Question

A nurse is giving a medication that has a high first-pass effect. The physician has changed the route from IV to PO. The nurse expects the oral dose to be:

a) Higher because of the first-pass effect
b) Lower due to increased bioavailability
c) Unchanged as it bypasses the liver
d) Equivalent due to different metabolic pathways

Answer 1

The nurse would expect the oral dose to be higher because of the first-pass effect, as this process reduces the bioavailability of the drug when administered orally, resulting in the need for a higher dose to achieve the desired therapeutic effect.

Step-by-step explanation:

When a medication that has a high first-pass effect is changed from IV (intravenous) to PO (oral) administration, the nurse would expect the oral dose to be higher because of the first-pass effect. The first-pass effect refers to the process where a drug's concentration significantly decreases before it reaches systemic circulation, mainly due to the metabolism in the liver that occurs when a drug is administered orally. The bioavailability of a drug is the proportion of the drug that enters the systemic circulation when introduced into the body and so is able to have an active effect.

Since oral administration involves the drug passing through the digestive system before entering hepatic circulation, the first-pass effect can greatly reduce the amount of active drug that reaches the bloodstream. Therefore, oral doses usually need to be higher to account for this loss. In contrast, IV administration introduces the drug directly into the bloodstream, bypassing the liver initially, which results in a higher bioavailability and means a lower dose can be used to achieve the same therapeutic effect.