Pharmacology of the GI Tract Flashcards
What are the main types of metabolism that occur in the liver?
- Carbohydrate metabolism
- Fat metabolism
- Protein metabolism
What are some common substances stored in the liver?
Vitamin A, B12, E, D and K
Copper
Iron
Glycogen
The liver produces which coagulation factors?
II, VII, IX and X
Which main plasma protein is produced in the liver?
Albumin
Which substance, when released stimulates bile to be released from the sphincter of Oddi?
CCK
When chyme is present in the duodenum, which two factors cause smooth muscle contraction?
CCK
Vagal impulses
How are bile salts formed?
When bile acids react with sodium or potassium
Which antibody class is present in bile?
IgA
What is bilirubin?
The breakdown product of the porphyrin component of haemoglobin
Which excretions from the body is bilirubin responsible for colouring?
Faeces - brown
Urine - yellow
What is jaundice?
The increase in blood levels of bilirubin
What is cholelithiasis?
Formation of gallbladder stones
For patients who cannot undergo surgery, which drug can be given to aid with dissolving the gallstones?
Ursodeoxycholic acid
Why is morphine not a suitable painkiller for gallstone-related pain?
It constricts the sphincter of Oddi and increases intrabiliary pressure worsening any problems present
Which drugs can be given for gallstone pain?
- Buprenorphine
- Pethidine
How may biliary spasm be relieved?
- Atropine
- GTN
Why are hardly any bile salts lost in the faeces?
Enterohepatic recycling
Bile salts in the ileum are taken up by sodium coupled transporters
Which transporters will transport bile salts back into hepatocytes, after their uptake from the terminal ileum?
Sodium coupled transporters
What happens when bile salt concentration is reduced?
More is propared from cholesterol
(this indirectly lowers plasma LDL levels)
Give examples of bile acid sequestrates, or resins
- Colesevelam
- Colestipol
- Colestyramine
What is the purpose of resins?
They can bind to bilse salts and prevent their reabsorption
This will indirectly lower cholesterol because more bile salts must be synthesised from cholesterol in the body
LDL receptor activity of liver cells increases to achieve this
How many phases does drug metabolism generally contain?
2
Why is it dangerous to stop smoking during drug treatment?
Smoking inceases liver enzyme activity, so more drug is required to have an effect
If smoking is stopped, the liver activity is reduced and less drug is required so continuing the same dose could lead to overdoses and serois side effects
Name a large family of enzymes in the liver able to participate in drug metablism
The cytochrome p450 family of mono-oxygenases