Why are adrenergic agonists such as epinephrine given parenterally or by inhalation instead of orally?

Question

Quizplus · Accepted Answer

Rationale 1: Adrenergic agonists are not digested in the gastrointestinal tract.
Rationale 2: No toxic by-products are produced.
Rationale 3: Adrenergic agonists are not rapidly absorbed by the blood.
Rationale 4: Epinephrine is metabolized by the enzymes MAO and COMT in the liver and in most tissues; hence, it is not taken orally.

Why Are Adrenergic Agonists Such as Epinephrine Given Parenterally or by Inhalation