Drugs for upper GI Flashcards
What are the 8 drug classes we learned from this lecture
1) Antacids
2) hIstamine 2 receptor agonists
3) Proton pump inhibitors
4) Antiemetics
5) Protective barriers
6) Misoprostol
7) Prokinetic drugs
8) Antimuscarinics
90) Gastrin receptor antagonists
What are the 3 antacids we know?
Mg(OH)2- milk of magnesia
CaCO3- Tums
Al(OH)3- Gaviscon
What is the MOA of Antacids
increase gastric pH
neutralize acid
What are the pharmacokinetics of Anacitds
AL,ca and mg no absobed
May chelate other drugs, affecting their absorption
altered pH may affect drug absorption
When to use antacids (2)
Heartburn/mild Gerd
dyspepsia
Are there any contraindications for Antacids
no major ones :)
Side effects of Antacids
Bleching
Ca-hypercalcemia->possibel calculi formation
Al-containing- constipation and hyophosphatmia
Mg- diarrhea
What is the end sound for H2 receptor antagonists
tidine
what is MOA of H2 receptor antagonists
Competitive selective block of histamine h2 receptors
Reduced but not eliminated acid secretion
up to 60-70% reduction
because ACh and Gastrin pathways still available in response to food-related stimulus
What is the most effective drug at reducing nocturnal acid secretion
H2 receptor antagonists
Pharmacokinetics of H2 receptor antagonists
oral and intramuscular and intravenous fomulation
only 50% oral bioavaliblity
peak absorption at 1-3 hrs
What are the indications for H2 receptor antagonists (4)
Dyspepsia
GERD
Peptic ulcer disease
Prevention of bleeding from stress-related gastritis
What are the contraindications for H2 receptor antagonists
none
no known harm to fetus
Side effects of H2 receptor antagonists
diarrhea/consitpation
headache
drowsiness/fatigue
muscle pain
Rare CNS symtoms
What is the ending of PPI’s
prazole
MOA of PPI’s
Irreversible inactivation of proton pump common to all triggers of gastric acid secretion vell affected will never secrete again
Decrease H+ secretion by 90-98%
restoration of function requires new Proton pump synth-> 18-24 hrs
once-daily oral treatment
relatively selective for parietal cell proton pumps
Indication for PPIs
Gystic and duodenal ulcer h.pylori associated Nsaid induced GERD prevention of bleeding from stress-related gastritis Gastric hypersecretory conditions like Zollinger-Ellison syndrome
Contriinidcation for PPIs
None :)
Side effects PPIs
non really but flatulence nausea abdominal pain diarrhea or consitpation
Antimuscarinics for Stomach
pirenzipine
utile effective but side effects
Gastrin receptor antagonists
Proglumide
pathway inhibited at pH
H.pylori triple therapy
for 2 weeks
PPI+clarithromycin + (metonidizole or amoxicillan)
then 6week just PPI
What does Misoprostol do
Misoprostol is a Prostaglandin E1(PGE1) analogue and inhibits parietal cells and stimulates mucus cells
Pharmacokinetics of Misoprostol
Short half-life -frequent dosing
no impact on cytochrome P450 enzyme
Indication for Misoprostol
NSAID induced ulcers
Contraindication for Misoprostol
pregnancy its a strong uterine stimulant
Side effects of misoprostol
Diarrhea
abdominal cramping
uterine contraction
What is Sucralfate and what is its MOA
Al(OH)3- sucrose sulfate complex acid release anionic sulphated sucrose binds to charged proteins in ulcer viscous sticky, protective barrier indirect stimulation of PGE2-production
Pharmacokinetics of sucralfate
Take on empty stomach
localized action /minimal systemic absorption
short effect (~6hrs)
Indication for Sucralfate
Gastic and duodenal ulcer
Contraindications for Sucralfate
None
Side effects of Sucralfate
Al3 induced constipation
may reduce the absorption of other drugs
What is the mechanism of action of bismuth subsalicylate (Peptobismul)
Coat ulcers-> physical protective barrier
increase PGE2, HCO3 and mucus production
antimicrobial
reduces stool frequency
Pharmacokinetics of bismuth subsalicylate (Peptobismul)
dissocaites in stomach acts locally
only salicylate substantially absorbed
indication for bismuth subsalicylate (Peptobismul)
H.pylori ulcer
acute diarrhea
Contraindication of bismuth subsalicylate (Peptobismul)
Children with viral infection-> reyes syndrome
allergies to ASA (30 mL~325 mg tablet
Side effects of bismuth subsalicylate (Peptobismul)
Black stool
black tounge
constipation
What are the two prokinetic drugs we know
Metoclopramide and domperidone
