Drugs For GI Problems

6.10.06

Nausea and vomiting
Antiemetics
• Anticholinergics* e.g. hyoscine - side effects: dry eyes, dry mouth, can affect urinary retention in old men.
• Antihistamines* e.g. promethazine - causes drowsiness.
• Phenothiazines+ e.g. prochloperazine - work on chemoreceptor trigger zone and vomiting centre - very effective.
• Dopamine receptor antagonists+ e.g. metoclopramide - work on chemoreceptor trigger zone and vagal afferent.
• 5-HT3 antagonists e.g. ondansetron - used for cancer-induced nausea.
• Others e.g. dexamethasone.

*Work on vomiting centre.
+Drugs of choice.

Dyspepsia
Symptoms
• Epigastric discomfort.
• Anorexia.
• Retrosternal pain.
• Nausea.
• Vomiting.
• Fullness.
• Early satiety.
• Heartburn.

Aetiology
• GORD - 15-25%.
• Ulcers - 15-25%.
• Stomach cancer - 2%.
• NUD - 60%.

Causes
• Acid reflux.
• Abnormalities of gastric acid secretion e.g. gastrin-secreting tumour i.e. Zollinger-Ellison syndrome.
• H. pylori - produces inflammation - hypersecretion of HCl.
• Stress - vagus nerve stimulates over-production of gastrin and histamine.
• NSAIDS, steroids, alcohol and other drugs.

Age-related management
Dyspepsia


<45>45 years


Nil alarming Alarm signs



Endoscopy

Alarm signs
Anorexia.
Loss of weight.
Anaemia.
Rapid progression.
Malaena.
Dysphagia/odynophagia.

Treatment
• Bismuth - coats mucosa - rarely used any more.
• Antacids - neutralise acid - remove symptoms at low doses - curative at high doses.
• PPIs - at apex of cell - more potent than H2A.
• H2 antagonists - at base of cell.
• Antibiotics - eradicate H. pylori.
• Anticholinergics.

Antacids
• Weak alkali.
• Relieve symptoms.
• Increase gastric emptying.

GORD
• Incompetent gastro-oesophageal sphincter.
• Hiatus hernia.
• May results in strictures.

Treatment
• Antacids and alginate.
• High-dose PPI - anti-secretory.

Diarrhoea
• Common complaint.
• Often settles spontaneously.
• Treat CAUSE rather than symptom.

To treat symptom:
• Stimulate opioids receptors - disrupt peristalsis - more time to digest.
-Loperamide/diphenoxylate/codeine phosphate.
• Absorbents:
-Kaolin.
• Anti-spasmodics (antincholinergics):
-Mebeverine/propantheline.

Constipation
• Bulking agents.
• Osmotic agents.
• Stimulants.
• Faecal softeners.

Inflammatory bowel disease
• Ulcerative colitis/Crohn's disease.

Anti-inflammatory drugs
• Steroids (oral, enema).
• Azathioprine.
• Sulphalazine (=sulphapyridine + 5-ASA).
• 5-ASA:
-Mesalazine (sustained release).
-Osalazine (2 x 5-ASA).