New Zealand Pharmacology for Midwifery Students Practice Test

The primary disadvantage of oral drug administration is first-pass metabolism. This phenomenon occurs when a drug is absorbed from the gastrointestinal tract and then transported to the liver through the portal vein before it reaches systemic circulation. In the liver, the drug can be metabolized and potentially rendered less effective or inactive before it enters the bloodstream, reducing its overall bioavailability.

In contrast, immediate effect, high bioavailability, and non-invasive methods are typically seen as advantages of oral administration. While some drugs may exhibit a rapid onset of action when taken orally, many are subjected to this first-pass effect, which can complicate dosing regimens and limit therapeutic effectiveness. Therefore, understanding the impact of first-pass metabolism is crucial for midwifery and pharmacology, particularly when considering how to optimize drug therapy for patients.