objective 2.5 (1) Flashcards
what does the stomach secrete?
- Hydrochloric acid (HCl)
- Bicarbonate
- Pepsinogen
- Intrinsic factor
- Mucus
- Prostaglandins
what are the glands of the stomach?
cardiac
pyloric
gastric
Produce and secrete hydrochloric acid; Primary site of action for
many of the drugs used to treat acid-related disorders
parietal cells
Secrete pepsinogen, a proenzyme; pepsinogen becomes pepsin when
activated by exposure to acid; Pepsin breaks down proteins (proteolytic)
chief cells
Mucus-secreting cells (surface epithelial cells); Provide a protective
mucus coat; Protect against self-digestion by hydrochloric acid and digestive
enzymes
mucous cells
Secreted by parietal cells when stimulated by food, caffeine,
chocolate, and alcohol; Maintains stomach at pH of 1 to 4; Acidity aids in the
proper digestion of food and defenses against microbial infection via the
gastrointestinal tract.
* Secretion also stimulated by:
* Large fatty meals, Emotional stress, Excessive amounts of Caffeine, chocolate, and alcohol
increase stimulation and cause problems, ie. PUD
hydrochloric acid
Gastric or duodenal ulcers that involve digestion of the
GI mucosa by the enzyme pepsin
peptic ulcer disease
Bacterium found in GI tract of 90% of
patients with duodenal ulcers and 70% of those with gastric ulcers.
* Triple therapy includes a proton pump inhibitor (PPI) and antibiotics
helicobacter pylori
GI lesions are a common finding in Critical
Care Unit patients, especially within the first 24 hours after admission.
* Factors include decreased blood flow, mucosal ischemia, hypoperfusion,
and reperfusion injury
stress-related mucosal damage
antacids, H2 antagonists, and PPIs
acid controlling drugs include
used to reduce the pain and reflux
associated with acid-related disorders.
* Raising the gastric pH 1 point (1.3 to 2.3) neutralizes
90% of the gastric acid.
* Antacids are basic compounds used to neutralize
stomach acid.
* Salts of aluminum, magnesium, calcium, or sodium
bicarbonate, or all of these.
antiacids
what is the MOA of antacids?
- Work by neutralizing gastric acidity.
- To give acute relief of symptoms associated with peptic ulcer, gastritis,
gastric hyperacidity, and heartburn - They do not prevent the overproduction of acid.
- Promote gastric mucosal defensive mechanisms
protective barrier against hydrochloric acid
mucus
helps buffer acidic properities of hydrochloric acid
bicarbonate
prevent activation of proton pump
prostaglandins
what are the drug effects of antacids?
- Reduction of pain and reflux associated with acid-related disorders
- Raising the gastric pH 1 point (1.3 to 2.3) neutralizes 90% of the gastric acid.
- Reducing acidity reduces pain as a result of:
- Base-mediated inhibition of the protein-digesting ability of pepsin
- Increase in the resistance of the stomach lining to irritation
- Increase in the tone of the cardiac sphincter
what are the contraindications of antacids?
Severe renal failure or electrolyte disturbances: potential toxic
accumulation of electrolytes in the antacids themselves.
* Gastrointestinal obstruction: Antacids may stimulate GI motility.
such as simethicone are used to
relieve the painful symptoms associated with gas
antiflatulents
Have constipating effects so often used with magnesium to counteract
constipation.
Often recommended for patients with renal disease (more easily excreted)
Examples: Antacid plus, Diovol, Gelusil, Maalox.
aluminum salts
Buffers the acidic properties of hydrochloric acid
Highly soluble with quick onset but short duration.
May cause metabolic alkalosis
Sodium content may cause problems in patients with heart failure,
hypertension, or renal insufficiency.
sodium bicarbonate
- Commonly cause diarrhea; usually used with other drugs to counteract this effect.
- Not used in renal failure, failing kidney cannot excrete extra magnesium,
Magnesium builds up. - Examples: Magnesium hydroxide and mineral oil
magnesium salts
- Many forms but carbonate is most common
- May cause constipation, kidney stones – advertised as a dietary calcium
source. - Also not recommended for patients with renal disease—may accumulate to
toxic levels - Long duration of acid action—may cause increased gastric acid secretion
(hyperacidity rebound).
calcium salts
what are the AE of antacids?
Minimal and depend on the compound used.
what are the drug interactions of antacids?
adsorption of other drugs to antacids
chelation
increased stomach pH
increased urinary pH
reduce acid secretions in the
stomach.
* Available OTC in lower-dosage forms.
* Ranitidine hydrochloride (Zantac)
* Famotidine (Pepcid)
* Competitively block the H2 receptor of acid-producing
parietal cells.
* Reduce hydrogen ion secretion from the parietal cells and
increase in the pH of the stomach.
H2 receptor antagonists (blockers)
what are the indications of H2 receptor antagonists
- Relief of many of the symptoms associated with hyperacidity-
related conditions. - Gastroesophageal reflux disease (GERD)
- Peptic ulcer disease (PUD)
- Erosive esophagitis
- Adjunct therapy to control upper gastrointestinal bleeding
what are the AE of H2 receptor antagonists?
- Dizziness, confusion and disorientation in elderly patients.(i.e.
with Zantac) - Thrombocytopenia has been reported with ranitidine
hydrochloride (Zantac) and famotidine.
- May increase drug levels and inhibit the absorption of
drugs that require an acidic GI environment for
absorption. - Largely replaced by ranitidine and famotidine.
- May induce erectile dysfunction and gynecomastia.
cimetidine
- The parietal cells release positive hydrogen ions (protons) during
hydrochloric acid production – called proton pump. - These drugs block the pump and stop hydrogen ion secretion from
the parietal cells. - H2 blockers and antihistamines do not stop the action of this pump
proton pump inhibitors
what are the proton pump inhibitors?
- Rabeprazole (pariet)
- Pantoprazole (pantoloc)
- Omeprazole (losec)
- Lansoprazole (prevacid)
what are proton pump inhibitors used to treat?
- Gastroesophageal reflux disease
- Erosive esophagitis
- Treatment of active duodenal, benign gastric ulcers, and NSAID induced ulcers.
- Stress ulcer prophylaxis
- Treatment of H. pylori–induced infections
- Given with antibiotics
what are the AE of proton pump inhibitors?
- May increase the risk for Clostridium difficile.
- Osteoporosis and risk of wrist, hip, and spine fractures in long-term users.
- Risk for pneumonia.
- Depletion of magnesium.
- Food may decrease absorption of the PPIs, take on an empty stomach.
- Cytoprotective drug, used for stress ulcers, peptic ulcer disease.
- Forms a protective barrier over the base of ulcers to protect
from pepsin. - Do not administer with other drugs
sucralfate
- Prostaglandin E analog that has cytoprotective activity.
- Used for the prevention of NSAID-induced gastric ulcers.
- Thought to inhibit gastric acid secretion
misoprostol
- Antiflatulent drug
- Result is decreased gas pain and increased passing of gas
(burping or via rectum)
simethicone
