Liver pharmacology

Question 1

functions of the liver?

Answer 1

metabolism of:

• carbohydrates (gluconeogenesis, glycogenolysis, glycogenesis)
• fat metabolism (lipoproteins, cholesterol and trigylcerides, phospholipids)
• protein metabolism (ammonia -> urea)
• hormone metabolism
• activation of Vitamin D
• vitamin, metal and carbohydrate storage
• synthesis of coagulation factors
• synthesis of plasma protein
• detoxification (endo- and exo-genous substances)
• immunity (Kupffer cells)
• secretion of bile

Question 2

What hormones are degraded in the liver?

Answer 2

insulin
steroid hormones
glucagon
ADH

Question 3

What does the liver store?

Answer 3

vitamins (A, B12, E D K)
Cu, Fe
Glycogen

Question 4

What are Kupffer cells?

Answer 4

Liver phagocytes that destroy cell debris (RBCs) and bacteria

Question 5

What stimulates opening of the sphincter of Oddi, leading to the release of bile into the duodenum?

Answer 5

• vagal stimulation

- CCK

Question 6

What are the components of bile?

Answer 6

bile acids (form bile salts)
electrolytes
lipids and phospholipids
cholesterol
IgA
bilirubin
drugs and toxins

Question 7

What is Cholelithiasis?

Answer 7

Gall stones in the common bile duct

• most common disease of the biliary tract
• treated with laparoscopic cholecystectomy

Question 8

What analgesia is appropriate for cholelithiasis?

Answer 8

• morphine is NOT suitable - it constricts the sphincter of Odi, increasing intrabiliary pressure
• buprenorphine (opioid) can be used

Question 9

What are the consequences of enterohepatic recycling?

Answer 9

• the patient needs a smaller drug dose

- a small fraction only is lost in faeces, the rest is reabsorbed

Question 10

What are the effects of bile-binding resins (drugs)?

Answer 10

Reduction of cholesterol levels

• more bile is excreted in faeces
• hepatocytes respond by converting more cholesterol into bile acids
• LDL clearance is thus promoted

Prescribe for: cholestatic jaundice, hyperlipidaemia

Question 11

What are the phases of drug metabolism by the liver?

Answer 11

Phase I (oxidation, reduction, hydrolysis) - enables addition of a reactive side group (conjugation).
Phase II (conjugation) - increases polarity of the drug.

Question 12

What reactions are mediated by the Cytochrome P450 (CYP) enzymes?

Answer 12

oxidation reactions - Phase I

Question 13

What is Hepatic Encephalopathy?

Answer 13

-Liver failure results in failure to detoxify NH3 to Urea, resulting in high NH3 blood levels which cause systemic effects, such as comma.

Treatment:

• Lactulose (osmotic laxative) reduces colon pH, which converts NH3 to ammonium (NH4), which is not absorbed.
• Inhibit NH3 geberation with antbiotics

Question 14

BNF link

Answer 14

https://www.evidence.nhs.uk/formulary/bnf/current