Alimentary pharmacology Flashcards
What are the 3 main types of medications used in acid suppression?
antacids
H2 receptor antagonists
proton pump inhibitors
What are the main 3 types of medications used to affect GI motility?
anti emetics - stop vomiting
anti -spasmodics/anti-muscarinics
anti-motility
What medications are used for IBD?
5ASA - aminosalicylates
corticosteroids
immunosuppressants
biologics
What 2 types of medications are used to affect intestinal secretions?
bile aid sequestrants
usodeoxycholic acids
How do H2 receptor antagonists work?
block histamine receptor to decrease acid production
What conditions are H2 receptor antagonists used?
GORD/peptic ulcer disease
How do antacids work?
neutralise the acid once it has been produced and are usually taken after the onset of symptoms
How do PPI’s work and what is meant by triple therapy?
same as H2 receptor antagonists but work on the proton pump inhibitor with potassium to generate the acid and are used for the same conditions
Used with 2 types of antibiotics for H.pylori infection
How do alginates work? Name an example
form a gel viscous layer over the stomach contents to reduce reflux eg gaviscon
What are prokinetics, why are they used and how do they work?
increase gut motility and gastric emptying
gastroporesis, GORD and with anti emetics
parasympathetically control smooth muscle and sphincter tone via Ach
What are medications which decrease gut motility used for and how do they work?
prevent diarrhoea but can cause constipation
act on opiate receptors to prevent Ach release
decrease smooth muscle contraction and increase anal sphincter tone
What are anti-spasmodics used for and what are the 3 types?
reduce IBS, renal colic symptoms and pain
anti-cholinergic muscarinic antagonists
direct smooth muscle relaxants
CCB eg peppermint oil
How generally can laxatives work? What are the 4 types?
Increase faecal bulk or draw fluid into the gut lumen
bulk, osmotic, stimulant, softener
What are the main issues with laxatives?
obstruction - constipated in IBS
addictive
rout of administration
need for other measures eg fluid intake
5ASA - what are the cautions?
renal impairment, salicylate allergy,
can cause GI upset and blood dyscrasia
Contraindications of corticosteroids?
osteoporosis and susceptibility to infections
Why should you not stop long term steroids abruptly?
Addisonian crisis
How do immunosuppressants work and what are some possible side effects?
prevent purine required for DNA syntheisis
bone marrow suppression and organ damage
What do biologics prevent the action of?
cytokines in the inflammatory response
What other conditions are biologics used in and what are the side effects especially of infliximab?
psoriasis, rheumatoid arthritis
TB, malignancy
What is cholestyramine used in and what may it effect?
pruiritis for biliary causes
reduce bile salts and bind to the bilirubin for excretion
can bind to other drugs/fat soluble vitamins
What Is ursodeoxycholic acid used for and how do they work?
gallstones and PBC
dissolve non calcified stones and inhibit enzyme involved in cholesterol formation
Explain how GI or liver disease can effect ADME
A - pH, gut length, transit time
D - low albumin
M - liver enzymes
E - biliary excretion
What are the main medications which cause drug induced diarrhoea?
antimicrobials
What are some medications that can cause GI bleed and how can these be overcome?
low dose aspirin, warfarin, NSAIDS
using clopidogrel instead of aspirin for 1st line defence
using NOACs instead of warfarin
What is the difference between type A and B ADR in retrospect to hepatotoxicity?
A - dose related, predictable, acute, intrinsic hepatotoxicity
B - unpredictable, happen at any time, not dose related - hypersensitivity reaction - due to drug/metabolite can cause LFT rise –> death but usually hepatitis or cholestasis
Risk factors for drug induced liver injury?
age, female, malnourishment, genetics, alcohol
What is taken into account with the child-pugh classification?
bilirubin, albumin, PT prolonged, encephalopathy and ascites
What does the child pugh classification determine?
cirrhosis mortality and liver transplantation
What types of drugs should be taken care with or avoided in liver disease?
hepatotoxic drugs
toxic due to pharmacokinetics eg liver metabolism
worsen non liver aspect of liver disease eg encephalopathy
What specific medications should be taken care with in liver disease?
warfarin - clotting factors already low
aspirin/NSAIDS - worsen ascites
opiates - precipitate encephalopathy
