Listed below are commonly used acid blockers.

* Zantac?? (Ranitidine)
* Axid? (Nizatidine)
* Tagamet? (Cimetidine)
* Pepcid? (Famotidine)


Proton Pump Inhibitors or PPI's

PPI's are the most effective medication used to control reflux. They almost completely shut down the acid pumps in the stomach.

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The proton pump is the final stage in acid secretion so shutting down the proton pump provides the best defense in controlling acid by affecting not just the action of histamine but all three pathways of acid production. Proton Pump Inhibitors (PPI's) act by blocking the proton pump (hydrogen-potassium adenosine triphosphatase enzyme system-the K+/H+-ATPase) of the parietal cell. This almost completely stops acid production. Proton pump inhibitors are typically tried after histamine blockers have failed, as the cost can be more than double that of the histamine blockers. They are significantly more effective than H2 blockers and said to reduce gastric acid secretion by up to ninety-nine percent.

Because these types of meds are delayed-release, the manufacturers of these drugs recommend that they not be chewed or crushed. Omeprazole (Prilosec?) and lansoprazole (Prevacid?) are available as enteric-coated granules in capsules (referred to as "beads" or "pellets"). In addition, a new oral suspension formulation of lansoprazole was FDA-approved in January 2002.

Currently, the manufacturers of lansoprazole and esomeprazole include instructions on the administration of the granules in applesauce, water or acidic juices for oral administration. In addition, the package inserts for lansoprazole and esomeprazole state that the granules or pellets within the capsules may be administered down a gastric tube after mixing with an acidic juice or water. The marketed formulations of the PPIs limit their use to patients that can swallow. However, some of the PPIs can be made into a liquid, permitting their use for patients that cannot swallow, have difficulty swallowing, or have gastric feeding tubes. The following are preparations the pharmaceutical manufacturers suggested and have been evaluated for effectiveness relative to the capsule or tablet form.

Most commonly used in children:

* Prilosec? - U.S. /Losec? - Canada (Omeprazole) - Studies have shown that omeprazole suspension is stable for 14 days at room temperature (22° C) and for 30 days when refrigerated (4° C).
FOR ORAL ADMINISTRATION
Open capsule and add granules to an acidic beverage with a pH <5.3 (orange, cranberry, tomato, pineapple juice). Have the patient drink the beverage immediately without crushing or chewing the enteric-coated granules
Suspension for administration through gastric tube:
Administer the suspension through a gastric tube, shaking prior to administration, then flush with 10 mL of tap water and clamp the tube for at least one hour.

* Prevacid? (Lansoprazole) - In addition, an oral suspension formulation of lansoprazole (Prevacid?) was FDA-approved in January 2002. The new formulation is available as 15 mg and 30 mg strawberry-flavored packets. These packets are mixed with 2 tbsp of water just prior to ingestion. Mixing with other liquids or foods is not recommended.

Studies have shown that lansoprazole suspension is stable for 8 hours at room temperature (22° C) and for 14 days when refrigerated (4° C).
ORAL ADMINISTRATION
The enteric-coated granules of lansoprazole can be mixed with soft foods or acidic juices.
Soft foods: Empty the enteric coated granules of 1 lansoprazole capsule onto a tablespoon of applesauce, ENSURE pudding, cottage cheese, yogurt, or strained pears and administer immediately (within 30 minutes) without crushing or chewing the granules.
Juices: Granules can also be mixed with 60 ml (2 ounces) of either apple, cranberry, grape, orange, pineapple, prune, tomato, or V-8 vegetable juice and administered immediately (within 30 minutes) as long as the granules are not crushed or chewed.
Suspension for administration through gastric tube:
Administer the suspension through a gastric tube and flush with 10 mL of tap water.
Administration of the granules through a naso-gastric/gastrostomy tube:
The enteric-coated granules can also be administered through a gastric tube. According to the packet insert, the contents of 1 lansoprazole capsule can be mixed with 40 ml of apple juice and injected into a nasogastic tube. The tube should then be flushed with additional apple juice, so as to assure the complete delivery of the dose.

