Clinical Pharmacology of Alimentary Flashcards
drugs for acid suppression
antacids
h2 receptor antagonists
proton pump inhibitors
drugs effecting GI motility
anti emetics
anti-muscarinics
anti-motility
drugs for IBD
aminosalicylates
corticosteroids
immunisuppressants
biologics
drugs affecting intestinal secretions
bile acids sequestrants and ursodeoxycholic acid
what do antacids contain?
magnesium or aluminium
what do antacids do?
neutralise gastric acid
when should you take antacids?
when symptoms occur
what is the function of alginates?
forms a viscous gel that floats on stomach contents and reduces reflux
function of h2 receptor antagonists?
block histamine receptor thereby reducing acid secretion
function of proton pump inhibitors
block proton pump and thereby reduce acid secretion
does prokinetic agents increase or decrease gut motility and gastric emptying
increase
what is the mechanism of action of GI motility?
invoolved parasympathetic nervous system control of smooth muscle and sphincter tone
what is the mechanism of action for drugs that decrease motility?
via opiate receptors in GI tract to decrease ACh release
decrease smooth muscle contraction and increases anal sphincter tone
what are the three mechanisms of anti-spasmodics
Anti-cholinergic muscarinic antagonists (hyoscine buscopan, mebeverine)
inhibit smooth muscle constriction in the gut wall, producing muscle relaxation and reduction spasm.
Direct smooth muscle relaxants
Calcium-channel blockers (peppermint oil) reduce calcium required for smooth muscle contraction
what are the 4 types of laxatives?
bulk- isphagula
osmotic- lactulose
stimulant- senna
softners- arachis oil
issues of laxatives
obstruction
route of administration-oral or rectal
need for other measures
misuse
concerns and contraindications for corticosteroids
Osteoporosis
Cushingoid features including weight gain, DM, HT,
Increased susceptibility to infection
Addisonian crisis with abrupt withdrawal
function of immunosuppressants
prevents the formation of purines required for DNA synthesis so reduces immune cell proliferation
contraindications of Infliximab
Current TB or other serious infection
Multiple sclerosis
Pregnancy/breast feeding
adverse effects of Infliximab
Risk of infection, particularly TB so all patients should be screened Infusion reaction (fever, itch) Anaemia, thrombocytopenia, neutropenia ?Demyelination Malignancy
drugs affecting biliary secretions
cholestryamine
ursodeoxycholic
function of cholestryamine?
Reduces bile salts by binding with them in the gut and then excreting as insoluble complex
May affect absorption of other drugs so should be taken separately
May affect fat soluble vitamin absorption so may decrease vitamin K levels (affecting clotting and warfarin)
what is ursodeoxycholic acid used to treat?
gallstones and primary biliary cirrhosis
function of ursodeoxycholic acid?
Inhibits an enzyme involved in the formation of cholesterol, altering amount in bile and slowly dissolving non-calcified stones
what processes can GI or liver disease affect?
absorption
distribution
metabolism
excretion
what are the problems with distribution?
low albumin
what are the problems with metabolism?
liver enzymes- toxicity
increased gut bacteria
gut wall metablism- disease may reduce first pass metabolism
what are the problems with biliary excretion
biliary excretion
what are the changes to gut bacteria from GI adverse effects
Mainly antibiotics
Loss of OCP activity
Reduced vitamin K absorption (increased prothrombin time)
Overgrowth of pathogenic bacteria (e.g. Clostridium difficile)
what would be a type A ADR?
intrinsic hepatoxicity
what would be a type B ADR?
idiosyncratic hepatoxicity
risk factors for drug induced liver injury
age sex- female alcohol consumption genetic factors malnourishment
what drugs should you not give to patient with liver disease?
drugs which are hepatic
drugs which may worsen the non-liver aspectw of liver disease
drugs which can be toxic due to changes in pharmacokinetics
what effect can aspirin and NSAIDs have with bleeding?
increase bleeding time
what effect can have NSAIDs have on ascites?
worsen due to fluid retention
