Which routes have rapid absorption?

Which routes have rapid absorption?

• A. Intravenous (IV) and sublingual
• B. Oral
• C. Transdermal
• D. Rectal

Answer: (A)

Absorption rate is fastest when the drug reaches the bloodstream quickly without barriers. Intravenous administration delivers the drug directly into the circulation, so onset is immediate and bioavailability is essentially 100%. Sublingual administration also produces rapid absorption because the under-tongue mucosa is highly vascularized, allowing quick entry into the bloodstream and avoiding first-pass metabolism by the liver. In contrast, oral dosing must travel through the GI tract and undergo first-pass metabolism, leading to slower and more variable onset. Transdermal delivery passes through the skin and is designed for gradual, sustained absorption, not rapid onset. Rectal administration can be variable and is generally slower than IV or sublingual, depending on formulation and blood flow. So, the routes with rapid absorption are intravenous and sublingual.

Absorption rate is fastest when the drug reaches the bloodstream quickly without barriers. Intravenous administration delivers the drug directly into the circulation, so onset is immediate and bioavailability is essentially 100%. Sublingual administration also produces rapid absorption because the under-tongue mucosa is highly vascularized, allowing quick entry into the bloodstream and avoiding first-pass metabolism by the liver.

In contrast, oral dosing must travel through the GI tract and undergo first-pass metabolism, leading to slower and more variable onset. Transdermal delivery passes through the skin and is designed for gradual, sustained absorption, not rapid onset. Rectal administration can be variable and is generally slower than IV or sublingual, depending on formulation and blood flow.

So, the routes with rapid absorption are intravenous and sublingual.