GIT Pharmacology Flashcards by Viiiiii Hendricks

Ranitidine MOA

block H2 receptor,

reduce acid secretion

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H2-receptor antagonists side effects

general stuff-headache, dizziness, skin rash, nausea, diarrhoea, confusion
impotence and gynaecomastia (rare)

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H2-receptor antagonists beware

 Elimination mainly via kidneys-so if kidney issue then have to reduce dose

cimetidine interacts with CYP450 enzymes of the liver –ie it can interfere with other drugs

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other antisecretory drugs for PUD

Antimuscarinics
Gastrin antagonists
Somatostatin analogues

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PPI side effects

very safe, maybe headache, rash, dizziness, rarely gynecomastia and renal impairment

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PPI MOA

irreversibly inactivating H+/K+ ATPase proton pump

=reduced secretion of HCl

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PPI things to remember

Drug is inactive at a neutral pH, becomes activated in acidic environment

taken 1 hr before meal

dont giv in pt using antacid -wont work cos envrio will be neutral thanks to antacid

Inhibits CYP450 enzymes – drug interactions (but not all –prazoles do this)

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PPI core drug

Esomeprazole

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sucralfate

for PUD

creates a viscous coating on ulcer

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Things that increase the defence side in PUD (aka Cytoprotective agents and mucosal strengtheners)

	Sucralfate
	Prostaglandin analogues
 	Bismuth chelate
	Carbenoxolone
	Antacids

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bismuth chelate side effect

may cause blackening of stools & tongue

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PGE1 analogue (a Prostaglandin analogues) contraindicated in

pregnancy

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carbenoxolone job-

this drug is a herbal thingy

promotes the production of mucus

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Carbenoxolone AE

alkalosis, hypertension and

hypokalaemia

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Antacid job

a weak base that neutralises the acid lol

also inhibit pepsinogen forming to pepsin

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antacid side effect

Al3+ antacids-constipation

Mg2+ antacids- diarrhoea

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antacid beware

antacid interacts with a lot of other drugs

SO avoid taking antacid 2 hrs before/after taking other drugs

sucralfate -wen to take

1 hr before meals 4 times a day

Do not take antacids or meals within 30min of sucralfate – raised gastric pH alters action of sucralfate

triple therapy

antibiotic treatment for PUD (first line)

PPI + metronidazole + amoxicillin or clarithromycin = triple therapy

drugs promoting reflux-ie bad for GORD

anticholinergics
• phosphodiesterase inhibitors
• nitrites
• calcium channel blockers
• dopamine agonists

GORD treatment

PPIs (drug of choice)

antacids, H2 receptor antagonists, sucralfate

osmotic laxatives

o Basically poorly absorbed salts or sugars that draw water into gut so that stuff moves faster.

o Risk of dehydration
o Can cause abdo cramps
o Avoid in kids/ renal damage

bulk laxatives

o BULK LAXATIVES: Basically this sugar compound that is poorly digested and draws in water in lumen forming a bulky hydrated lump in lumen. This increase in mass is a stimulant for peristalsis to occur, water also helps as lubricant

whats the Faecal softeners for constipation

– docusate sodium

osmotic laxatives

o Basically poorly absorbed salts or sugars that draw water into draw water into the contents, softening it and allowing stuff to move faster. o Risk of dehydration o Can cause abdo cramps o Avoid in kids/ renal damage

bulk laxatives | eg metamucil

whats the Faecal softeners for constipation

– docusate sodium | surfactant/detergent-like effect

 Stimulant laxatives

increase electrolyte and water secretion by mucosa, increases peristalsis aloe, enna, cascara, bisacodyl, glycerol suppositories

Constipation treatemnt

purgatives.

purgatives include:

laxatives faecal softeners stimulatant laxatives D2 receptor antagonist

Opioids e.g. loperamide job | Antidiarrhoeal Agent^

decreases activity of myenteric plexus

diarrhoea treatment

fluid n electrolyte balance (glucose ‘drinks’ enhance Na+ (and water) absorption) antiinfective agents eg antibiotic or antiviral Traveller’s diarrhoea = E.coli antidiarrhoeal agent -opioid don't give muscarinic antagonist

treatment of vomiting

assess cause, replenish water/electrolytes anti-emetic drugs

anti-emetic drugs

Antimuscarinics Antihistamines Dopamine (D2) receptor antagonists 5-HT3 antagonsits

anti-emetic drugs

Antimuscarinics Antihistamines Dopamine (D2) receptor antagonists 5-HT3 antagonsits ``` other: Pyridoxine (vitamin B6) Ginger Carob bean Cannabinoids ```

antimuscarinics -for vomiting

Hyoscine prophylaxis and treatment Blocks ACh receptors

antimuscarinics -for vomiting

Hyoscine prophylaxis and treatment MOA: Blocks ACh receptors se:Blurred vision, urinary retention, decreased salivation, drowsiness

Antihistamines -for vomitin

H1 receptor antagonists (H2 is for peptic ulcers) Not useful in chemotherapy induced se:Blurred vision, urinary retention, dry mouth

Dopamine (D2) receptor antagonists -for vomitin

e.g. domperidone MOA;block D2 receptors in CTZ

5-HT3 antagonsits-for vomiting

e.g. ondansetron MOA:Works at CTZ, also has a peripheral action Prevent vomiting in 70-80% of patients on chemotherapy Side Effects: constipation

albendazole

drug of choice for mixed intestinal worm infections