GORD Flashcards
Management of GORD
- Reduce/suppress gastric acid secretion
- Mucosal protection (barrier)
- Neutralizing gastric acid
- Eradicate H. Pylori
Proton pump inhibitors mechanism
-prazole’s
- irreversible inhibition of H+/K+ ATPase enzyme (proton pump)
- suppress H+ ions into lumen
Omeprazole: only one that has significant drug interactions (inhibits CYP450) - toxic side effects from other drugs
PPI side effects
- hypomagnesemia (in prolonged use
- risk of fractures and osteoporosis (incomplete absorption of calcium carbonate)
- clostridium difficile associated diarrhea NB
- prevent B12 absorbtion (acid required for absorbtion) -> anemia
H2 receptor antagonists
Reversibly binds H2 receptors in parietal cells of stomach
-gastric acid secretion response to other secretagogues also reduced
(Food, caffeine, Ach, gastrin)
- nocturnal acid hypersecretion: useful
- or in people allergic to PPI’s
H2 receptor antagonists SE
- not in pregnancy
- anti-androgenic effects
Cimetidine
H2RA
-inhibits CYP450 - more interactions
-also can be used to Rx molluscum contagiosum
Ranitidine
H2RA
- as effective as cimetidine, less SE and interactions
- little/no androgenic effects
Prostaglandins
Inhibit HCl secretion, wtimulates mucus and bicarbonate secretion and vasodilation of submucosa
- Misoprostol
- USE only in NSAID induced ulcers
Prostaglandin SE
- not in pregnancy (contraction of uterus)
- nausea & diarrhea
Sucralfate
Mucosal protective agent
- sucrose hydrogen sulphat-aluminum complex
- forms paste like gel when in contact with HCl - barrier
-Don’t use with any other med (at least 2h) - forms unabsorbable complex
Bismuth Subcitrate
High affinity for damaged tissue - coats
SE: blackening of tongue, stools
-renal faiure in prolonged Rx
Alginates
-used in pregnancy
Antacids
-doesn’t block acid production, but neutralizes
- aluminum hydroxide
- calcium carbonate
- magnesium
- sodium bicarbonate
H. Pylori eradication
Triple therapy
-7-14d regimen
1. PPI (for 1mo) Any two of following: -clarithromycin 500mg bd -amoxicillin 1g bd Metronidazole 400mg bd Levofloxacin if resistant to clarithromycin
PPI CI - then use ranitidine + bismuth
Vomiting centre
5HT2 receptors
Achm receptors
H receptors
Stomach & intestines
Stretch receptors
Chemoreceptors
5HT3 receptors
-projections to chemoreceptor trigger zone and vomiting centre
Chemoreceptor trigger zone
D2 (central) receptors
5HT3 receptors
NK1 receptors (NB)
-projections to vomiting centre
Vestibular system
Achm
H1 receptors
-projections to chemoreceptor trigger zone and vestibular center
Antihistamines
-H1 blockers
Antihistamines SE
Anticholinergic SE
Promethazine
F
Cyclizine
F
Betahistine
D
Cinnarizine
F
Phenothiazines
Dopamine antagonists
- most common general purpose anti-emetic
- helpful in hiccups NBNB - numbs phrenic nerve which supplies diaphragm
-extra pyramidal SE
Benzamides
D
Butyrophenones
F
Domperidone
D
Haloperidol
D
Metoclopramide
Dopamine antagonist
- 5HT4 stimulation (prokinetic)
- 5HT3 antagonist at higher doses
- promotes gastric emptying
- all nausea except labyrinth disorders
- anti dopamine effects:
- extrapyramidal Sx
5HT3 receptor antagonists
- chemotherapy induced emesis
- SE: headache, QT interval prolonged (monitor in heart disease)
Ondansetron
F
Granisetron
Ss
Palonsetron
D
Dolasetron
D
Tropisetron
S
Benzodiazepine
D
Neurokinin Antagonists
Aprepitant
-
Corticosteroids
Unknown mechanism of action
- used with cytotoxic drugs - large doses
- combo with NK1 Antagonists and 5HT3 antagonists
Cannabinoids
Dronabinol and Nabilone
- useful in cytotoxic therapy
- blocks descending pathways in cortical centres
Anti muscarinic agents
- decreased GI motlity and secretory activity
- muscarinic receptor blocking in vomiting centre and vestibular centre
-Don’t use in prostatic enlargement, or closed angle glaucoma, or intestinal obstruction
Hyoscine
Anti-muscarinic
- used in preventing motion sickness in short journeys
- not for long term use!
-can be used to relieve smooth muscle spasms (intestinal, biliary, or genitourinary)
Antimuscarinic SE
Think - fight or flight
- cardiac arrhytmias
- dry mouth
- constipation
- urinary retention
- respiratory collapse/apnoea
