Pharmacology

Question 1

What is the mechanism of action of tranexamic acid?

Answer 1

Inhibition of plasmin and thus prevents fibrin degradation.

Tranexamic acid is a synthetic derivative of lysine. Its primary mode of action is as an anti fibrinolytic that competitively inhibits the conversion of plasminogen to plasmin. Plasmin degrades fibrin and therefore rendering plasmin inactive slows this process.

Question 2

What proportion of the sodium that is filtered at the glomerulus will be subsequently excreted in patient taking loop diuretics?

Answer 2

up to 25%

The loop diuretics can lead to marked increases in the amount of sodium excreted. They act in the medullary and cortical aspects of the thick ascending limb of the loop of Henle. This results in a decreased medullary osmolal gradient and increases free water excretion (as well as loss of sodium). Because loop diuretics result in the loss of both sodium and water they are less frequently associated with hyponatraemia than thiazide diuretics (these latter agents act in the cortex and do not affect urine concentrating ability).

Question 3

What clotting factor does Warfarin affect?

Answer 3

Factors II, VII, IX, and protein C.

Question 4

What is the most beneficial agent for pt that has bleeding due to underlying von willebrands disease?

Answer 4

Desmopressin.

asopressin is less likely to be disease specific and at most would have a vasoconstrictor approach which is likely to be of brief duration.

Question 5

What anaesthetic agent is most likely to induce adrenal suppression?

Answer 5

Etomidate

Question 6

Which of the local anaesthetics is not an amino amide type?

Answer 6

Procaine