1. Treatment for dyspepsia (消化不良), heartburn, GORD
Dyspepsia due to food (spicy, high fibre, fatty, too quick eating, overeating)
Heartburn due to acid from stomach into oesophagus
GORD-heartburn & reguigitation due to weak/open lower oesophageal sphincter caused by pregnancy, obesity and hiatus hernia… can lead to cancer,

Antacid: can be used for all the 5 illness,
Mylanta: alkaline to neutralise acid, mixture of Mg++ and Al+++ hydroxide. Accumulation of Al+++ can lead to osteoporosis and myopathy
Gaviscon: mixture of Ca++ carbonate, Na+ bicarbonate and alignate (helps mucus stick to oesop.)

PPI: can be used for all the 5 illness
Omeprazole, a prodrug- enteric-coated, need acid environment, alkaline pH-intestine, inhibit P450, decrease clearance of benzodiazepine, phenytoin and warfarin
H2 antagonist(ranitidine): only used for the top 3

2. Treatment for peptic ulcer: AB and PPI, antacid, Sucralfate
Peptic ulcer due to H. pylori, excessive acid(imbalance mucous defence and aggressive factor)
AB: combination of amoxicillin and clarithromycin, or with PPI
Sucralfate: produce sticky gel to ulcer and inhibit digestion of mucosal protein which digested by pepsin in intestine. Side effect: antacid can prevent sucralfate, sulcralfate can prevent some drugs

3. Treatment for NSAIDs-induced ulcer: PPI or misoprostol, antacid, Sucralfate
NSAIDs induced ulcer:Non selective inhibitor of COX-aspirin remove cytoprotective prostaglandins (PGI2) Misoprostol: selective agonist at prostaglandins EP receptor inhibiting acid secr, oral, long lasting
Side effect: diarrhoea due to EP stimulate gut mobility; contraction of uterus

4. Treatment for gut motility: Domperidone, Prucalopride, Metoclopramide
Gut motility (peristalsis) due to release of ACH in the enteric nervous system from excitatory motor neurones binding to M2(smooth muscle contraction).DA:D2 receptor agonist, inhibits release of ACH .
Gastroparesis: paralysis of stomach muscle due to loss of neural control with DM. Domperidone
Irritable bowel syndrome: symptoms between diarrhea and constipation

Increase ACH to increase gut motility: D2 antagonist (Domperidone), 5-HT (Prucalopride)
Domperidone: D2 receptor antagonist-prevents DA , increase ACH, increase gut motility—used in GORD,gastroparesis
Prucalopride: selective 5-HT4 receptor agonist. Used in constipation
Metoclopramide: D2 antagonist & 5-HT4 agonist, used in GORD and gastroparesis

5. Treatment for emetics due to cytotoxic drugs, motion sickness, post-operation
Cytotoxic drug: irritate GIT (5-HT3 receptor); chemoreceptor trigger zone(CTZ), 5-HT3-D2-NK1
Ondansetron: 5-HT3 antagonist, acts on CTZ(central) and gut(peripheral)
Prochlorperazine/Metoclopramide: D2 antagonist in CTZ, cytotoxic drug or pregnancy(morning)
Aprepitant: NK1- antagonist(neurokinin) to inhibit substance P (neurotransmitter peptide) binding
Dexamethasone: GCS, inhibit PGE2

Motion sickness: motion monitored by inner ear into cerebellum, H1, M receptor- nausea vomiting
Promethazine: H1 & M antagonist, cross BBB to act on H1&M in cerebellum, make drowzy
Scopolamine: M antagonist, cross BBB. Transdermal patch

Post-op: Prochlorperazine, Metoclopramide, Promethazine, Ondansetron, Scopolamide

6. Treatment for diarrhea:
Due to infection: no need tx, give fluid and electrolyte
Due to malabsorption: lactose intolerance, gluten malabsorption--AB
Due to inflammatory Bowel dx. AB
Loperamide; stimulate GIT u receptor anti-diarrhea (mimicking morphine which can cause constipation by stimulating u receptor decreasing gut motility)

7. Treatment for constipation: high fibre, low fat intake,^ fluid, exercise
Methylcellulose: bulking forming laxatives:poorly fermented-发酵 fibre attracts