Pharmacology Flashcards
What are lipids used for in the body?
Membrane biogenesis Membrane integrity Energy source Precursors for hormones Signalling
How are non-polar lipids transported in the blood?
Within lipoproteins (e.g. HDL & LDL)
What is the basic structure of a lipoprotein?
Hydrophobic core (contains triglycerides) Hydrophilic coat (contains cholesterol, phospholipids, apoproteins)
What are the 4 main lipoproteins?
HDL
LDL
VLDL
Chylomicrons
What apoproteins do HDL particles contain?
apoA1 & apoA2
What apoproteins do LDL particles contain
apoB-100
What apoproteins do VLDL particles contain?
apoB-100
What apoproteins do chylomicrons contain?
apoB-48
What is the role of ApoB-containing lipoproteins?
Deliver triglycerides to:
(i) muscle for ATP biogenesis
(ii) adipocytes for storage
Where are chylomicrons formed?
Intestinal cells
What do chylomicrons transport?
Dietary triglycerides
What pathway do chylomicrons use to transport triglycerides?
Exogenous pathway
Where area VLDL particles formed?
Liver cells
What do VLDL particles transport?
Triglycerides synthesised in that organ
What pathway do VLDL particles use to transport triglycerides?
Endogenous pathway
What are the steps in the ‘life cycle’ of an ApoB-containing liposome?
Assembly
Intraday ulnar metabolism
Receptor mediated clearance
What does Lipoprotein lipase (LPL) do?
Hydrolyses core triglycerides to free fatty acids and glycerol which enter tissues
Where does clearance of apoB-containing lipoproteins occur?
The liver
What is HMG Co-A reductase?
Rate limiting enzyme in de novo cholesterol synthesis
Which organ has the capacity to eliminate cholesterol from the body?
The liver (Secreted into bike or used to synthesise bile salts)
What is the difference between primary and secondary dislipidaemia?
Primary - caused by diet & genetic factors
Secondary - consequence of other disease
What is the mechanism of action of statins?
Competitive inhibitor of HMG-CoA reductase
Rate limiting step in cholestrol synthesis in hepatocytes
How does inhibiting HMG-CoA reductase lower cholestrol?
Decreased cholestrol synthesis
Increase in LDL receptor expression
Benefits of statins?
Lower cholesterol Decrease inflammation Reverse endothelial dysfunction Decreased thrombosis Stabilisation of atherosclerotic plaques
How are statins administered and at what time of day?
Orally at night
Adverse effects of statins?
Myositis Rhabdomyolosis (more likely if combined with a fibrate)
In what patients are fibrates first line treatment?
Patients with very high triglyceride levels
What is the mechanism of action of fibrates?
Agonists of PPAR alpha to enhance transcription of LPL encoding gene
Adverse effects of fibrates
Myositis
Rhabdomyolosis
(Best avoided in alcoholics)
Incidence for other adverse effects is greater than for statins
Example of bile acid binding resins?
Colestyramine
Cholestrol
Closevelam
What is the mechanism of action of bike acid binding resins?
Cause the excretion of bile salts resulting in more cholestrol being converted to bile salts
Adverse effect of bile resins?
G.I. tract irritation
What does ezetimibe do?
Reduces cholestrol absorption by inhibiting NPC1L1
Adverse effects of ezetimibe
Diarrhoea
Abdominal pain
Headache
In what patients is ezetimibe contraindicated?
Breast feeding females