statins

Question 1

what are statins also known as?

Answer 1

HMG-CoA reductase inhibitors

Question 2

which statin is the most lipophilic?

Answer 2

atorvastatin

Question 3

what are the indications for statins?

Answer 3

1. hypercholesterolaemia
   - first line treatment for this with hyperlipidaemia
2. primary prevention of cardiovascular disease
   - prevent cardiovascular events in patients aged 40+ with a 10yr cardiovascular risk of 20%
3. secondary prevention of cardiovascular disease
   - first line drug, alongside lifestyle changes

Question 4

what is the mechanism of action of statins

Answer 4

they competitively inhibit the enzyme HMG-COA reductase.

this enzyme catalyses the reduction of HMG-COA to mevelonate. this is the rate limiting step in hepatic cholesterol biosynthesis.

inhibition of HMG-COA reductases decreases cholesterol synthesis.

Question 5

what does inhibiting HMG-COA reductase lead to?

Answer 5

it leads to a decrease in cholesterol synthesis. it also leads to

• up regulation of LDL receptors in the liver. increasing LDL uptake by the hepatocytes and decreasing LDL cholesterol in the bloodstream
• reduce triglycerides and increases HDL cholesterol levels

Question 6

what are the common side effects of statins?

Answer 6

many patients have no side effects.

• headaches
• muscle aches
• diarrhoea
• gi disturbance
• asthenia
• nausea

Question 7

what are some rare side effects?

Answer 7

• statins may cause myopathy alongside myalgia that can progress into rhabdomyolysis.
• hepatotoxicity
  may become toxic to the liver

Question 8

what is rhabdomyolysis and how do we test for it?

Answer 8

the muscle breakdown due to statins. so severe the muscle releases myoglobin. this causes patients urine to be coca-cola brown colour.

to test a CPK lab test will be done to measure the amount of cpk the muscles have released.

if rhabdomyolysis is indicated statin should be stopped STAT.

Question 9

how do we test for hepatotoxicity?

Answer 9

an LFT test is done. if the LFTs are 3x greater than normal then the statin should be stopped.

Question 10

what are the contraindications of statins?

Answer 10

• should not be used in pregnant women or breastfeeding women as cholesterol is needed for normal healthy foetal development
• caution in patients with hepatic impairment

Question 11

what are the interactions of statins?

Answer 11

• metabolism of statins is reduced by cytochrome p450 inhibitors
  
  • amiodarone (increases risk of rhabdomyolysis)
  • macrolides
  • protease inhibitors