Nausea/Vomiting/Constipation/Diarrhoea drug Flashcards
note the more important drugs (just tap to see)
N/V:
- chemotherapy induced (the 3 classes) + motion sickness (H1/M1 drugs)
contipation
- break it down into physiological or mechanical cause and then the general drugs for them
- common approach: osmotic and bulk forming laxatives, stimulant laxatives
- others are less frequently used
diarrhea:
- opioid antagonist = for rapid acting control (loperamide)
- kaolin/pectin
- bismuth compounds = for infectious diarrhea
- others are less frequently used
meq:
will test more important conditions or more more severe conditions
what are the different types of GIT drugs?
- nausea and vomiting
- diarrhoea and constipation
- anti-peptic ulcer
what are the mechanisms that trigger nausea and vomiting?
- chemoreceptor trigger zone in CNS (floor of 4th ventricle) - has dopamine receptors, neurokinin receptors and 5-HTC receptors too
- GIT (5-HTC receptor)
- vestibular system (in the ear)
what are the classes of drugs used in combatting chemotherapy-induced vomiting?
- serotonin 5-HTC antagonist
- corticosteroids
- neurokinin receptor antagonist
what are drug examples of serotonin 5-HTC antagonists and the MOA?
any -setron
works by inhibiting 5-HTC receptor in GIT (not so much in chemoreceptor trigger zone because 5-HTC is less significant there)
NOTE: does not work for delayed nausea
what is the side effect of serotonin 5-HTC antagonist?
QT prolongation
what are the drug examples of corticosteroids and the MOA?
dexamethasone
targets vomiting more so than nausea
what are the drug examples of neurokinin receptor antagonist and its MOA?
any -prepitant
inhibits the neurokinin receptors in CTZ
what is the side effect of neurokinin receptor antagonist?
many DDI’s
what are other drugs that can help with nausea and vomiting, that are not specific for helping chemotherapy-related?
- dopamine receptor antagonists
2. muscarinic and histamine receptor antagonists
how do we cure anxiety-induced nausea and vomiting?
can give benzodiazepines (e.g. lorazepam and diazepam)
moving past anti-nausea and vomiting, let’s go to diarrhoea and constipation drugs - what are the drug classes to cure diarrhoea?
- make poop harder
- increase transit time
- cure H. pylori
moving past anti-nausea and vomiting, let’s go to diarrhoea and constipation drugs - what are the drug classes to cure constipation?
- make poop softer
2. decrease transit time
what are the anti-diarrhoea drugs that help make poop harder?
2 types
- kaolin/pectin
- absorbs bacterial toxin/fluid - bile salt resin
- binds to bile salt and prevents diarrhoea caused by excessive focal bile salt
what are the anti-diarrhoea drugs that help to decrease transit time?
2 types
- opioid antagonist
- shuts down GIT motility and secretion - somatostatin-like peptides e.g. octreotide
- decreases intestinal motility and secretion; and also in the gall bladder and pancreas so that you decrease those secretions as well
what are the anti-diarrhoea drugs that help to cure H. pylori?
2 types
in antimicrobials, you still about OAC (omeprazole, amoxicillin and clarithromycin)
but here, we think about:
- bismuth compounds
- binds to the enterotoxin and is mucoprotective - products of lactobacillus acidophilus
- competitive inhibition with h. pylori for the intestinal wall
what are the anti-constipation drugs that help to make poop softer?
3 types
- bulk-forming laxative
- absorbs water and forms bulks that stimulate peristalsis - osmotic laxative
- induces water osmosis into poop - surfactant
- decreases surface tension so water can enter poop
what are the anti-constipation drugs that help to decrease transit time?
4 types
- opioid antagonist
- inhibit the receptors that decrease GI motility and secretion - Chloride channel activators
- increase secretion and motility in small intestine - stimulant laxative
- produce colonic contractions = increase peristalsis - 5-HT4 receptor antagonist
- increase peristalsis and colonic movement
what are the drug classes for anti-peptic ulcer drugs?
HAP (help) Suffering Busy Misses Clear Amassing Asshole work
[receptor/electrolyte stuff]
H: h2 receptor antagonist
A: antacid
P: proton pump inhibitor
[protective mucosal stuff]
S: sulfacrate
B: bismuth compounds
M: misoprostol
[antibiotics]
C: clarithromycin
A: amoxicillin
M: metronidazole/omeprazole
minus the antibiotics and anti-protozoal, we’ll talk about the rest
what are examples of and the MOA of antacids?
antacids are any weak base
MOA: neutralises acid to form salt and H2O
what is the administration of antacids?
not very potent so you need to give a lot
either given as a liquid (faster) or tablet
what is the side effect/precautions of antacids?
- metabolic alkalosis and milk-alkali syndrome
- DDI’s
- Na salt and fluid retention = no good for HTN or renal insufficiency
hence, can be given with Mg and Al supplements
what are examples of and MOA of proton pump inhibitors?
omeprazole
inhibits H/K ATPase and hence inhibits gastric acid secretion by gastric parietal cells
what is the administration of proton pump inhibitors?
taken on empty stomach
what are the side effects/precautions of proton pump inhibitors
honestly, relatively safe
what is the MOA of sulfacrate?
forms a protective gel over the ulcer and stimulates mucosal prostaglandin and bicarbonate secretion
what is the MOA of bismuth?
same as sulfacrate
what is the MOA of misoprostol?
analogue for PGE1 and binds to the receptor to stimulate mucus and bicarb secretion