* Zegerid? (Omeprazole + Sodium Bicarbonate) -
o Both capsules and powder for oral suspension are immediate-release formulations. Both facilitate immediate release of omeprazole for rapid absorption with peak plasma levels being reached in ~30 minutes
o Sodium bicarbonate protects omeprazole from acid degradation by raising intragastric pH
o No enteric coating on capsules or powder for oral suspension

ZEGERID should be taken on an empty stomach at least one hour prior to a meal. ZEGERID is available either as 40 mg or 20 mg capsules with 1100 mg sodium bicarbonate. ZEGERID is also available either as 40 mg or 20 mg single-dose packets of powder for oral suspension with 1680 mg sodium bicarbonate.
Directions for Use:
Capsules: Swallow intact capsule with water. DO NOT USE OTHER LIQUIDS. DO NOT OPEN
CAPSULE AND SPRINKLE CONTENTS INTO FOOD.
Powder for Oral Suspension: Empty packet contents into a small cup containing 1-2 tablespoons of water. DO NOT USE OTHER LIQUIDS OR FOODS. Stir well and drink immediately. Refill cup with water and drink.

Other proton pump inhibitors:

* Aciphex? (Rabeprazole)
* Nexium? (Esomeprazole) - Studies have shown that omeprazole suspension is stable for 14 days at room temperature (22° C) and for 30 days when refrigerated (4° C).
ORAL ADMINISTRATION
Open capsule and add granules to an acidic beverage with a pH <5.3 (orange, cranberry, tomato, pineapple juice). Have the patient drink the beverage immediately without crushing or chewing the enteric-coated granules.
Suspension for administration through gastric tube
Administer the suspension through a gastric tube, shaking prior to administration, then flush with 10 mL of tap water and clamp the tube for at least one hour.
* Protonix? (Pantoprozole)

MOTILITY AGENTS (PROKINETICS)

Prokinetics work by moving food through digestive system faster. The rationale behind using prokinetics for treating reflux is simply that the faster food travels out of the stomach, the less chance there is for it to be refluxed. As well, some estimate as many as 50% of babies with reflux also have some degree of gastroparesis or delayed gastric emptying.

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This class of drugs work to increase the speed at which stomach contents move through the digestive track. How they do this depends on the drug itself as listed below.

* Reglan? - U.S. /Maxeran? Canada (Metoclopramide)
This drug is a dopamine antagonist which is beneficial in the GI tract where dopamine inhibits motility. It stimulates and coordinates esophageal (esophagus), gastric (stomach), pyloric (valve between the stomach and small intestine), and duodenal (small intestine) peristalsis. Peristalsis refers to the smooth, rhythmic muscle contractions that cause food to pass through the digestive tract. It also works to increase lower esophageal sphincter (LES) tone and stimulates gastric contractions. Unfortunately, metoclopramide crosses the blood-brain barrier which can cause negative (and if not discontinued-possibly irreversible) side effects such as involuntary muscle spasms, motor restlessness, and inappropriate aggression. These side effects are more common in long term use (12 or more months). MORE INFO ON REGLAN >
* Motilium? - (Domperidone) - Currently not available in the U.S.
This is also a dopamine antagonist; however, domperidone does not cross the blood-brain barrier so it does not have the undesirable side effects that metoclopramide may. It works to increase esophageal peristalsis, LES pressure and gastric contractions.
* Erythromycin - An antibiotic with the side effect of increasing gastric motility. This is currently being widely used in low doses (not the higher antibiotic doses) for delayed gastric emptying as this does not have the unfortunate side effects that are possible with metoclopramide.
* Urecholine? (Bethanchol) - Urecholine is used to treat urinary and bladder problems. It helps to empty the bladder and often stimulates gastric motility, increases gastric tone, and restores rhythmic peristalsis improving gastric emptying time.

Final Comments

Very few of the drugs used on babies and children for treating GERD have been FDA approved to do so. When a drug is used for something other than it's FDA approved usage, it's referred to as "off-label".