Wed3November0919PM 2

Glyceryl trinitrate (GTN) is used for the acute treatment of angina and heart failure.

Which of the following is the reason why GTN is best administered via the sublingual route?

(Please select 1 option)

Significant presystemic metabolism by intestinal mucosa

Low volume of distribution

Causes gastric irritation

High first pass metabolism Correct

Poor gastric absorption

Explanation

Glyceryl trinitrate (GTN) is subject to significant first pass metabolism. Once absorbed by the intestine 90% of a dose of GTN is metabolised in the liver by glutathione organic nitrate reductase.

There is also an insignificant amount of metabolism in the intestinal mucosa.

Bioavailability is 38% after sublingual and 1% for oral administration.

GTN is well absorbed by the gastrointestinal tract and is not known to cause gastric irritation.

The volume of distribution GTN is relatively high at 2.1 to 4.5 L/kg.

Answer Statistics

1

14%

2

3%

3

1%

4

78%

5

5%

Times answered: 267