Page 1101 - Basic _ Clinical Pharmacology ( PDFDrive )

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Drugs Used in

the Treatment of

Gastrointestinal Diseases

Kenneth R. McQuaid, MD

C ASE STUD Y

A 21-year-old woman comes with her parents to discuss She has no other significant medical or surgical his-
therapeutic options for her Crohn’s disease. She was diag- tory. Her current medications are mesalamine 2.4 g/d and
nosed with Crohn’s disease 2 years ago, and it involves budesonide 9 mg/d. She appears thin and tired. Abdominal
her terminal ileum and proximal colon, as confirmed examination reveals tenderness without guarding in the
by colonoscopy and small bowel radiography. She was right lower quadrant; no masses are palpable. On perianal
initially treated with mesalamine and budesonide with good examination, there is no tenderness, fissure, or fistula.
response, but over the last 2 months, she has had a relapse Her laboratory data are notable for anemia and elevated
of her symptoms. She is experiencing fatigue, cramping, C-reactive protein. What are the options for immediate con-
abdominal pains, and nonbloody diarrhea up to 10 times trol of her symptoms and disease? What are the long-term
daily, and she has had a 15-lb weight loss. management options?

INTRODUCTION bicarbonate secretion, prostaglandins, blood flow, and the pro-
cesses of restitution and regeneration after cellular injury). Over
Many of the drug groups discussed elsewhere in this book have 90% of peptic ulcers are caused by infection with the bacterium
important applications in the treatment of diseases of the gastro- Helicobacter pylori or by use of nonsteroidal anti-inflammatory
intestinal tract and other organs. Other groups are used almost drugs (NSAIDs). Drugs used in the treatment of acid-peptic
exclusively for their effects on the gut; these are discussed in the disorders may be divided into two classes: agents that reduce
following text according to their therapeutic uses. intragastric acidity and agents that promote mucosal defense.

AGENTS THAT REDUCE
■ DRUGS USED IN ACID-PEPTIC INTRAGASTRIC ACIDITY
DISEASES
PHYSIOLOGY OF ACID SECRETION
Acid-peptic diseases include gastroesophageal reflux, peptic ulcer
(gastric and duodenal), and stress-related mucosal injury. In all The parietal cell contains receptors for gastrin (CCK-B), hista-
these conditions, mucosal erosions or ulceration arise when the mine (H ), and acetylcholine (muscarinic, M ) (Figure 62–1).
2
3
caustic effects of aggressive factors (acid, pepsin, bile) overwhelm When acetylcholine (from vagal postganglionic nerves) and gastrin
the defensive factors of the gastrointestinal mucosa (mucus and (released from antral G cells into the blood) bind to the parietal
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