a nurse is caring for a client who is receiving nitroglycerin iv and is switching to the oral form of the…

a nurse is caring for a client who is receiving nitroglycerin iv and is switching to the oral form of the medication. the nurse should identify that the oral dose will be higher than the iv dose for which of the following reasons? the iv form crosses the blood - brain barrier. the oral form has a decreased half - life. the oral form has decreased bioavailability because of the first - pass effect. the oral form has an increased rate of excretion.

a nurse is caring for a client who is receiving nitroglycerin iv and is switching to the oral form of the medication. the nurse should identify that the oral dose will be higher than the iv dose for which of the following reasons? the iv form crosses the blood - brain barrier. the oral form has a decreased half - life. the oral form has decreased bioavailability because of the first - pass effect. the oral form has an increased rate of excretion.

Answer

Answer:

The oral form has decreased bioavailability because of the first - pass effect.

Brief Explanations:

The first - pass effect (also known as first - pass metabolism) occurs when a drug is absorbed from the gastrointestinal tract and transported to the liver via the portal vein. In the liver, the drug may be metabolized (broken down) to a significant extent. Intravenous (IV) administration bypasses the gastrointestinal tract and the first - pass metabolism in the liver. So, for a drug like nitroglycerin, when switching from IV (which has 100% bioavailability as it bypasses first - pass metabolism) to oral (which undergoes first - pass metabolism and thus has lower bioavailability), a higher oral dose is needed to achieve the same therapeutic effect as the IV dose.

  • The IV form crossing the blood - brain barrier is not relevant to the dose difference between IV and oral forms.
  • The half - life of nitroglycerin (oral form has a short half - life, but this is not the reason for the higher oral dose compared to IV. The key is bioavailability).
  • The rate of excretion is not the main factor here; the first - pass effect on bioavailability is the critical reason for the higher oral dose.