Step 1: Understanding the Question:
The question asks which type of drug delivery system Nitrodisc is an example of.
Step 2: Key Formula or Approach:
A drug delivery system is classified by the route through which the drug enters the body. A transdermal system delivers a drug through the skin into the systemic circulation, using the skin as the entry point rather than the gut, the eye, the nose, or a mucosal surface.
Step 3: Detailed Explanation:
Nitrodisc is a patch containing nitroglycerin, a drug used to relieve and prevent angina by dilating blood vessels. The patch is stuck onto the skin, and the drug slowly diffuses across the skin layers into the blood vessels underneath, giving continuous systemic drug levels over about a day without needing repeated dosing. Because it avoids the digestive tract, it also skips first-pass metabolism in the liver, which would otherwise break down a large fraction of an oral dose of nitroglycerin before it reached circulation. This skin-to-bloodstream route is the defining feature of a transdermal drug delivery system.
Step 4: Final Answer:
Nitrodisc is an example of a transdermal drug delivery system.