Lipid-soluble drugs that enter the lymphatics may bypass first-pass metabolism, affecting bioavailability how?

• A. They are completely destroyed by liver and have low bioavailability.
• B. They bypass first-pass metabolism and can have higher bioavailability.
• C. No absorption occurs.
• D. They always require parenteral administration.

Answer: (B)

Lipid-soluble drugs that enter the intestinal lymphatics can bypass hepatic first-pass metabolism, which can raise their bioavailability. When these drugs dissolve in dietary fats, they’re packaged into chylomicrons in enterocytes and then ride the lymphatic system rather than the portal vein. This means they reach systemic circulation with less hepatic (and intestinal wall) metabolism before entering the bloodstream, leading to higher overall exposure compared with drugs that go through the portal route. The extent of this effect depends on factors like the drug’s lipophilicity, formulation (often lipid-based systems), and whether fat is present in the meal.

So the best statement is that they bypass first-pass metabolism and can have higher bioavailability. The other options don’t fit: there isn’t complete destruction by the liver after lymphatic uptake, absorption can and does occur via this route, and parenteral administration isn’t always required since oral lipid-based formulations can utilize lymphatic transport.