Question

When a patient asks the nurse why a lower dose of intravenous pain medication is being given than the previous oral dose, what knowledge will the nurse draw on for her response?

a)The differences in absorption rates between oral and intravenous routes
b) Intravenous medications bypass the liver, causing increased potency
c) Medications given intravenously are not affected by the first-pass effect
d) Intravenous administration leads to a slower onset of action compared to oral medications

Answer 1

Intravenous pain medications require lower doses than oral ones due to immediate systemic distribution and the absence of the first-pass effect, which reduces drug potency when taken orally.

Step-by-step explanation:

When a lower dose of intravenous pain medication is being given than the previous oral dose, it's important to know that medications given intravenously have immediate systemic distribution without being affected by the first-pass effect. This effect refers to the initial metabolism in the liver of a drug absorbed by the oral route, which can significantly reduce the amount of an active drug reaching the systemic circulation. Moreover, intravenous medications bypass the liver, leading to increased potency compared to orally administered drugs, which must be absorbed in the GI tract first. The intravenous route ensures that drug levels in plasma are quickly attained at therapeutic concentrations, thereby requiring lower doses to achieve the desired effect compared to oral administration.